05-30-14 Bird Field Note

05-30-14 Bird Field Note

May 30, 2014

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By: Kate Stone and more...

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Kate Stone and William Blake's Field Note describes long-eared, and great horned owl nest monitoring, plus satellite transmitter deployment.

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Field Note Kate Stone William Blake 5/30/14

Phenology and fate of Long-eared Owl nests We found five long-eared owl nests this spring (O). We found two Great Horned Owl nests as we searched (O). We targeted the Long-eared Owl females for transmitter deployment.

WB We captured eight Long-eared Owls and deployed satellite transmitters on four females. Even though we trapped at two nests used last year, we did not recapture the same owls. Here Kate and Shawn prepare the female from Becca Draw for her transmitter.

It takes time and fine-tuning to ensure the transmitter fits. Kate and Shawn adjust the harness and then apply glue over the knots that secure the unit.

We checked nest contents since we already disturbed Becca Draw nest. On 5/15/14 we saw four nestlings and one unhatched egg.

By 5/22/14, nesting neared completion; only two active owlets remained in the nest. We heard the clicks and hisses of at least one “branchling” nearby.

We attached three of the four transmitters at night.

We used a thermal imagery device to watch this female’s release in the dark. We observed her unimpaired flight ability. We can re-capture incubating females if a problem with transmitter fit or performance arises.

We found a new Long-eared Owl female on a stick nest in a mistletoe infested Doug fir in section 16, near recent thinning activity.

The male roosted within feet of us as we set up mist nets.

The female from the Sweet 16 nest ignored our mouse bait, possibly because females hunt less in early incubation. We will attempt to trap her again next week. Curiously, we caught two males at the nest. William took a bite from one as we we processed the pair.

UV light illuminates molt patterns hidden to the naked eye in a male owl’s wing. Newer feathers fluoresce pink.

After transmitter deployment, we checked on the owls to make sure they stayed with their nests. At the Road Junction nest, “Loretta” continues to incubate. Light penetrates the canopy to her nesting site. Sunlight charges her transmitter while she incubates in full sun.

A week’s worth of data show that the transmitters charge and generate points that cluster around the nest sites.

We found the Great Horned Owl nest in the Upper North Draw empty a few days ago. Abundant whitewash and fuzzy feathers in the area suggest that the owlet fledged.

We found a new Great Horned Owl nest (Road Bend) in a large mistletoe clump. We spotted the roosting adults as we drove by.

Only one owlet occupied the nest.

During spring shrubby draw surveys, we consistently flushed a Great Horned Owl in lower Partridge Alley, near the Turn Around. We have not found a nest.