Penelopedia: Nature and Garden in Northfield, MN

May Birding Notes on Patch

noreply@blogger.com (Penelopedia) — 2012-05-27T14:05:00-07:00

Female ruby-throated hummingbird

My monthly Northfield Patch blog post, May Birding Notes, is now live. This month's edition discusses hummingbirds, orioles, bluebirds, sparrows, swallows, tanagers, warblers, hawks and vultures. May 6 was our first day this year to see both hummingbirds and orioles, and on May 12 I saw my first-ever orchard oriole in a large oak in the Carleton Arboretum.

Here's a preview:

Most of the spring bird migration has occurred, with a big last push expected this coming week. Our summer avian residents are now here. Here are some recent birding observations in and around Northfield:

Hummingbirds: We put out our hummingbird feeder at the beginning of the month, and I first noticed a hummingbird on May 6. Lately we have been seeing females numerous times a day, but sometimes also a male. The ruby-throated hummingbird is the only hummingbird to be expected in this part of the country. If you see one with a pale throat, it is the female. The irridescent red throat of the male can sometimes look purple or black, depending on the light.

Read the rest here.

The King of Orange - Baltimore Oriole at Feeder

noreply@blogger.com (Penelopedia) — 2012-05-22T16:26:00-07:00

I've had plenty of opportunity to observe our feeders the last few days while at home recuperating from minor surgery. I've been hoping to capture a male oriole at the oriole feeder in good light, and finally had the chance this evening. He and his mate have been regular visitors the last couple of weeks, but they don't stay long and are quick to depart if they sense motion nearby, so it's not easy to get a photo set up. This time he hung around for just long enough. By the time I pressed the shutter again, he was gone.

Baltimore oriole (male) at feeder

He gives a long percussive chittering call when he arrives at the feeder, which helps me look up at the right time to see him; I've noticed that blue jays also often announce their arrival. I suppose it is a territorial/possessive statement ("MY feeder. MY grape jelly."), but I appreciate that he announces his presence since I never tire of seeing this beautiful bird, which is just with us for a few months each year.

The songs and calls of the Baltimore oriole are quite varied. You can hear several versions at the All About Birds site. I don't hear the percussive call I've described in any of these samples; it may be the "sharp, repetitive chuck" that is described as an alarm call in the text. None of these samples offers the song that's on my Audubon bird clock, either -- the one that sounds like "Figaro Figaro Figaro."

We offer both grape jelly and orange halves at this feeder but, although orioles are said to like oranges, the oranges are ignored while the jelly is gobbled down.

More About Turkey Vultures

noreply@blogger.com (Penelopedia) — 2012-05-17T03:51:00-07:00

Earlier this spring we saw five turkey vultures atop an abandoned barn while checking our bluebird boxes near Northfield (see March 24 blog post). A few weeks later we saw two turkey vultures on the edge of the hayloft of the same barn and wondered if they might be nesting there (see April 27 blog post). Last weekend in the same area we saw nine turkey vultures soaring overhead, quite close to each other, and soon afterwards we passed the barn again and found seven turkey vultures resting on the roof.

I did some more reading about turkey vultures, and learned that they roost in large community groups but tend to forage independently during the day. So my early guess that a group seen together in early spring suggested the previous year's family unit is not necessarily right at all. But it's interesting to learn that they are communal birds.

The bird on the far right, above, is spreading its wings while resting. This is a common stance for the turkey vulture and is known as the "horaltic pose." The Turkey Vulture Society says:

The stance may serve multiple functions, including warming the body and drying the wings. Research on this pose suggests that turkey vultures spread their wings in the mornings, once the sun's intensity reaches a certain level, to raise their body temperature (which they lower at night by a few degrees as an energy saving mechanism). [see Turkey Vulture Facts page]

This photo was taken at about 4:20 p.m., for what that's worth.

If you see turkey vultures circling in an area, it does not necessarily mean there is a dead animal nearby. The same site says, "Circling vultures may be gaining altitude for long flights, searching for food, or playing."

I like the idea of such large birds playing.

Bluebird Trail, Week 7 - Mom on Nest, First Fledging & Tree Swallow Eggs

noreply@blogger.com (Penelopedia) — 2012-05-13T21:07:00-07:00

Mama bluebird on her nest

While we were checking Trail 2 today, a female stayed on her eggs when we opened one of the boxes. We have had a bird fly from a box as we've opened it before, but this was the first time one has stayed. It was quite a magical moment. We weren't able to ascertain how many eggs she's sitting on -- last week there were two eggs in this nest, so if she has the typical clutch of five, she's probably been incubating them for about four days and they'll hatch in another 8 to 10 days.

Trail 2 Box 4 nestlings at about 10-11 days

The nestlings are already quite advanced in the other Trail 2 box that has bluebirds in it (see photo above). We didn't know just when they hatched, but we estimate them to be at 10 or 11 days today, as shown in the photo above. This is the first photo we have that shows a nestling with an eye open. You can see they are becoming quite well covered with feathers.

Our very first nestlings, those in Box 9, have fledged. They were due to do so this past week, and on Saturday we found the box empty and the nest flattened out to accommodate the nestlings as they grew. You can see from the dark edges of the nest in the photo below that the nest was quite wet underneath. There was a lot of rain last week, and that box's opening faces south, exposing it to the prevailing direction of many of our rainstorms. Fortunately, as far as we can tell, the nestlings' health was not compromised. We cleaned out the box after taking this photo so that it is available for another nest. From what we've read, building the nest is an integral part of the reproductive urge, so it doesn't help to leave an old nest in place -- and starting fresh is more sanitary.

Flattened nest left after bluebird nestlings fledged

Nestlings are also very close to fledging in Box 16, if they have not already done so, and the Box 14 nestlings are due to fledge in the next few days.

Tree swallow nest with eggs in Box 15

We were very excited to find six eggs in our Box 15 tree swallow nest yesterday. We love seeing these feathery nests. We several times noticed tree swallows at Box 1 on our property today, as well -- one of the pair of boxes that have remained mainly empty but suffered the early chickadee loss to a house sparrow. And there is a bit of new moss in the other box, so we're hoping a chickadee is trying again. Still, we can sometimes hear a house sparrow nearby, so that threat remains.

Last week I did an abbreviated recap of our trail results. It's helpful to me to keep more detailed notes here, however, so those appear in the list below. Our Trail 1 totals so far: 25 nestlings! 5 fledged, 10 more are close to fledging, 5 more will probably fledge toward the end of this week, five more young nestlings, and only one nest still with bluebird eggs in it -- the worrying slow clutch of three pinkish eggs. This week they felt cold. The parents are always close by, but perhaps they just don't have the hang of this incubation business. We also have a nest of six tree swallow eggs. On Trail 2 we have four or five nestlings that should fledge in the week ahead, plus an unknown number of bluebird eggs being incubated in another nest, and one tree swallow egg so far in a third nest.

Trail 1:

Tree swallows observed on the box; box remains empty.
(Paired with #1) New moss this week, so we put the chickadee sleeve back on this box to reduce the entry hole size.
House wren had started to put sticks into nestbox -- removed.
(Paired with #3) This is now clearly a tree swallow nest with large feathers; no eggs yet.
Five nestlings, 11-12 days old.
(Paired with #5) Tree swallow nest. No eggs.
House wren nest with one egg.
(Paired with #7) Now empty; previously contained a few strands of grass for several weeks. Wrens can clear nests.
Our first clutch to fledge. Nestbox was empty; we cleaned it out.
(Paired with #9) Complete nest, no eggs - no change.
Discontinued
Discontinued
Five nestlings approx 5 days old.
Nestlings close to fledging; parents still vigilant on wire when a tree swallow approach the box, so we suspect fledging has not occurred yet.
Tree swallow nest with six eggs.
Nestlings may have fledged or will do so shortly - we did not open the box. We did not open this box last week either, as parents were very protective.
This box contained a substantial bed of moss for two weeks, but was suddenly empty last week -- a sign of possible house wren activity.
(Paired with #17) Three pale pink bluebird eggs, cool. These eggs are past the age when they should have hatched with consistent incubation. Parents are always nearby and vigilant (swooping down at us protectively), but we fear incubation has not been successful.
Tree swallow nest - no eggs.
(Paired with #19) Partial nest.

Trail 2:

Nest with several tiny dark downy feathers.
Bluebird stayed on nest so we could not count eggs. Last week there were two cold eggs, so assuming a total clutch of five, probably four days into incubation.
Tree swallow nest, one egg.
Five nestlings approx. day 10-11.

Splish Splash, Goldfinches Taking a Bath

noreply@blogger.com (Penelopedia) — 2012-05-07T19:28:00-07:00

Here is a little slideshow I made from a series of shots of a pair of American goldfinches having a really good splash in a puddle.

Bluebird Trail, Week 6 - 20 Nestlings!

noreply@blogger.com (Penelopedia) — 2012-05-06T21:27:00-07:00

This week sped by, and we did not visit any of the nestboxes after Monday. As a result, the photo I posted last Tuesday of the Box 9 nestlings on day 8 will be our last photo of them, unless we are lucky enough to get any photos after they fledge. Today (Sunday) they are at day 14 since hatching, and standard bluebird monitoring advice is not to open the box from about day 13 on unless there is a compelling need, because it is too close to their fledging date (most often 17-18 days, though it can take several days longer).

By day 13 or so they are fully feathered, and the fear is that they may be startled into fledging prematurely, which could endanger them. This risk is thought to be less with the top-opening Gilbertson boxes we are using than with front-opening or side-opening boxes, but we don't want to take any chances. But we will try to stop by later this week, and in the weeks ahead as we continue to monitor these boxes, to see if we can see any sign of them out and about with their parents. The male, in particular, will continue to tend to them for several weeks to come; mama, in the meantime, may start building her next nest almost immediately.

Box 5 nestlings at Day 4

Our fourth clutch of eggs, at Box 5, hatched probably Tuesday or Wednesday last week, and so were about at day four when we stopped by on Saturday (above). You can see some feathers lining this bluebird nest.

Tree swallow nest - note prominent, curling feathers. No eggs yet.

We were able to get a photo of the tree swallow nest in Box 15 (above) on Saturday. Bluebirds and tree swallows both make their nests of dried grass, but tree swallows make much more liberal use of feathers in the nest, and the feathers tend to curl up to surround the eggs (though there are no eggs yet in either the box above or the one below), rather than merely lining the nest. We have seen small feathers in several of our bluebird nests, such as the one with the nestlings above, but in comparison tree swallow nests are very feathery indeed.

Tree swallow nest on Trail 2 - no eggs yet

Above is another tree swallow nest. It is from the other set of boxes we are temporarily (?) looking after. We'll call those boxes Trail 2. Currently there are four nestboxes on Trail 2 -- two are paired, and the one above is one of those. There are two new bluebird eggs in the other box of this pair, and we have five new bluebird nestlings in one of the other boxes as of Sunday. We're waiting to see what develops in the fourth box, which contains a grass nest that looks as if it could be either a bluebird or a tree swallow nest at this point.

I am somewhat concerned about tree swallows using these Gilbertson nestboxes we are monitoring, ever since reading the opinion of the author of treeswallowprojects.com that these boxes, which have just a four-inch diameter, are dangerously small for tree swallow use, since tree swallows have larger clutches than bluebirds. People who put up nestboxes specifically for tree swallows are urged on that website never to use a box with a floor area smaller than 5 x 5 inches. I suppose cavity-nesters take what they can find to some extent, both in the course of their long natural history as well as in this age of humans providing nestboxes. One would think that a bird would "know" if a nesting cavity is too cramped for success, and would avoid it, but the treeswallowprojects site says that is, sadly, not the case. I will be interested to find out from Minnesota bluebirders who like the Gilbertson boxes what their experience has been with raising healthy tree swallows in them.

Below is one of the Trail 2 tree swallows, who sat very quietly nearby while we checked the box nearby and returned to this post when we walked past again after checking the other boxes. Tree swallows (and bluebirds too -- see below) are quite capable of diving at you from the air if they think you're too close to their nest, so we were quite surprised that this one did not display any aggressive protective behavior, though it was certainly watchful.

Tree swallow on fence wire

I took this next photo last weekend. I like the near-dusk softness of the landscape surrounding this handsome male bluebird.

Male bluebird at dusk

Box totals from our regular trail: 20 nestlings! There are five nestlings each in Box 9 (about 14 days old), Box 16 (about 12 days old), Box 14 (about 10 days old), and Box 5 (about 5 days old). As far as we know, they are all healthy. We did not look inside Box 16 this weekend, because the parents did dive at us when we approached the box, so we probably will not see those nestlings again for the same reason discussed at the start of this post -- they will very soon be too close to fledging.

There are still three pink eggs in Box 18, which is the same number as there were a week ago. They felt cool to the touch yesterday. The parents are always nearby and very vigilant, but we're not sure the incubation is proceeding as it should, so that is worrying. Stay tuned...

Not-So-Solitary Sandpipers in Flooded Field

noreply@blogger.com (Penelopedia) — 2012-05-06T06:44:00-07:00

Saturday evening, while doing our bluebird nestbox rounds south of Northfield, we noticed that the afternoon's heavy rains had left standing water in many farm fields. Flooded fields are prime habitat for migrating shorebirds, so we were on the lookout. At one particularly wet spot I saw something small and pale, so we pulled over to take a closer look.

We saw one, and then another, and eventually as many as seven or eight medium-sized shorebirds -- not all together, but here and there in ones and occasionally twos. A red-winged blackbird flew at one and flushed it, and we noted that the two birds were of very similar body size, which gave us a useful reference point. When we got close enough to see it, a noticeable white eye-ring confirmed the identification: these were solitary sandpipers. I just checked the comparative body length of the two species, and our impression of similar size was correct: solitary sandpipers are about 8.5 inches and red-winged blackbirds are about 8.7 inches.

We have most often seen these one at a time, as their name suggests, but the Cornell Lab's All About Birds site says, "While not truly solitary, it does not migrate in large flocks the way other shorebirds do," and National Geographic Complete Birds of North America notes that they are "usually seen singly or in small groups." Wet, grassy areas are a common setting for solitary sandpipers. On May 1 last year, in fact, we saw one in a flooded low area of lawn near our house, right in Northfield.

Like most of the shorebirds we see in Minnesota, these are just passing through on their way from their winter homes, ranging from southern Mexico into much of South America, to their breeding grounds in Canada and Alaska.

I was fascinated to learn just now, as I read about these pretty shorebirds, that they actually nest in trees, in the abandoned nests of songbirds, particularly particularly those of the American robin, rusty blackbird, eastern kingbird, gray jay, and cedar waxwing. The Cornell Lab site says, "Of the world's 85 sandpiper species, only the solitary sandpiper and the green sandpiper of Eurasia routinely lay eggs in tree nests instead of on the ground." This nesting habit was not discovered until 1903, 90 years after the species was first described by ornithologist Alexander Wilson.

So here are the things about solitary sandpipers that will stick in my mind:

White eye-ring
Same size as a red-winged blackbird (the legs and bills are very different, obviously)
Flooded fields are likely habitat (this is true for a number of shorebird species, of course)
They nest in trees!

Bluebird Nestlings at 8 Days

noreply@blogger.com (Penelopedia) — 2012-05-01T18:10:00-07:00

Here is the first group of nestlings again, eight days old as of Monday. Look how much more room they take up in the nest than they did a week ago. I was surprised how relatively unresponsive they were this time compared to earlier visits, displaying only one brief gape in the whole bunch. We thought perhaps their bellies were full and they were sleeping (and we did look closely to make sure they were actually moving) -- but then I read that right about this age, nestlings start to react differently. (Sialis.org) Instead of gaping when the box is opened, they hunker down with their eyes closed.

Eyes -- that's right, at this age their eyes may well have opened. We did not see any evidence that the eyes on this bunch had opened yet, but they may just have been keeping them closed. Their feathers are starting to come through; you can see them on the wings quite clearly.

Here's a nice page on Sialis.org that follows a brood day-by-day from hatching to fledging.

Bluebird Trail, Week 5 - Pink Eggs, Tree Swallows & More

noreply@blogger.com (Penelopedia) — 2012-04-29T20:05:00-07:00

We now have 15 nestlings and 13 more eggs among the 18 boxes we are monitoring at 11 sites. It's also clear that one of our bluebird nestboxes has become a tree swallow nest.

Papa bluebird has a caterpillar for the Box 9 babies

As I reported midweek, all five eggs did hatch at the first site, Box 9, and five more hatched a day or two later at Box 16. Now we also have five nestlings at Box 14 that hatched probably Thursday or Friday. It got pretty cold this week, but they all appear to be okay. I could hear tiny cheeping coming from the two boxes with the oldest nestlings, which was delightful. Once again, my camera's start-up chime got several nestlings to gape (below). That one at the top left doesn't look too vigorous, but it may just be the angle.

Box 16 - Nestlings Day 5 - note darkening where feathers will grow

Last week we started to suspect that Box 15 was being used by tree swallows, as we saw one making territorial swoops past the nestbox. This week it was confirmed, as I saw swallows landing on the house and, as you can see below, even emerging from it. I took the photo below from the car and then drove on to check another box rather than disturb them when they were so active at the box. When I came back they were not in sight, so I checked the box and found several prominent feathers in the nest, but no eggs yet. Bluebirds sometimes incorporate small feathers to line the grass nest, but tree swallows routinely use larger feathers and more of them.

Tree swallows at Box 15 (note one emerging)

During our mid-week check we found two eggs in one of our newest nests, Box 18, that at first led us to question whether this was indeed a bluebird nest. We had heard that a small percentage (perhaps no more than 7 percent) of bluebirds lay white eggs rather than blue. These eggs looked the right size and shape (tree swallow eggs are somewhat more pointed at one end), but they had a pinkish color, which was unexpected.

Though usually blue, bluebird eggs can be white, or even pinkish - Box 18

There was an agitated pair of adult bluebirds on a wire directly overhead, so we were fairly sure this was indeed a bluebird nest. We confirmed at the very helpful bluebird website Sialis.org that bluebird eggs can indeed be pink! I was there again today and found there are now three pink eggs, and mama bluebird (again on the wire) was most perturbed that I was looking into her nestbox, so I didn't linger to take another photo.

Here's the full report for the week. Boxes retain the same numbering all season, so even though two boxes have been taken over by another monitor we keep them in this list so the numbers will stay correct. We were invited to take on two more boxes this week, and were also asked to temporarily monitor some in another location, the latter of which I have not added here. Calculations of incubation time are based on Sunday's early-afternoon nest check.

We saw a pair of house sparrows at these two boxes earlier this week, and a partial nest was built. We set the sparrow trap but have not had luck -- but the sparrows seem to have been discouraged from this nest.
(Paired with #1) No activity.
Partial nest - no change.
(Paired with #3) Nest about complete, no eggs - little or no change. Tree swallow noted nearby.
Five warm eggs, estimated to be 11 days into incubation, with hatching anticipated in the next 1-3 days. Male noted flying from the area of the nest.
(Paired with #5) Partial nest - no change.
Partial nest - no change.
(Paired with #7) A few strands of grass - no change.
Five nestlings approx. 7 days old - starting to look much darker and less naked. Tiny cheeping sounds from closed box. Four had hatched on our visit a week ago, and the fifth had hatched by the time we visited again midweek -- probably only a short time after the others.
(Paired with #9) Complete nest, no eggs - no change.
Discontinued
Discontinued
Five warm eggs - a week ago there were three cool eggs. Incubation probably five days along, with hatching anticipated in 7-9 days. Bluebird flew from box.
Five nestlings approx. 2-3 days old (they had not hatched as of Wednesday when we stopped by).
Full nest, no eggs. We now think this is a tree swallow nest. Tree swallows were observed on top of and inside the nest box (see photo above), and the nest contains several prominent feathers, which is characteristic of tree swallow nests.
Five nestlings approx. 4-5 days old, cheeping; both adults vigilant and agitated nearby.
Chickadee nest contains substantial bed of moss, but no change for the past two weeks.
(Paired with #17) Three pale pink eggs, warm (?). There were two eggs on Wednesday, so since bluebirds lay one egg per day it may be presumed the clutch is complete. If incubation began Thursday, they are 3 days into 12-14-day incubation, with hatching anticipated in 9-11 days. One egg at least felt warm; I wasn't sure if they all did. Adult female watchful and agitated nearby.
New box this week: A few strands of grass.
New box this week (paired with #19) A few strands of grass.

Follow the full saga of our bluebird trail at my Bluebird Trail page.

Cardinal Likes Suet

noreply@blogger.com (Penelopedia) — 2012-04-27T18:57:00-07:00

Northern cardinals don't usually have much chance to eat suet at our feeders, since the suet feeders are usually oriented upright -- designed for birds that can cling to them, like chickadees, nuthatches and woodpeckers. Cardinals aren't clingers, and they prefer flat, stable feeders. But recently on a whim we oriented a cage-style suet feeder horizontally, and this male cardinal took advantage of the opportunity.

Luckily, I was sitting right by the window with my camera at hand when this bird flew in, and I was able to get some really good close-ups. Cardinals are quite skittish and are quick to fly off if they sense movement (such as someone reaching for a camera). As a result I don't have many good cardinal photos. But these photos are hardly cropped at all, and if you click on them (or right-click to open the image in a new tab) they are really big -- big enough to see that the cardinal's eye is brown and that it has some of the suet mixture it its beak.

We recently had the pleasure of seeing a cardinal courtship ritual: the male offering the female a sunflower seed from our hopper-style feeder that usually attracts them. However, "Mrs." was not on hand for the visit to the suet feeder.

Nesting Turkey Vultures?

noreply@blogger.com (Penelopedia) — 2012-04-27T03:30:00-07:00

While doing our bluebird nestbox checks last Sunday, we saw two turkey vultures wheeling in the sky. Then they flew toward an abandoned barn and landed on what I think would be called the entrance to the hayloft (forgive me, I don't come from a farm background).

I did some quick research at the Turkey Vulture Society website and learned that turkey vultures do, in fact, commonly nest in abandoned barns. This setting is apparently an adequate equivalent for their traditional habit of nesting in caves, hollow logs, burrows and the like.

Pair of turkey vultures looking into barn

The thing is, we saw a group of five turkey vultures on the roof of this barn four weeks ago, our first "TV" sighting of the year. It was a very unusual sight to see a group like this.

Four of the five turkey vultures seen on same barn roof in March

So now I'm thinking that what we saw in March was quite possibly last year's family group, freshly returned from their wintering grounds, and maybe mom and pop are planning on raising a new brood in the same spot this year. The Cornell Lab of Ornithology says they may reuse a nesting site for many years.

The Turkey Vulture Society says TVs raise one brood a year, with one to three eggs but most commonly two. So a family group of five is certainly possible. They don't really build nests -- they just scratch out an indentation somewhere or arrange some vegetation. They incubate their eggs for close to 40 days, and fledging takes place 70-80 days after that. First-year vultures have gray, rather than red, heads. Now I wish the earlier photo was clearer so I could see if some of the heads weren't fully red yet.

Everything I've now read suggests it is very likely that this barn is a nesting spot for turkey vultures, and it's in a location we'll pass weekly as we do our bluebird rounds. I'm looking forward to what we might see of turkey vulture family life -- from a respectful distance -- in the weeks ahead.

I've just learned of a live turkey vulture cam installed in a barn in Missouri where vultures are apparently nesting. Read the article here, which contains a link to the live stream.

First Nestlings at Day 3

noreply@blogger.com (Penelopedia) — 2012-04-25T20:37:00-07:00

Here is the same group of nestlings as before, now three days after hatching. As you can see, the fifth egg did hatch. A moment before this photo was taken, they were all flopped down, but my camera made a little chime as it turned on, and the sound triggered their gaping reflex. They went from flopped to this position in the blink of an eye.

Box 9 nestlings at day three

We also found today that our expected second hatch at Box 16 had indeed occurred, with five more nestlings just a day or two behind Box 9. We were lucky enough to catch the first batch with one egg still unhatched, so we had a very close idea of when those hatched. This second box probably hatched either Monday or Tuesday, but we can't be sure exactly when.

Box 16 nestlings at day two (?)

And in case all these little squirming shrimpy things with gaping yolk-yellow mouths make you a little squeamish (I confess they have that effect on me if I look at these pictures too long), let's close with a reminder of what they will become, with a little luck and a lot of care and feeding from their doting parents, in an amazingly short period of time. This was a pair of birds on the wire above one of the other boxes we checked today.

Female (top) and male bluebirds

Bluebird Trail, Week Four: First Hatch

noreply@blogger.com (Penelopedia) — 2012-04-22T18:08:00-07:00

We visited our bluebird boxes this afternoon, fairly certain that we would have our first hatchlings -- and indeed we did. In the nest with the earliest eggs, four of the five had hatched. The wonderful bluebird website Scialis.org says newly hatched bluebirds look like hairy shrimp, and that is right on the money. Look at their tiny wings, their sealed-over eyes and that gaping mouth. Baby birds sure are designed to show mom and dad where to deposit the food!

Four of five bluebirds hatched

Notice that the shells of the hatched eggs are already gone. In many cases the mother eats them, recapturing the calcium in them, or she may remove them from the nest. It's possible that the fifth egg will not hatch. In most cases all successful eggs will hatch within around 24 hours of each other. We'll check again in a day or so.

First-day (sometimes called Day 0) bluebird hatchlings

It was a cool week, with both frost and a lot of rain. Cool weather can slow down incubation, and cold and wet conditions can endanger nestlings as mama comes back to the box with wet feathers. All the boxes appeared dry inside. Our BBRP county coordinator, Keith Radel, made sure all the ventilation holes in the PVC boxes were taped over securely with black electrical tape when we made our introductory rounds. This is a good practice at least for the cool springtime nesting. Bluebirds will typically have a second clutch and sometimes even a third in a season; since this year's nesting got an early start, this may well be a three-clutch season for some. The ventilation holes can be opened up for heat relief later in the season, though some bluebirders feel this is not necessary and that it is more important to minimize the chance of wet nests.

Here's the full report for the week. Boxes retain the same numbering all season, so even though two boxes have been taken over by another monitor we keep them in this list so the numbers will stay correct. Calculations of incubation time are based on Sunday's early-afternoon nest check.

Empty except for a little moss we put into the box to encourage a chickadee.
(Paired with #1) Empty
Partial nest - little or no change
(Paired with #3) Nest about complete - little or no change
Last week there were three cool eggs in this nest; this week there were five warm eggs, so incubation is anywhere from one to four days along, with hatching due in 1.5 to two weeks.
(Paired with #5) Partial nest (no change)
Partial nest (more developed than last week)
(Paired with #7) A few strands of grass (no change)
Four nestlings that look newly hatched (see photos above), and one unhatched egg. Our first hatch! We had calculated hatching to occur between Friday and Sunday.
(Paired with #9) Complete nest, no eggs (no change)
Discontinued
Discontinued
Nest with three eggs, new this week. Eggs were cool - incubation has not begun.
Five warm eggs; female flew from box as we approached. These eggs were a day or two into incubation last week, so they are now eight or nine days into their 12-to-14-day incubation period. .
Nest looks complete (increase from last week), and looks like our other bluebird nests, but a tree swallow swooped close by several times while we were near the nest box.
Five warm eggs; female flew from the box when we opened it. Last week we calculated incubation to be about five days under way, so now it should be 12 days into incubation; hatching is imminent.
Last week this box had a substantial nest of moss, and we assume it is a chickadee nest. There is a chickadee sleeve on this box to reduce the hole size for this smaller bird. No change this week.
Paired with #17) A complete bluebird nest, in a box that was completely empty last week.

Total: Four bluebird nestlings and 19 bluebird eggs in five nests.

Follow the progress of our bluebird trail at my Bluebird Trail page.

Yellowlegs

noreply@blogger.com (Penelopedia) — 2012-04-18T18:25:00-07:00

Greater (or Lesser?) Yellowlegs at Lake Byllesby

This is not a bird whose name's origin you have to guess at. Those are extremely yellow legs.

I'm not positive whether this is a greater or a lesser yellowlegs. Does the bill look to you as if it is longer than the width of the head, and slightly upturned? It does to me, which would make it a greater yellowlegs. But the differences are subtle and the distinction can be difficult to make.

I was at Lake Byllesby with binoculars and spotting scope again last evening, hoping I might catch one of the shorebird rarities that have been popping up in migration. I had planned to be elsewhere, but I'd been indoors all day, and when it came down to it, I needed fresh air and quiet water and solitude.

I saw at least 80 pelicans on their favorite sandbar far out into the lake; I saw perhaps 40 or 50 each of green-winged teal and blue-winged teal, and some sprinklings of northern shovelers, coots and mallards. I saw several groups of shorebirds -- I think some lesser and some greater yellowlegs (I think I heard both calls), plus a small group of pectoral sandpipers. I saw two bald eagles overhead and the resident great horned owl on her nest.

No rarities this time, but spending the last hour of light on the edge of the lake -- the cool air echoing and rippling with the piercing calls of yellowlegs, the honking of geese and even the peculiar bark of a pelican -- was pleasure enough.

Bluebird Expo & Bluebird Trail, Week Three

noreply@blogger.com (Penelopedia) — 2012-04-16T17:21:00-07:00

This was a fun week -- no tragedies, quite a few eggs, and on Saturday, April 14, Dave and I attended the annual Bluebird Expo, our first, which was held in Byron, near Rochester, Minnesota.

Speaker in front of screen showing chicks in nestbox

At the Expo, we heard lots of good advice for successfully fledging bluebirds from people who have impressive records of doing just that. We also saw some wonderful video footage of wood ducks inside their nest boxes, learned about best practices in purple martin housekeeping, saw a wonderful presentation from the Raptor Center (a red-tailed hawk, a great horned owl, a peregrine falcon and a bald eagle), and laughed at stories from writer/humorist/birder Al Batt, known to many as Al B of Hartland in the Pioneer Press's Bulletin Board feature. You know all that honking Canada geese do when they're flying? It's the females asking the male in the lead why he doesn't just stop and ask for directions. Thanks for the laughs, Al.

Display of recommended bluebird nestbox styles

We bought some bluebird monitoring equipment (a nestbox cleaning tool, a sparrow trap), plus a Bluebird Recovery Program cap so we'll look official when we go around checking nestboxes. I got to see my blog friend Ruth, of Nature Knitter, and I was pleased that fellow Northfield newbie bluebirders Robbie and Griff Wigley also attended. Another friend we encountered there was Dan Kahl, the naturalist at Mount Olivet Retreat Center, who has been my Christmas Bird Count partner in Northfield the past two years. We were impressed by the planning and dedication that clearly goes into these bluebird conferences. Thanks to all involved. The Rochester Post-Bulletin covered the event in a story headlined State's bluebird population headed toward new high.

Three eggs in this nest Sunday, but cool, so not incubating yet

Now for the trail report: We had eggs in two additional nests this week, for a total of 18 eggs in four nests. In one location the mama was in the nestbox when we took it down to check it, though we had gently announced our presence with our voices and tapped on the outside of the box. She flew out in a hurry when Dave looked into the box! He thinks she was the more surprised of the two of them. She watched us from an overhead wire while we quickly assessed the eggs and attended to our other task of the week (more on that below). Perhaps next time she'll recognize the sounds of our approach and leave sooner, though we hear that sometimes a female will remain on the eggs during the nest check.

Five warm eggs - incubating

The task we did for each of our sites yesterday was to polish the metal conduit mounting pole with fine steel wool and then apply car wax to it, to make sure the pole was good and slippery to deter climbing by a cat, raccoon or other predator. If there were eggs in a nest, I carefully held the nestbox and covered the opening as best I could to minimize heat loss while Dave polished the pole, so the eggs wouldn't be jostled.

Chickadee nest - made of moss, not dried grass

In one of our two newest nestboxes, we had some moss last week. County coordinator Keith Radel helped us out by putting a chickadee sleeve on this nestbox, which reduces the size of the opening so larger birds like house sparrows can't get in and cause damage. This Sunday there was enough moss to make quite a cozy looking bed on which to lay tiny little chickadee eggs. We will eagerly await that occurrence!

Here's the full report for the week. Boxes retain the same numbering all season, so even though two boxes have been taken over by another monitor we keep them in this list so the numbers will stay correct. Calculations of incubation time are based on Sunday's nest check.

Empty
(Paired with #1) This is the nest box where the house sparrow killed the chickadee. Box continues empty but we have removed the sparrow trap because there is now a chickadee sleeve on the nestbox, in case another chickadee wants to use this location.
Partial nest (a bit further along than last week)
(Paired with #3) Nest about complete, with some feather lining (more developed than last week)
Last week I reported a complete bluebird nest with feathers lining the grass nest. This week we found three eggs (see top nest photo above), but they were cool to the touch, so incubation has not begun.
(Paired with #5) Partial nest (no change)
Partial nest (no change)
(Paired with #7) A few strands of grass (no change)
Bluebird nest that had five eggs last weekend had five warm eggs, so incubation should be about halfway complete.
(Paired with #9) Complete nest, no eggs (no change)
Discontinued
Discontinued
Complete nest (more developed than last week)
Bluebird nest with five warm eggs. Female was on eggs when box was opened and then flew to nearby overhead wire. There were no eggs in this nest last Sunday, so since bluebirds lay one egg a day the incubation started at most a day or two before our nest check.
Bluebird nest 75% complete (no change)
Five warm eggs in nest; a week ago this nest had three eggs, so incubation is probably five days under way.
Last week this box had a small amount of moss; this week there was a substantial nest of moss. Chickadee nest; chickadee sleeve applied.
(New box this week, paired with #17) - Empty

White-faced Ibis at Lake Byllesby

noreply@blogger.com (Penelopedia) — 2012-04-15T15:45:00-07:00

After a full day yesterday at the Bluebird Expo in Byron, Minnesota, we got home and read a report that Hudsonian godwits had been seen at Lake Byllesby yesterday. This would be a rare and brief stop-off on their long migration -- these large shorebirds winter in southern South America and breed in northern Canada and Alaska. When we went to the lake today, none were in evidence anymore (last night's strong south winds may well have given them a favorable tail wind out of the area), but experienced birders leaving the area as we were arriving reported seeing seven white-faced ibis (or ibises -- Merriam Webster says the plural can take either form). And sure enough, there they were in the shallows at the far west end of the lake, amid a good number of greater and lesser yellowlegs, pectoral sandpipers, ducks and more.

White-faced Ibis

This tall, dark, handsome wading bird gets the "white-faced" part of its name from the white outline around the face that is somewhat visible on the bird on the right in the photos above. It is rarely reported in eastern Minnesota. In the United States, it is found year-round along the Gulf Coast and in Southern California, particularly the Salton Sea, with summer breeding populations found mainly in the northwest and central U.S., usually no closer to us than eastern South Dakota and Kansas. With those population patterns, even in migration you wouldn't expect to see many of these birds as far north and east as we are (though I understand that Atlantic coast sightings have started to occur). You can see a map of eBird sightings of the White-faced Ibis reported since 2008 here.

White-faced Ibis and a couple of Lesser Yellowlegs

Below is a very short video of the birds taken through the spotting scope. The photos above were taken in the same manner, but it is easier to crop the black vignette out of those than to crop a video. The sun was shining on my LCD and I really couldn't see what I was getting, so I didn't let it run more than a few seconds, but you get the idea of their motion as they probe for goodies in the very shallow water and wet mud.

Penelopedia on Patch: April Birding Notes

noreply@blogger.com (Penelopedia) — 2012-04-13T06:11:00-07:00

I've submitted a few blog posts to Northfield Patch in the past, but my plan is now to do a monthly birding update, including other nature notes as they occur to me. My April Birding Notes went up on Monday, and I've copied the contents below. After I wrote it, we saw significant numbers of small shorebirds, saw our first yellow-rumped warbler of the year and heard our first common yellowthroat -- all from the cemetery area at the northwest end of Lake Byllesby.
-------------------

April Birding Notes

Our unprecedentedly warm March has led into a closer-to-normal April so far, though it's still been warmer than typical for this early in spring. Here are some recent birding observations in and near Northfield:

Robins and red-winged blackbirds have been back among us for the past month already.
Grackles, those long-tailed irridescent blackbirds, have been very evident this week; I counted about 50 by my house yesterday, including several who were checking out our bird feeders. European starlings, with their speckled black plumage and short tails, are also commonly seen.
Eastern bluebirds, too, have been sighted in the area since early-to mid-March and are building nests and laying eggs. We are monitoring several bluebird houses for the first time this year and have several nests and at least one clutch of eggs so far (see photo). I'll be reporting weekly on our bluebird trail at penelopedia.com.
American goldfinches are undergoing their spring moult. Watch for the male to appear in his bright yellow breeding plumage soon, but you may see some patchy transitional birds in the meantime. Goldfinches stay here through the winter, often visiting bird feeders, but you may not realize you have been seeing them since they look so much duller in their winter plumage.
Waterfowl, including ducks, grebes, geese and swans, have been migrating through the area for the past month or more. With ice going out so early on the lakes, they have been able to push through ahead of their normal pace. Blue-winged teal, wood ducks and of course mallards will breed here, but most other ducks we see in early spring are heading further north and west to their preferred breeding grounds in the great plains of the U.S. and Canada, or even the Arctic regions. I saw a pair of pied-billed grebes and a hooded merganser at one of the ponds near the soccer fields on Saturday. We sometimes see a loon on that pond in spring, but I have not seen one yet this year, and no loons have been reported on the eBird site yet this year in Rice, Dakota or Goodhue counties. American white pelicans have been showing up on area lakes for the past week or two.
Shorebirds are beginning to arrive. We've been hearing and seeing killdeer on fields and by ponds in town for about three weeks now; they will be here all summer. We have seen just a small number of greater yellowlegs at Lake Byllesby's shallow west access so far. The BirdCast Migration Forecast predicts our first significant wave of shorebirds through the Upper Midwest this week. The greater and lesser yellowlegs may stay with us during the summer, but most shorebirds are just passing through on their way to migration grounds in the Arctic. Look for them at wet farm fields, mudflats, or shallow edges of ponds and lakes.
Warbler migration is probably still a few weeks ahead of us (these neotropical migrants winter in Central and South America, so they're not likely to start early despite our early spring; how would they know?), but a birding friend reported seeing her first yellow-rumped warbler of the season this week. The yellow-rumpeds winter in the southern U.S., so they are typically the first warblers we see in spring. With the trees leafing out so early, it's going to be hard to see the warblers when they do arrive in large numbers.

If you wake early, listen to the "dawn chorus" as nesting season gets under way and songbirds are busy proclaiming their chosen territories. The cardinals have quite a variety of songs ("what cheer! what cheer!"; "birdie birdie birdie"; or "cheer cheer cheer" are common versions). Robins ("cheerily, cheerily, cheer up, cheerily!") start earliest, and the black-capped chickadee's descending major-second interval, "fee bee, fee bee," can be heard much of the day (their other familiar call is "chicka dee dee dee"). The call of the other "fee bee," the eastern Phoebe, heard less often in town, is raspier, sounding more like "fee zwee."

When you can start to identify a few birds by their songs, it's no longer just a wash of pretty sound; it's more like listening to a conversation between familiar friends.

Pelicans

noreply@blogger.com (Penelopedia) — 2012-04-11T20:46:00-07:00

I took a lot of photos at Lake Byllesby on Saturday, where I finally saw a nice flock of about 90 small shorebirds, and a couple of juvie eagles doing interesting things with their wings out on the mud/sand, and I thought I saw a couple of Franklin's gulls but maybe they were Bonaparte's gulls. And then I idiotically erased almost the whole lot during the upload process. Dave and I went back Sunday morning and there were not as many shorebirds, though we did see some -- probably lesser yellowlegs and, according to another birder we saw who was able to get a better look than we did, some pectoral sandpipers. I'd seen one shorebird with a long, downcurved bill on Saturday, and the other birder we saw confirmed that there was a dunlin in the group.

Pelicans - click to see photo larger

Both days there was a line of pelicans on their favorite sandbar well out into the lake. I counted a good 60 on Saturday and about 50 on Sunday.

Speaking of pelicans, these were American white pelicans, the only kind usually seen in these parts, but the rare bird alert has been buzzing with confirmed sightings of a brown pelican in Red Wing and other spots in the region in the past several days. Brown pelicans don't come here! They live along the ocean shores -- east coast, west coast and Gulf of Mexico. They are the only dark pelicans, and much smaller than the white ones we see here. I have seen them flying along the beach in northern California. That is one mixed-up or extremely-blown-off-course pelican. I hope it does okay.

Bluebird Trail, Week Two (Part 2)

noreply@blogger.com (Penelopedia) — 2012-04-08T20:18:00-07:00

On Friday night I poured my heart out about our first encounter with an aggressive house sparrow at a nest box, and I shared our delight at discovering our first clutch of bluebird eggs at one of the boxes we monitor. Today I finished visiting the rest of the boxes we've taken on. Here's the update:

Nest at box 9 on Saturday

Empty
This is the nest box where the house sparrow killed the chickadee. We have been setting a trap for the house sparrow but have had no luck.
Partial nest
Nest about half built
Complete bluebird nest with feathers lining the grass nest -- looks ready for eggs
Partial nest
Partial nest
A few strands of grass
Bluebird nest with five eggs as of yesterday (see photo). She should be done or almost done now, and incubation will start. That takes close to two weeks before chicks hatch.
Bluebird nest, no eggs. We are relieved that this female apparently decided to lay all her eggs in #9 rather than splitting them between nests built in both #9 and 10.
We are no longer monitoring boxes #11 and 12 -- someone else nearby has asked to watch those -- but for consistency with the numbers in our record book we'll keep the numbering the same.
See #11
Partial nest
Last week we thought a tree swallow might be building the nest in this box but this week it appears to be a pretty complete bluebird nest and I spotted a bluebird on the wire nearby
Bluebird nest 75% complete
Bluebird nest with three eggs as of today A bluebird flew from the area of the box as I drove up.
Newly assigned nest box as of this week, replacing #11-12. On Thursday this box contained a small amount of short clippings, possible moss, indicating maybe a chickadee.

Bluebird Trail, Week Two (Part 1) - Delight and Sorrow

noreply@blogger.com (Penelopedia) — 2012-04-06T20:57:00-07:00

This was a week of delight and sorrow on our bluebird trail.

First two bluebird eggs on our trail!

This is actually just part one of our Week Two report; we haven't been back out to all the nest boxes on our trail since last weekend, so I will follow this post with another in a couple of days, when we have a full report. But there is much to tell of our experiences with two of our nest boxes this week.

First, the delight. We were advised to check more frequently on the two boxes where a pair of bluebirds had built two nests (see #9 and 10 from last week's report), so on Wednesday evening my son and I went out there and found two beautiful blue eggs in the nest that had been started and completed first. We went back on Thursday and found a third egg, and still no eggs in the second nest box, which was good. Because of what we learned earlier on Wednesday about house sparrows, as described below, on Thursday we put up a sparrow spooker -- a short pole or more elaborate contraption with streamers fluttering from it and dangling on the roof of the box -- on top of the occupied nest box. There's evidence that house sparrows don't like those and will avoid them, but bluebirds don't seem to mind them much.

Same nest, next day - a third egg!

Now for the sorrow. This part is rather disturbing, and if you're squeamish you may want to stop reading now.

In the nest box where I'd noted last week that we thought we had a chickadee starting a nest (#2), we found our first evidence of what a house sparrow will do to other nesting birds. On Wednesday we saw a house sparrow on top of the nest box in the late afternoon and went to check it out. We discovered inside a poor chickadee that had been pecked to death, its head so badly injured it could hardly be seen (see photo below -- or if you don't want to see the photo below, you can click away to something else now). This is very typical of how house sparrows kill, I've learned, though it's less usual for them to go after an adult bird that does not yet have an active nest.

This very distressing discovery led to phone calls to our area bluebird coordinators, and Carroll Johnson came and brought us a Gilbertson trap, which blocks the exit hole of a nest box when a bird triggers it inside the box and keeps the bird inside until it can be released (which it must be, if a native bird) or euthanized (if a house sparrow). It's essential to get that house sparrow if we can and do away with it (humanely).

I am among the least violent of people. I would never kill an animal for sport (for food, if I had to, yes I suppose I would, but I would prefer to become even closer to being completely vegetarian than I already am if that choice presented itself). I don't even like to squish bugs, with the exception of mosquitoes or ticks that are going after me or mine. I rescue occasional small spiders from the bathtub before taking a shower so they won't drown. I did the same with a stray boxelder bug I found a few days ago. I would never have thought that I could do away with a bird -- until Wednesday. But I discovered through a little research that there's a saying among bluebirders: killing house sparrows is the second hardest thing bluebirders do. The hardest is finding bluebirds or their eggs or young in your nest boxes, destroyed by a house sparrow. Make that true for chickadees, as well.

Chickadee killed by house sparrow in nest box

So far we have had no luck catching the house sparrow. The trap was triggered once, but it was another chickadee and Dave released it. We hope soon to have materials to make the access hole smaller when we know we have chickadees nesting, so house sparrows can't get in. When you first put up boxes and are trying to attract bluebirds, you need to leave the hole bigger to accommodate the bluebirds you hope will start to use your nest box. And the size that will admit a bluebird is the same size that will admit a house sparrow, so that's a tough thing to deal with except by not putting up boxes where there are known to be house sparrows or in habitat that particularly attracts them. We have had occasional house sparrows here, but not very often. And we will certainly not feed millet or cracked corn, which are attractive to house sparrows, in the future as we sometimes have in the past. The millet is also attractive to some of our other favorite birds, like the white-throated and white-crowned sparrows that pass through here in the spring and fall, so it will be hard for us not to put out their favored food, but we won't. Note here a request: if you feed birds, please give careful consideration to not using the cheap birdseed mixes that contain a lot of the small, round millet seed, because by doing so you may well be inadvertently encouraging birds that kill other songbirds.

Here is a mini-documentary on the house sparrow, brought to my attention via Facebook from the blog Woolwine House Bluebird Trail:

I was feeling terrible on Wednesday (except for the almost simultaneous delight over the eggs in the other nest box), thinking that if we had not put up these nest boxes, that chickadee would still be alive. Then I realized that didn't really make sense. These birds are trying to nest -- they're not just nesting because we put up boxes. If they did not choose our nest box, the same thing could very well have happened in a nearby tree cavity, and probably does happen all the time. This is one of the reasons bluebirds, in particular, became scarce in the first place -- the double whammy not only of loss of habitat but also ruthless competition from these aggressive, non-native birds.

I've never particularly liked house sparrows, but I didn't particularly dislike them -- until now. I'll never look at a house sparrow the same again. I know they're just doing what comes naturally. But I don't want them doing it here.

Grackles Sure Are Here

noreply@blogger.com (Penelopedia) — 2012-04-06T18:12:00-07:00

I've noticed some common grackles around town lately, but I hadn't particicularly noticed any at our house. I got home after work today, though, and they had descended en masse. One was enjoying the new horizontal arrangement of a cage-type suet feeder, while others investigated our other feeders and the grass nearby. Many more were spread out some distance away on the neighbors' lawn. Altogether I counted about 50.

Grackles are quite handsome in their glossy, irridescent way, though they can be quite a nuisance to farmers and others with their large numbers and equally large appetites. They can appear to be black, blue, purple, green or bronze, depending on the light and distance. Their pale yellow eyes really stand out. Their long tail is another feature that makes them easy to identify.

We haven't had major problems with them in the past. Putting out safflower seed in the feeders for a while, which grackles and some other birds don't like, can be enough to send them on their way.

Right about this time of year in 2009 I commented on a grackle trying to be a feeder bird -- it was clinging to our caged tube feeder, which is for small birds like goldfinches and chickadees and is designed precisely to keep larger birds out.

Grackles can seem a bit thuggish as they stalk around, as if daring anyone to interfere. I expect they have a sense of safety in numbers, to some extent. However, after taking all of the photos here through my open car window, I opened the car door, stepped out ... and they were gone.

The March of the Coots

noreply@blogger.com (Penelopedia) — 2012-04-04T04:05:00-07:00

At Lake Byllesby on Sunday, while we also saw both blue-winged and first-of-the-season green-winged teals, northern shovelers and our first American white pelicans of the year, by far the most prevalent bird was the American coot. We first saw about 70 of the black, duck-like aquatic birds near us on the northwest side of the lake. Later, while scanning the lake through the spotting scope, we counted at least 200 more along one of the far shores.

The march of the coots -- moving steadily westward in the shallows

I was interested to see the nearby flock leave the swimming-depth water and move steadily across the wet mudflats (see photo above), where they probed the water (and perhaps the mud) for food with their bills, just as shorebirds like sandpipers do. I haven't seen this behavior in coots before. The impression of all these birds walking in one main direction was like a herd of migrating mammals.

Coots behaving like shorebirds

Although they look like small black ducks with pointed white bills, and they swim like ducks too, coots actually belong to the rail family (Rallidae). Other members of this family include the rails, sora and moorhens. Coots don't have webbed feet like ducks; they have large feet with lobed toes. They mainly eat aquatic plants although, as shown here, they also eat crustaceans, insects, snails and other small aquatic creatures.

More typical coot behavior at the Superior Drive pond in Northfield

Coots are very common throughout almost all of North America -- year-round residents in most of the south-central and western United States, far western Canada and most of Mexico, summer residents in the north-central states and Canada, and winter residents in the southeastern U.S., the west coast of Canada, coastal Mexico, and Central America. In the winter they can form huge flocks, measuring in the thousands. I have never seen that, but Sunday's sighting of 270+ birds at once was quite an impressive sight in its own right.

Bluebird Trail, Week One

noreply@blogger.com (Penelopedia) — 2012-04-02T19:13:00-07:00

This was week one of flying solo on our bluebird trail. We have 10 locations, six with paired nest boxes (#1-12) and four singles (#13-16), for a total of 16 boxes. Nest boxes are often paired to give bluebirds a chance to use one of the two boxes when competing species are present. I wrote more about this last year in a post about one of the most frequent of those competitors, the tree swallow.

New nest this week - one of the singles

The first pair is by our house, so we'll be able to keep closer tabs on these than the others, which are a few miles away but which we'll check at least weekly. This weekend's findings:

Empty
Very small amount of moss - this may mean a black-capped chickadee is starting a nest here. Bluebirds use grasses, primarily, but moss is a common component of chickadee nests. On Sunday the moss was fresh and green. Today it was dry and barely detectable.
Empty
Empty
Empty
Empty
Empty
Empty
Bluebird nest (read more at #10)
Bluebird nest. These bluebirds (at paired boxes #9 and 10) seem to be trying to have two nests! A week ago, one of these was well developed and the other was just being started. We have been advised that if we see eggs laid in both we should move them from the second to the first to consolidate them. Two pairs of bluebirds would not tolerate each other so close, so these must be the same birds, and they can't successfully incubate two sets of eggs simultaneously. We'll have to keep a closer eye on this set.
Empty
Empty
Empty
Starter nest - a tree swallow buzzed Dave agitatedly as he checked this box, so it's likely this is a tree swallow nest
Bluebird nest - new this week
Bluebird nest - new this week

In Bluebird Trails: A Guide to Success by Dorene H. Scriven (1993, Bluebird Recovery Committee of the Audubon Chapter of Minneapolis), the nesting sequence is described thus: It can take anywhere from one to six days to build a nest (the second nest in a season is usually built faster than the first). One egg is then laid per day, with an average clutch being four or five eggs. First-year females have smaller clutches (three or four eggs), while second-year females may have as many as six or seven. (The average lifespan of a bluebird, sadly, is only two years, though some survive several years longer.) Incubation usually starts as soon as the last egg is laid. The incubation period is 12-14 days. Young birds typically fledge between 18 and 22 days. It will be very helpful to keep this timing in mind as we monitor the boxes.

Dave returning a nest box after checking it

Starting Our Bluebird Trail

noreply@blogger.com (Penelopedia) — 2012-03-29T20:40:00-07:00

This year we're embarking on something new: bluebirds.

Female bluebird at McKnight Prairie in 2011

Eastern bluebirds have made a good recovery in recent decades, thanks to diligent and sustained efforts to help them successfully raise young by providing and monitoring nest boxes. Their numbers had previously diminished dramatically, owing to loss of habitat and nesting locations for these cavity nesters (birds that make their nests in old woodpecker holes and other tree cavities).

Male bluebird at McKnight Prairie in 2011

Recently Dave happened to make the acquaintance of Carroll Johnson, who is both a statewide coordinator and one of the Rice County coordinators of the Bluebird Recovery Project of Minnesota (BBRP). Carroll stopped by our house and agreed that our property, which is fortunately situated right next to some park-like private land on the far east side of Northfield, offers quite good bluebird habitat: an open, grassy area with occasional trees. So we've joined the BBRP, and Carroll brought us two PVC bluebird houses mounted on conduit over rebar. We put them up late last week while the ground was soft from the recent rains. Bluebirds are seasonal residents here and often arrive in March, though they may not start nesting immediately, so this is a good time to put up new houses.

Pair of nest boxes by our house

We have also asked if we can help monitor a few of the many bluebird houses being maintained in this area by Carroll and his fellow state/county coordinator, Keith Radel. (We're lucky that Rice County is the nerve center of the state bluebird organization!) Carroll and Keith each assigned us a few of their sites, and last Saturday morning Keith took us around to eight sites we'll be taking on near Northfield -- four pairs and four single houses. A set of monitored bluebird nest boxes is referred to as a bluebird trail, so these eight sites plus the ones at our house make up our first bluebird trail.

Cleaning out nest boxes

Agreeing to monitor bluebird houses is a serious responsibility. If you want to help the bluebirds raise young, you don't just put up nest boxes and forget about them; if you do, you'll probably end up raising house sparrows.

It's important to choose your location thoughtfully, check the nest boxes weekly, and keep detailed records of any activity at each box, including nesting, eggs and young, as well as absence of birds, use by other species, insect problems, and losses, so that appropriate adjustments can be made to increase the likelihood of future success.

It's also important to deter and if necessary remove house sparrows, a nonnative, unprotected species that aggressively competes for nesting locations and will evict and injure bluebirds if given the chance. House wrens are also very aggressive and will destroy the eggs and young of other species in their territories, which is one reason to locate nest boxes at a distance from wooded areas that are prime wren habitat.

So one key to having a successful bluebird trail is to learn to distinguish bluebird nests, eggs and chicks from those of other species that are also drawn to the same types of houses: tree swallows, chickadees, house sparrows and house wrens. That way you can tell what you've got in your nest boxes. Bluebirds: great! Swallows and chickadees: fine. House sparrows and house wrens: not fine!

A wren filled this house with twigs last year

On Saturday we cleaned out signs of wren occupation and one old bluebird nest. Bluebirds don't reuse nests, so it's good to provide a clean nest box each year.

Taking out an old nest - grasses, twigs and a few feathers

There are several kinds of nest boxes that allow the contents to be easily checked and cleaned. The boxes on our trail are all the Gilbertson PVC style. They are lightweight and detach from the roof for easy viewing and cleaning.

House taken over by wrens - filled with twigs

While we were out and about on Saturday we saw bluebirds near most of our nest boxes, which was a great sign, and we were very pleased to discover one new nest and the beginnings of another.

New bluebird nest -- a neat cup made mostly of grasses

We'll be attending the annual Bluebird Expo in Byron, Minn., on April 14, where I'm sure we'll learn much more from knowledgeable speakers and will get to meet other bluebird enthusiasts. I'll be reporting here on the successes as well as the inevitable mishaps or disappointments of our bluebird trail, so stay tuned for that. I'm just learning all of this, so I'll probably make some mistakes. I welcome corrections and other advice from more experienced bluebird fans.

Spring Has Sprung, The Grass Is Riz

noreply@blogger.com (Penelopedia) — 2012-03-26T17:48:00-07:00

With the recent almost surreal heat (80 F. last weekend at the end of a week of 60s and 70s), followed by some much needed rain and continued pleasant warmth, the first spring bulbs have come up and bloomed in one fell swoop: "boom and bloom," as my friend Mary over at My Northern Garden wrote. We've got daffodils, snowdrops, periwinkle and a lone crocus blooming at the same time at historically early dates, and forsythia is in bloom all over town. And the grass has turned beautifully green. All of these are extremely unusual for the third week or so of March. I took all of these photos on Friday.

Daffodils (Narcissus)

I thought I'd check my own records to see when these flowers have bloomed in previous years. So, here's a bit of spring flower phenology:

Last year on April 16 I noted that the daffodils had been blooming for several days when they got heavy, wet spring snow on them. In 2009 daffodil buds opened on April 17 and I noted that blue scilla were starting to show up in neighborhood lawns. I started noticing scilla today, March 23, looking as if they might have been blooming for at least a day or two already. In Jim Gilbert's book Minnesota Nature Notes (Nodin Press, 2008), which organizes nature observations by weeks of each month throughout the year, the section on daffodils and tulips is placed in the fourth week of April.

Snowdrops (Galanthus)

In 2008 I noted the first snowdrops (and a rainbow) on April 5. Snowdrops, as their name suggests, are often the first flower of spring, blooming as the snow retreats.

Periwinkle (Vinca)

In 2009 I described flowering periwinkles as "new growth" on April 22.

Crocus coming up through last year's maple leaves

I don't seem to have any previous posts mentioning crocuses -- probably because I don't remember noticing we even had one until perhaps last year. (When I took the photo above, I didn't notice the ant on the flower. Can you see it?) Jim Gilbert says crocuses usually start blooming by very early April, and he describes an early crocus blooming in a favorable microclimate despite snow on the ground on March 19, 2007 (Gilbert, p. 87).