1-30-13 Bird Field Note

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1-30-13 Bird Field Note

February 1, 2013

Kate Stone describes results from a survey using a custom iPad application to count and map over 500 overwintering raptors.

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Bird Field Note 1/30/13 A drab horned lark.

A mixed flock of gray-crowned rosy-finches and American tree sparrows scratch the ground looking for seeds.

The gray-crowned rosy-finches also seemed to like foraging on and beneath the tumbleweed carpeting a south-facing hill above Woodchuck Creek.

Debbie Leick observed a prairie falcon and a northern harrier battle for possession of the falcon’s gray partridge.

Scattered wing and tail feathers positively identify the prey as a gray partridge. DL

The US Fish and Wildife Services provides a useful resource, the Feather Atlas, for identifying flight and tail feathers.

In 6 weeks of surveys, we counted and mapped almost 500 raptors. Red-tailed and rough-legged hawks dominate the overwintering raptor population in the northern Bitterroot Valley.

Our spatial data show concentrations of individual species in certain areas. The Middle Burnt Fork area east of Stevensville has consistently harbored the highest concentration of raptors, though numbers appear to be decreasing as snow levels increase.

Red-tailed hawk and rough-legged hawk observations.

We expect to see an increase in bald and golden eagle numbers as calving increases throughout the valley.

We’ve seen most of our golden eagles in the vicinity of the MPG Ranch.

The male kestrels appear to show high site fidelity in the winter; we now anticipate seeing kestrels in certain areas.

We can only determine age for a few raptor species. Our data suggest that the overwintering population of raptors is biased towards adults.

The majority of raptors we detected were perched in trees.

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