Tuesday, July 01, 2008

The Kestrel Report

For the past two years I have been working local bird researcher Bob DeCandido to shed some light on this diminutive and secretive raptor. Faced with precipitous declines all across North America, it seems this plucky raptor can count New York City as one of its strongest population centers. In Manhattan alone there appear to be approximately 24 active nests, while the total for NYC as a whole is approximately 100-150. Each of these produce between 2-4 young in a clutch, and many of them lay 2 clutches per year. That means somewhere between 400 and 1200 young kestrels are produced each year. This raises several obvious questions:
1) Why are they doing so well here and declining so rapidly elsewhere?
2) If so many kestrels are being produced annually, Where are they going? and What is their survival rate?
3) What can be done to stabilize the population here in the City so that they may replenish other areas that are declining?

In this and some following posts I will reproduce many of the newsletters, photos and correspondences I've had with Bob as well as other kestrel watchers from around the City. Also below you'll find an email from NJ documenting the problems kestrels are facing there, just across the river.

"Hi Dr. X,

I am just emailing to get more info on where I can read the American Kestrel newsletters for the populations that you monitor. I am a grad student at Montclair State University and am doing my thesis on American kestrel vocalizations with Dr. John Smallwood, who has around 100 boxes up in northwest NJ. Since 2002 the kestrel populations we have been monitoring have been in sharp decline. In 2002 there were around 60 pairs and each year the population has gone down with an all time low this year of only 19 pairs. I am just curious to know if the population of kestrels that you are studying has been stable or declining as well, and also where your boxes are in NYC, in all the 5 boroughs? Any info you would be willing to share would be much appreciated!


Erica Mueller"

What is interesting to note is that here in NYC there is actually NO kestrel nestbox program...Instead, the kestrels favorite nest location is the rusted out cornices of mid-level buildings. Despite this obviously tenuous nest choice, they seem to use these to great advantage in keeping their scrapes secret. As for what may be reducing their numbers elsewhere, a variety of factors are suspected including: habitat loss, increased predation by other raptors, declining food sources and perhaps environmental toxins. But the fact is no one really knows for sure and it may be that time for this beautiful raptor is running out. Only by establishing a concerted research project can the preservation of this species be prioritized as there is currently a dearth of both literature and research on to the causes of their decline and the possible ways they can be augmented.

photo courtesy of Deborah Allen

More postings on kestrels in a bit!

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