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Posts categorized Kestrels.

Summerhill Preserve Kestrels 2015

American Kestrels in the nest box

American Kestrels in nest box
(photo – Ron Zigler)

By Mike Coll Preserve Manager

For the second straight year, the nest box at our Summerhill Preserve successfully fledged American Kestrels. This year there were four young.

This video shows one of the adult birds flying up to the box to feed the young (in slow motion):

Here you can see the young birds inside the box. They fledged from the nest less than a week after this video was taken:

Read more about our nest box installation at Summerhill Preserve (one of our nature preserves open by appointment) and the Kestrel population there in this June, 2014 blog entry.

American Kestrels Return to our Stroud Preserve

By Mike Coll, preserve manager

American Kestrel, Ron ZiglerThis year for the first time the walking trail through the “Bobolink Meadow” at our Stroud Preserve was closed to foot traffic during bird breeding season (April-August). This trail closure is one of a number of such closures aimed at protecting the breeding grounds of sensitive bird species. In this case the impetus for closing the trail was the breeding population of Bobolinks, a species that consistently nests in the grasses of this particular meadow. These ground-nesting birds can be negatively impacted by the proximity of humans and dogs (especially unleashed ones).

However, closing the trail appears to also have had a positive impact on another species in decline, the American Kestrel. Kestrels are also easily disturbed by humans and, although a box had been present for a number of years, I had never observed Kestrels nesting there until this year. The trail previously came almost directly beneath the box and likely was the reason they hadn’t used it.

Here is a video of the young birds (looks like 4) at just a few weeks old:

Mariton: New Nest Box

by Tim Burris, Preserve Manager

Kestrel box with bat box in the background

Kestrel box with bat box in the background

If you are up in the meadows you may notice a new addition. Last week, Josh and I put up a new Kestrel nesting box at Mariton. We used a dead Eastern Red Cedar (Juniperus virginiana) for the post. I keep track of locations of these trees as they eventually get shaded out in the forest, and are very rot resistant.  We kept the post above the box to provide a perch for hunting.

Josh setting the post.

Josh setting the post.

We used the truck and a ladder to install the box and a baffle.

We used the truck and a ladder to install the box and a baffle.

Kestrels were called “sparrow hawks” in the past, but they also feed on a lot of insects.  If a pair settles into the nest box, they should be able to find lots of food in the meadows.

Kestrels at Summerhill Preserve

A new Kestrel nest box at the Summerhill Preserve successfully attracted it’s target species in the first year.   The box was mounted on a natural cedar post by FON volunteer Brian Bernero.  Installed, the opening of the box sits approximately 14 feet above the ground in a warm-season grass meadow.  I wrapped metal flashing around the post to prevent predators from climbing up into the box.


A pair of Kestrels found the box almost immediately in early April.  I observed the male sitting on the box with the female in a nearby tree.

A few weeks later towards the end of May I reached a camera on the end of a pole into the box and took this picture.

The fact that the female (pictured) did not leave the box when I approached it told me that she was likely incubating eggs.

A few weeks later on 6/12 I returned to take this picture showing some newly hatched falcons, probably 7-10 days old.


This week (on 6/25) I returned again to the box.  As I approached I could see the head of one of the young birds poking out of the hole.


Less than 30 days after hatching, young Kestrels weigh as much as their parents.   These 5 fledglings have grown most of their flight feathers and are nearly ready to leave the box.  Once they leave the nest their parents will continue to feed them for a number of weeks as they learn how to fly and become effective hunters.  All of them must race to become self sufficient before the fall when they will most likely attempt their first migration.

Kestrels at Hildacy

Mike Coll, Hildacy Farm Preserve Manager

The American Kestrel is North America’s smallest falcon.  It is a cavity-nesting bird that lives in open areas like meadows. Because grassland habitat has decreased in this part of the country and because there are few old dead trees left standing that could provide cavities, Kestrel populations have shown significant declines in recent years.

I put a nest box on a post in the upper meadow at Hildacy about three years ago. While I had previously seen Kestrels sitting near the box at the beginning of breeding season, it wasn’t until I moved the box further into the interior of the meadow this year that a pair decided to take up residence.

With the help of volunteer Ron Zigler, I was able to capture this video of the young birds when they were about two weeks old.  It is tough to tell if there are three or four birds in the box, but since then they all have successfully fledged and I’ve seen them sitting in the trees surrounding the meadow.

Ron recently completed a study of kestrels nesting at our Gwynedd Wildlife Preserve… check out that blog post, too!



Kestrels At Gwynedd Preserve

By Ronald Zigler, volunteer at Gwynedd Wildlife Preserve in Ambler, Pa.     

All bird photos are the property of Ron Zigler and were used with permission.        

                                 IMG_1024-Edit         IMG_1898-Edit

My interest in Kestrels emerged from an interest in both birding and my hobby of bird photography. Kestrels are the smallest and most colorful raptor of America and are part of the “family” of birds known as “falcons.” They are about the size of a Blue Jay, but very difficult to approach and, hence, rather challenging to photograph. While sometimes called a “Sparrow Hawk” Kestrels are more closely related to the Peregrine Falcon than to the smaller members of the hawk family. In many ways, “Sparrow Hawk” is a misnomer since their diet consists almost overwhelmingly of insects. However, Kestrels will hunt small mammals as well as toads or lizards. On occasion, they may take a small bird if the opportunity presents itself. One of the photos I was able to capture of a male Kestrel at the Gwynedd Preserve this spring shows him on the top of a fence post with a vole. Kestrels need to supplement their diets with these small mammals during the winter months when insects are not available.


Some, but not all Kestrels will migrate south during the winter. Often a male Kestrel will remain in the territory of his established nest and defend his territory year round. Early in the spring when I began observing the Kestrels at the Gwynedd Preserve, I often noticed the male perched on his nest box. It was not until later that I observed a female Kestrel who had dropped by to inspect the nest box. It looked as if he was trying to impress her with the new nest box that had been set up there.

Kestral Pair IMG_1006

Kestrels adapt well to man-made nest boxes since they are cavity nesters. They do not create their own cavities, however, and have traditionally nested in tree cavities. In the 1990s, there emerged a growing effort to set up nest boxes for Kestrels in order to compensate for the development that had reduced their traditional nesting sites, which resulted in a drop in their population. By the end of the 90s, the birds began to rebound as they proved themselves highly adaptable to these nest boxes. However they do often compete with Screech Owls and Starlings for these sites.

While Kestrels are not endangered, their numbers have once again declined somewhat in recent years. The reason for the decline is not clear. This is, however, one of the reasons why the American Kestrel Partnership was established—to set up and monitor Kestrel nest boxes so that we may help wildlife biologists around the country collect data on both successful as well as unsuccessful nest boxes. 


Gwynedd Preserve Manager Tom Kershner took this photo of me using an infrared camera mounted on a pole to monitor the Kestrel nest

The Partnership has emphasized that much is learned from either outcome. Unsuccessful nest boxes can help researchers understand the threats that Kestrels are encountering. This spring, the Kestrels at Gwynedd were clearly successful, and the activity, which was monitored, was typical of their mating cycle. Usually, 4 to 6 eggs are laid around the end of April or early May (the Gwynedd nest box had 5 eggs, but only 4 hatched).


The eggs are then incubated for about 28 days after which the nestlings will hatch. 


Another 28 or 30 days later, the young birds will fledge, looking like somewhat smaller adult birds with the distinctive plumage of the male and female Kestrel.


Next year, we plan on having a second nest box set up the recommended one half mile away from the nest box that was occupied this year. We look forward to increasing this bird’s presence on the preserve all year long.

Empty Nest IONX0001-2

The Kestrels have fledged the nest. The unhatched egg is at the bottom of the frame.



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