Foreign Recovery, Clutch Sizes and Hatching Imminent

Since my last post, the kestrels have been diligently incubating eggs, fighting off unruly starlings and tolerating my occasional intrusions into their homes. It must be disconcerting when a large, foreign object (usually a coconut water can on a pole) blocks your front doorway. But they continue tending their clutches with biological determination. Unfortunately, a couple of pairs have abandoned boxes due to the intense competition with starlings in this area. I will probably move a couple of the boxes next year to areas where these pesky, non-native birds are less abundant. 

I finalized my inventory of all the occupied boxes for complete clutches (total eggs laid). From 11 occupied boxes, a total of 54 eggs have been laid. This comes to 4.91 eggs/occupied box. I suspect a small number eggs won't hatch, so I'll maybe have 50 nestlings to band. Should be fun. 

I've also banded a few more adults, which can be seen in the following photos. I trapped the first male near his nest box just west of New Paltz, where he is doing a stellar job providing for his mate and hopefully raising 4 young kestrels in a few weeks. Interestingly, he was a foreign recovery, which  means another bander put a band on him elsewhere. After submitting the band number to the Bird Banding Laboratory, the clearing house for all bird bands issued in North America, I learned that elsewhere was near Mechanicsville, PA. That's roughly 105 miles SSW of his new home. He's roughly a year old, originally banded as a nestling in mid-June. A new house, girlfriend and kids on the way all before his first birthday...impressive.

Second-year male, west of New Paltz

This female was gently lifted from her nest box during incubation duties on 9 May. I got her banded, measured, photographed and back inside in 10 minutes so she could resume tending her 5 beautiful eggs. Many thanks to local birder Karen Maloy Brady for kindly snapping this excellent photo.

Breeding female and humbled human. She is NOT smiling.

The next shot was taken of a female caught today at another box south of Gardiner, NY. I'm attempting to blow feathers out of the way to expose her brood patch. Birds that are incubating eggs develop this featherless area on their bellies so as to provide the eggs with the necessary warmth for embryonic development. The brood patch is rich with blood vessels to facilitate the transfer of heat from adult to eggs. The eggs can tolerate periods without incubation, but the temperature needs to remain between about 35 and 38°C (95-100°F). Interestingly, the temperature at which any given egg is incubated determines the sex of the nestling that emerges from the egg. Biology... SO COOL!

Female Brood Patch

When I got up this morning, I had two boxes where final clutch size was still unknown. I confirmed both had 5 eggs and had the lucky bonus of banding a male at one and a female at the other while they incubated. Below is the male from one of 6 occupied boxes in place on the Shawangunk Grasslands NWR. This is the second time I've encountered him in the box during nest checks. I did not band him the first time since the clutch was not complete at that time. Today was a different story and he received a nice color band that will hopefully be re-sighted during the non-breeding season and provide some information about migratory and/or wintering habits. 

Responsible male at SGNWR...today

Hatching will begin any day now, so I will be counting many fuzzy kestrels over the next few weeks. Adults will be ramping up their hunting efforts to fill hungry beaks. Stay tuned.




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