Bluebird Trail, Week 13 - Fledging Tree Swallows

Much of the action in the bluebird boxes lately has been from tree swallows. A couple of broods of house wrens have also fledged.

Sadly, about two weeks ago we lost the first brood of our second-round bluebird nestlings at just a few days of age. We had seen them as new hatchlings, but they were all dead in the nest when we returned the following week. We can only presume that something happened to the mother (possibly in the day of big storms that hit Northfield that week, though based on the nestlings' development we think it was probably a couple of days earlier) and the little ones perished without her. As we understand it, while the males help feed the babies, they do not enter the nest and brood them to keep them warm, which they need until their feathers come in and they can regulate their own body temperatures. So they really need their mothers for the first week or more. It was quite a shock -- our first bluebird casualties.

However, the tree swallows have given us much to observe, as the photos below reveal.

In the first photo are six tree swallow nestlings a few days from fledging. They are certainly crowded in the round Gilbertson nestbox, but all the tree swallow nestlings we've seen seem to figure out that heads pointing out is the best arrangement. We have not lost any tree swallow nestlings to overcrowding, though we understand that it can be an issue since they have larger broods than the bluebirds do.

Six tree swallow nestlings

In the next photo, tree swallow nestlings approaching fledging age were peeping out of their box, awaiting food.

Tree swallow nestlings looking out at the world

This past weekend we checked a box where we were pretty sure fledging would already have occurred, and we found two nestlings were still in the box. We must have caught them on fledge day -- or perhaps it took a day or two for all the birds to fledge. Dave checked again the next day, and they were gone.

Fledge day - two left

And here (below) is a shot showing the remarkable construction of the tree swallow nest, revealed when we cleaned out a nestbox after tree swallows (the ones peeping out in the earlier photo) had fledged. We found an unhatched egg in this nest -- in this one case, we'd never been able to get a final count of the eggs before hatching, so we were not aware until the end that one had not hatched. This was the location where I got the lovely photo of the mama incubating, surrounded by white feathers.

Tree swallow nest after fledging

Unlike bluebirds, which typically raise two or sometimes even three broods in a season, tree swallows are usually finished after one brood, though there are exceptions. (The tree swallow page on Sialis.org has more good information about tree swallow nesting and development.) So the nestboxes that are gradually being vacated by the fledging tree swallows will become available for bluebirds or other cavity nesters that are ready to lay again at this point in the summer, and the tree swallows will not compete for those nesting locations unless their first attempt has failed.

We try to clean the nestboxes out as soon as we confirm that fledging has occurred, to ensure a more sanitary and pest-free setting for the next nest (tree swallows leave pretty dirty nests by the time they're done), but it's been amazing how quickly a new tenant can move in. We recently came back to one nestbox intending to clean out a vacated tree swallow nest, only to find a complete new bluebird nest with an egg in it already, built right on top of the tree swallow nest.

Cecropia Moth in Downtown Northfield

This enormous, strikingly patterned moth was hanging out amid the flowers and greenery in a concrete planter outside my workplace in downtown Northfield. It looks like a Cecropia moth, which is North America's largest native moth according to Wikipedia. My Golden Guide to Butterflies and Moths puts the wingspan at 4.0-6.3 inches.

Dickcissels

Until this month, I'd never seen a dickcissel. What a beautiful little bird! Very like a meadowlark but considerably smaller (about 6 inches long), they are washed with yellow on the breast and in a streak over the eye, have chestnut wings and a bluish bill, and the mature male has a prominent black V on its chest (first-year males look more like females).

Male dickcissel

The yellow is more brilliant in the male, but the female has a lovely, soft yellow cast to her. The flash of yellow, the chestnut wings and the black markings on the male all help distinguish these birds from the varied sparrows that are also common in grassy areas. Meadowlarks are noticeably larger (7.5 to 10 inches long), have a longer, thinner bill, and the yellow extends all the way down their bellies.

Female dickcissel

Dickcissels are grassland, seed-eating birds that breed in the Midwest and congregate in huge groups in migration and their tropical wintering grounds, where they may be regarded as agricultural pests. They nest close to the ground in shrubs, saplings or grassy clumps. Learn more about dickcissels at the All About Birds site.

We've been seeing dickcissels since early June at the McKnight Prairie, northeast of Northfield in Goodhue County, and have heard they've also been seen recently at grassy areas in the Carleton Arboretum and other nearby locations. Wikipedia notes that they arrive fairly late at their breeding grounds, with most arriving only in early June. Given the date, then, the photo above is most likely a female rather than a first-year male. We have been going to McKnight regularly for several weeks, and the dickcissel's arrival was unmistakable on our June 3 visit, due to its loud, distinctive song that we certainly had not heard earlier. On June 3 we were only sure of one individual. On June 13 we saw and heard several; they seemed the most prominent bird of the day.

Male dickcissel

Male dickcissel singing

Here is a short clip of a dickcissel singing:

The Deluge in Northfield - Video

The big event of the week in Northfield and the nearby region was the six to eight inches of rain -- even more in some spots -- that came down on Thursday. Wave after wave of heavy rain passed through the area throughout the day and well into the evening. The Cannon River flooded in Cannon Falls, along with the Little Cannon, but did not (at least not to any significant extent) in Northfield. However, creeks overflowed, soccer fields turned into lakes, farms were underwater, several roads became impassable, and many people had wet basements.

I have a wet basement myself -- our sump pump failed at one corner of the finished portion of our basement, so water welled up in that area and spread throughout our family room. More water poured in under a door at the opposite, walk-out side of the basement, where there is a badly conceived exterior stairwell. We have a bedroom down there as well, which is also very wet; it seems to have received some water from both sources. We spent much of the night trying to keep up with it all, and quite a bit of time and hard work ever since, trying to get things dried out and assess what needs to be done next. Carpets, baseboards and the bottom of several walls were soaked. It's been quite upsetting, but I know that what we experienced was little compared to some others.

Friends at the small, diversified Seeds Farm and Laughing Loon Farm, just south of Northfield, were indundated. Much planted acreage and some chickens were washed away. Both farms are gratefully welcoming volunteers to help with the clean-up this week. Both have Facebook pages: https://www.facebook.com/LaughingLoonFarm?ref=ts and https://www.facebook.com/SeedsFarm?ref=ts. I've been following both farms' accounts of their spring plantings, and it's very sad to see so much hope simply drowned, though I'm sure they'll recover in time.

While watching one of the early downpours from the Neuger Communications Group office at the heart of downtown Northfield, I took this short video of water lapping over the curb in front of our building and gushing from a manhole across the street where the storm sewer became overwhelmed. It's funny to think, looking back, that this was only the beginning. At this point in the day, the planners of Taste of Northfield were still hoping to hold the event that evening, "rain or shine." In the end, of course, it had to be canceled.



A couple of local websites picked up this video (which, due to the magic of the smartphone, I had posted to YouTube and tweeted within a couple of minutes of recording it), and when I checked yesterday I was quite astounded to see it's had more than 800 views.

While coping with all the rain, we spared a thought for the close-to-fledging tree swallows in some of our bluebird boxes and hoped that they were staying dry and had not chosen that morning to leave the nest. And I hope our young bluebird fledglings, most of whom are only two or three weeks out of the nest, found shelter and are all right. We checked most of our nestboxes yesterday, and all those we checked seemed to have stayed dry. I'll be posting a bluebird trail report soon.

Update - June 18: We had another bout of heavy rain and hail overnight -- Weather Underground stations are reporting between one and four inches overnight in the Northfield and Cannon Falls areas (3.75 at Stanton airport).