06-29-15 Bird Field Note

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06-29-15 Bird Field Note

June 29, 2015

The end of June bird field note details fledging raptors, Northern Pygmy-Owl research, and American Kestrel tracking.

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Bird Field Note Compiled by Kate Stone 6/26/15

The Bald Eagles at both local nests are close to fledging. One eaglet has made repeated movements off of the nest near the Clubhouse (top). The lone eaglet across the river has yet to venture far (bottom).

Eastern Kingbirds are one of our feistiest passerines. They challenge creatures of all sizes, including an adult Red-tailed Hawk.

3 When not fighting, kingbirds often use our exclosure materials for perching.

Our first documented Viceroy butterfly flitted around the northern floodplain.

Chipping (top) and Vesper (bottom) Sparrows are busy bringing food back to nestlings.

Our Northern Pygmy-owl nest fledged some time between 6/19 and 6/23. In the days prior to fledging, the cavity entrance was constantly filled with the curious head of a nestling.

7 We recorded video footage in the days prior to fledging. In our limited video, the female made all deliveries to the nest. Baby birds were the most frequently observed prey item.

Two audio cues indicated an imminent prey delivery: a twittering begging call from the nestlings, and a cacophony of alarm calls from the resident birds.

The female usually entered the cavity with the prey item. Here she sticks her head out in response to an inquisitive and alarmed Red-breasted Nuthatch.

This week we captured the pair of American Kestrels using the nestbox near the Indian Ridge cutoff road. They were the last kestrels to start breeding. While the young at some nests are getting ready to fledge, this pair is still incubating.

We outfitted both American Kestrels with PinPoint GPS units. We’ve put eight of these transmitters out so far.

The oldest kestrel nestlings are within days of fledging. These four chicks were raised by AK-62, the first kestrel we equipped with a PinPoint GPS unit.

We found a Tree Swallow nest in one of our kestrel boxes. Tree Swallow eggs (above) look tiny compared to the American Kestrel eggs (below).

The Red-tailed Hawk nestlings on the northern floodplain fledged earlier than we anticipated, and had already left when we arrived to band them. Gus Seward scaled the large Ponderosa Pine nest tree. He removed many dead limbs, which will make the nest safer and easier to access in future seasons.

After several days trying to trap the young with pigeons, starlings, and mice, we finally caught and banded this male.

Boisduval’s Blue

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06-23-15 Bird Field Note