2017 Recaptures

Recaptures (previously banded birds) are my favorite part of this project because it tells a story about the individual bird, about their dispersal, age, and sometimes other  information about their life history. This last spring we caught about 80 adult birds, half of them being recaptures.

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Tree Swallow 5/16/2017

Capturing adult birds requires proper timing to avoid inducing nest abandonment. It cannot be too early in the nesting stage, nor too late where chicks may prematurely fledge from disturbance. Even at the right time catching can be a challenge, since many of the parents are very vigilant and quick. Most of the birds don’t get captured, but out of the ones that do, we can get lots of great information from them! Here are photos of some our past season’s interns helping out with capturing adult birds.

The nestbox swallows of 2017 included a few birds that had bands indicating they were 6 years old, which is impressive for a songbird. While most Tree Swallows tend to return to the same or nearby site and/or box, there are some that dispersed a bit farther than others. The swallow with the largest dispersal for this year was a female breeding at Russell Ranch who was born at Old Davis Rd in 2014, about 10,500m away. This individual bird was one I had originally banded as an intern with other field members 4 years ago. I remember this because of the name we gave her as a nestling, “IP Man,” which we chose because we had just watched the movie the night before. This is one of the reasons why we like to name our birds when we band them, because when we recapture a bird that has a name, we can remember the individual bird instead of just a band number.

We were lucky to be able to catch a few Tree Swallow females on both their first and second clutches (after a successful first clutch) in the same box, confirming that some of the Tree Swallows were double-brooding. Tree Swallows are typically known to be single-brooders, but with help from the bands we can show that some of them were going for a second round.

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Tufty the Western Bluebird

Although not a recapture in hand, I wanted to mention our notorious color-banded bluebird whom I posted about on April 1st. He successfully raised another clutch this year. The 3 years prior to 2017, he successfully raised 2 broods each season. This year he raised successfully raised 1 brood, after a depredation event in his first clutch. The first year I saw him was the year I was an intern, and every year since I have seen him at the same box every year. He has raised about 30 chicks total over the 4 breeding seasons. He is a great-great-grandpa!

-Evelien de Greef

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2017 Season Brief Overview

This past season the Putah Creek nestbox highway has fledged almost 850 chicks! Once again, the Tree Swallows are the most abundant in number of fledglings, followed by House Wrens, Western Bluebirds, Ash-throated Flycatchers, and White-breasted Nuthatches. Other species we had in our boxes this year are House Sparrow and possible Brown-headed Cowbird (1-2 attempts each, unsuccessful).

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Tree Swallow

Our west-most site at the Interdam reach takes the lead on productivity relative to box numbers. We had more than 400 Tree Swallow fledglings total across 8 sites, and Interdam produced more than 1/5 of them!

Although the number of clutches was about the same (just a little lower this year) compared to 2016, the boxes produced about 80 more fledglings this season. Perhaps the winter flooding wiped out some predators (mainly rats), causing an increase in both number of eggs as well as an increase in hatching and fledging success rates. The flooding could have also helped by bringing in more insects for food for the nestlings.

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Putah Creek – picnic grounds

Another notable difference this year was a lower number of Ash-throated Flycatchers using the nestboxes (about half as many as last year). The ATFL nestbox numbers aren’t usually high anyway, but dropping from 20 nesting attempts last year to 10 attempts this year is a bit surprising.

More details regarding the 2017 season coming soon.

On a side note, the UC Davis Arboretum (separate from the putah creek nestbox highway) was filled by Western Bluebirds this year. It looks like the bluebirds are making themselves quite comfortable at the oak grove section of the Arboretum. Over the past few years, they’ve been filling up more and more of the previously unoccupied boxes.

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Male Western Bluebird

-Evelien de Greef