Kestrels as Cavity Nesters and Predators of Other Cavity Nesters

Also see Hawks/Owls as cavity nesters or as problems on the bluebird trail

You all have read my posts about getting up and enjoying the mob of 11 bluebirds playing and flitting between the boxes in the fall season. Well, I was watching them two days ago and down comes Mr. Chicken Hawk/Kestrel after them, landing on the box and then circling them as they dispersed, me running out there screaming in my PJs again. Sheesh. I haven't seen or
heard the bluebirds since. I hate this. I certainly can't shoot the
kestrel and I want to protect the bluebirds. I had this same problem last year when they were nesting and lost the male/father when the bluebird chicks were young and one of the juveniles of the previous clutch who was
trying to help the female/mother bluebird feeding them by herself. The
kestrel has figured out that those boxes in the open are feeding stations.
It irks me that he doesn't hunt the flocks of starlings, but tracks down the bluebirds.

Big sigh,
Autumn in Kentucky

-----Original Message-----
From: Evelyn Cooper [mailto:emcooper"at"bayou.com]
Sent: Thursday, October 20, 2005 7:46 AM
To: autumnk"at"iglou.com; bluebird-l"at"cornell.edu
Subject: RE: Dagnabbit! Kestrel after bluebirds again!

I have mentioned this before to the List. I have a Kestrel that migrates to my place every year. I saw him two days ago in the same place he usually stays on the power line on Cooper Rd.

The thing that amazes me is the Bluebirds and other birds perch on the line just a few feet from him and I see it nearly every day. I think maybe he searches for other types of food as I don't think they would sit that close to him if they were afraid. He/she is one beautiful bird. When I drive up the road, it flies along in front of me, then circles back and lands on the power line.

I read an article in "Bluebird" about Kestrels and Bluebirds nesting close together on someone's trail. I still have it and will look it up.

If the Kestrel was hungry enough, he probably would snag a smaller bird.

Evelyn Cooper
Delhi, LA

The American Kestrel is the smallest falcon in North America. They *are* cavity nesters (& therefore OT) & will readily take to boxes. They hunt primarily insects, small mammals, & reptiles, but do hunt larger things when they're feeding young during the summer.
Birds are pretty rare as prey items. The male has got very noticeable blue wings, but the female is bigger.

Kestrels hunt the same way bluebirds do -- They mostly perch & watch & then fly down. They will also hover, which is very distinctive, over areas where there's no good perch. The similar hunting style means they like similar habitat -- Open with scattered trees & relatively short grass.

Kestrels from Canada & the northernmost states do go south, but southern birds stay put. Females migrate before males & pick out the best wintering territories, but they both return to the same breeding territory.

The average kestrel is 9" nose to tail, has a 22"
wingspan, & weighs 4.1 oz (117 g). The average Eastern Bluebirds is 7" long, has a 13" wingspan, & weighs 1.1 oz (31 g). A kestrel killing a bluebird would have to be able to fly off carrying one-quarter its own weight, which is not likely. They are not a serious threat to any of the 3 bluebird species.

All of the other falcons (most have a similiar face pattern, but none are blue-&-rust) hunt birds, either in level chase flights or stooping from high above.
Sharp-shinned Hawks & Cooper's Hawks (both accipiters) are widespread throughout North America. They hunt small birds & are very agile while pursuing them thru trees & bushes. Bird-hunting raptors oftem migrate right behind songbirds, which may be why so many songbirds migrate at night.

Torrey Moss
Kalamazoo Nature Center
Kalamazoo, MI

I am smitten with this little bird. If you have not seen Don McCartney's
pictures of them on our site, you will enjoy them. He raises them on a trail
in Oregon. He fledged around 200 this year.

Evelyn Cooper
Delhi, LA
Louisiana Bayou Bluebird Society
Affiliate of NABS
Member, NABS
www.labayoubluebirdsociety.org

My problem is they perch on the board fence and wait for the bluebirds.
I've witnessed with my own eyes them snatching bluebirds on 3 occasions; more than I can count when they tried and were not successful because I ran screaming across the field in my jammies. I know that's not PC, but it's
the truth. They seem to have a taste for bluebirds. I have habitat for
them both and can do nothing but run them off in when they target the bluebirds. Like all falcons/hawks, they are very sharp and know where their food sources are apt to be found.

I so wish they'd acquire a taste for starlings.

Autumn in Kentucky

I can certainly understand your frustration if they Kestrels seem to only be after your Bluebirds in search of food. According to Torrey's post and all that I have read about the Kestrel, this is pretty unusual behavior.

For the last two years, my backyard blues have continued to visit the feeder and take a raisin or two daily. This did not happen in subsequent years.
They would ignore the raisins even if they were there and seek the insects that are their favorite.

This just shows that there are individual birds that deviate from what is considered the norm. Looks like that is your situation.

I don't know what to tell you to do as the Kestrel as you know is protected by law. I run out screaming at the Mockingbird in my backyard every spring because they are harassing the bluebirds off their nestboxes, (trying to run them off and keep them from nesting there). I guess this is against the law, (considered harassing them) but maybe nobody will put us in jail for yelling and screaming at those that aggravate and/or kill our bluebirds.

Evelyn Cooper
Delhi, LA

Torrey,

I happened to see your note. It is a good statement on kestrels but for one part -- to wit:

"They are not a serious threat to any of the 3 bluebird species"

I guess it depends on what you mean by "serious". If you mean "usually" -- I would agree almost 80% of the kestrel diet is insects in some environments -- genially less than 10% is avian.

But make no mistake a kestrel is fully capable of killing, carrying off, and eating a Bluebird (and any similar sized bird) and from time to time they do take Bluebirds -- this is well-documented.

Consider that the Am. Kestrel can just as easily carry off a Bluebird as the similar sized Sharp-shinned Hawk can. After all a kestrels prey heavily on mice (old world and new world species) and both Mus or Peromuscus spp. can easily equal the 30 or so gram weight of a 30 gm Bluebird. No sweat for them to carry 30 grams.

The Sharpie is even known to kill the prey much large that Bluebirds and some European Starling kills have been observed -- and of course 90% of the hawk diet is avian in contrast to the falcon.

Bernie Daniel

BTW -- But I do love kestrels also and their current decline is troublesome -- some evidence that it may be related to Cooper's Hawk increases.

In "Bluebird", Summer issue 2005, there is an article on Kestrels by Dan Ardia, with the Department of Ecology and Evolutionary Biology at Cornell University.

He states that Kestrels catch and kill prey such as mice, lizards, snakes and birds and beasts almost as large as themselves.

The article talks about the Kestrel being predated upon. It states that both male and female have “false eyes” on the back of their heads. These small patches may look like eyes at a distance and thus give the predator the impression that the Kestrel is looking its way.

I have more lizards, mice and snakes than I do Bluebirds, so maybe that is why they are sitting on the power line together. I hope so.

Evelyn Cooper
Delhi, LA

Bernie, I think Torrey meant what you elaborated, but thanks for relaying your points b/c everyone else might not have known all of the highlights you pointed out.

The kestrels I've observed predominantly stick to rodents, insects, and small reptiles. But, when one gets really hungry, or the opportunity presents itself they'll take another bird in a second. I've seen one take a mourning dove, which is larger than itself.

I believe in this case of one taking blue's, it's just one that found an opportunity. The blue's haven't yet learned to avoid and evade well enough.
The kestrel won't "waste" time trying to take them unless it's having success. Like many have said before, it's not pleasant to us b/c we have keen interests in blue's. But then again, it's nature -- if the blue's aren't "good enough" to get away, or the kestrel is just that keen at hunting, then it's normal. Kestrels lead pretty tough lives, in many cases having life spans shorter than or equal too many small migratory songbirds.
It's got to earn a living too.

Hope everyone had a good weekend. --J

Jimmy Dodson
Asst Forest Manager -- NCSU Dept of Forestry NCSU Hill Forest P.O. Box 71 Rougemont, NC 27572

Torrey,Bernie,Jimmy and list,

When I was a youngster I had no clue what a Kestrel was,where I live
it was called a Sparrow Hawk. This was the only Hawk that the farmers in my
area did not shoot because they realized the benefit of their presence. As
Bernie and Jimmy both stated mice and insects are the Kestrel`s main diet
,but small birds are definitely part of the menu.

www.abirdshome.com/audubon/voll/00034.htm

Jimmy,

I agree with your comments.

There have been reported cases of kestrel specializing in raiding or trying to raid nest boxes. Most birds of prey develop particular hunting patterns that are largely a function of what happens to "work" for them.

I think we should all do everything we can for kestrels. They are cavity nesters which makes them dear to this list-server group. What is more they seem to be under a lot of stress in wide sections of their range these days.
Some have recently published evidence, based on surveys, that the declines in American Kestrels are correlated with increases in Cooper's Hawks.

Might be something to it. Coops are definately on the increase. For many years now I have worked in collboration with group of scientists studying Red-Shouldered hawks in S.W Ohio. Over the last 7 years we have identified over 100 nests and are tracking many of them --- but one thing we are finding more and more frequently are Cooper's Hawk nests. In fact I now have one almost in my back yard. The chicks often take a bath in my lawn
sprinkler in the mornings. -- Bernie

From: Snoopy [mailto:snoopy"at"wmis.net]
Sent: Monday, May 15, 2006 12:56 PM
Subject: my NEW friend!

I looked out my back window this morning and saw a "new" bird I'd never seen before.

So I looked it up in my guide to N. America birds and it's a female AMERICAN KESTREL....

The book says it preys chiefly on House Sparrows!!
Prey away dearie.... eat them ALL!!!!

=D

Anyone here ever had them NEST in their yard or nearby?
I guess what I want to know is is there is a way to KEEP them here for good???
I can use all the help I can get getting rid of HOSP.

Joy in Cedar Springs, Michigan

Hi Joy,

You have a beautiful visitor and America's smallest member of the Falcon family. I think it is wishful thiking that anything preys chiefly on House Sparrows,especially a tiny bird of prey like a kestrel. Insects and small mammals are what I've seen and read are their primary diet. Baby House Sparrows might be small enough for them to handle.

Nevertheless, you have a really good bird visiting and they will nest in a cavity, including a nest box. I think a 2" entrance is the correct size. I'm sure someone here will correct me if I am wrong.
They will need a nest box larger than a Bluebird house, ideally mounted high on a pole near a field.

Enjoy your visitor.

Rob Barron
Warrenton, Virginia

Joy,

Yes, you can set up a box for them. The hole will need to be bigger.

It would be nice if all they did eat was House Sparrows but they will eat the Bluebirds to.

When I was a kid they were called sparrow hawks.

Maynard Sumner
Flint, MI

Hi, Joy:

Rob is right ... American Kestrels primarily feed on larger insects ...
especially grasshoppers! If you would like to try to attract them with a nest box, your biggest challenge will be in getting it mounted high enough for them.

Most of my kestrel boxes are mounted at 15 feet and I have never had a pair use one of my boxes mounted lower than 12 feet. Obviously, monitoring at this height can get fairly precarious! Not just because of the height ... but also because at this height, bee swarms can be a major problem! (I would definitely be interested to hear from anyone that has ever had them nest at lower heights.)

Also, I use a 3-inch entrance hole ... with an 8x8 floor for my kestrel boxes. You will want to install it at a forest edge ... preferably facing fairly large, open fields. Depending on the quality of the habitat, a successful pair of American Kestrels can easily require a hunting territory of up to 250 acres.

I hope this helps ... and keep us posted if you snag a pair!

Take care,
David

I use "Purple Martin" house poles to reach 15'.
The ones I have are triangular aluminum and slide into each other,
allowing you to bring them down to 5'.
They have plastic sleeves that sometimes come with them or can be
purchased separately.
I dig a hole and embed the sleeve in concrete.
The entire pole assembly can be easily removed if necessary.
We currently have four in use although none for Kestrels.
We have seen them I the yard and they are beautiful birds.
Maybe we will try to place a nesting box next year.

Herb Kelley
East Central Missouri.

Thanks for the information. I have recently been experimenting with a
modified flag hoisting mechanism that has been outfitted with brackets
that attach to the box. This makes it much easier and safer for me, but
the Kestrels don't seem to like the on-going movement of the box.
However, I just keep trying!

Thanks again,
David

I monitor WODU boxes and they are mounted about 8 ft.
off of the ground. They are on 10 ft. metal poles
that are buried about 2 ft. We have had a Kestrel AMKE
nest every year for the last 3 years ( when they were
put up). The WODU boxes have the 3 x4 inch eliptical
entrance hole.

Vicki Butler
Sacramento, CA

From: Evelyn Cooper [mailto:emcooper"at"bayou.com]
Sent: Tuesday, May 16, 2006 6:42 AM
Subject: Re: my NEW friend!

For anyone who has not seen them, we have some beautiful pictures in our "Pictures" section of American Kestrels on our website by Don McCartney, OR. He raises them.

I enjoy my little fellow when he migrates every year to my place. I also see the Bluebirds sitting just a few feet from him on the power line. I feel he is more interested in something else than the Bluebirds for lunch or they would not be that close.

Evelyn
www.labayoubluebirdsociety.org

look at the top of the first page, you will see numbers. Click on #7 and that is the page the Kestrels are on.

Hi Joy,

How lucky you are to have a beautiful female kestrel in your backyard!

For many years I lived on a farm with a nesting pair. Several times the kestrels chose to nest in a hollow space between two walls of an old bank barn. I was thrilled to be able to observe the young birds develop through chinks in the wall of the barn's storage room. (This was in pre-web cam days).

Most years, I could watch the whole family (adults and usually two young
birds) out together flying and perching for a few weeks post-fledgling.

The kestrels regarded the farm as "theirs" and would scold me daily from their favorite perch in the top of an old wild cherry tree.

As other posters have pointed out, I am afraid you cannot rely on a kestrel to rid your backyard of HOSP. American Kestrels rarely take prey this large (about 75% of their diet consists of large insects).

The bottom of my bank barn was also the summer home of a colony of 20-25 nesting pairs of barn swallows. For time to time, I would see one of the kestrels capture a swallow (about 2/3 size of a HOSP). Barn swallows are my favorite birds, so I was always a bit sad when I witnessed this.

Last year, I moved to another farm about twenty miles to the north. Although I am surrounded by parkland with many wonderful birds, there are no kestrels here.

The state bird organization tells me that American Kestrels are rapidly declining from much of their former range here in. All the reasons are unclear, but the rapid loss of suitable habitat to development is considered a major factor.

It would be wonderful if you put up a kestrel box: this species probably needs help throughout the US.

Enjoy your kestrels,

Felicia

Sykesville, MD

From: Dean Sheldon [mailto:seedbed"at"accnorwalk.com]
Sent: Friday, February 16, 2007 9:40 PM
Subject: Fw: Fw: hanging Kestrel boxes

Dick Tuttle of Delaware, OH has done a great deal of experimental work on the placement of Kestrel boxes....especially relating to the use of heavy-duty highway sign posts for this prupose. His comments with regard to Vicki Butler's inquiry are given below. Dean Sheldon, Greenwich, OH

> Dean,
> I'll let you handle how to relay my answer since I don't know how
> the bluebird-l works.
>
> Kestrel boxes raised and lowered with poles, that is the question.
> I assume that the question concerns hanging a kestrel box like a gourd
> as it is done by some in California. The good news is that kestrels
> will nest on sign mounted boxes as close as 8-1/2 feet above the
> ground. Kestrels will nest in sign mounted boxes that twist in the
> wind. Also, they do not need to be micro monitored since, contrary to
> what many believe, starlings are not dominant over kestrels. Kestrels
> eat starlings.
> Ohio has many raccoons so I will not mount a kestrel box to a tree.
> However, in the vicinity of Hawk Mountain Sanctuary in Pennsylvania,
> many kestrel boxes are mounted to solitary large trees standing in
> fields and they are quite productive.
> The bad news is that kestrel boxes are very heavy compared to
> bluebird boxes. Assuming that a pole lifting method is made foolproof
> and safe for kestrel eggs and families riding up and down like a
> gondola at a ski-lift, my advise is to try the idea and share the
> results, whether or not the kestrels respond and do well or fail.
> Since cavity nesting birds lack a choice among cavities, the idea
> would most likely work, however unconventional it sounds.
>
> Good Luck to the kestrels,
>
> Dick Tuttle
> 311 West Central Ave.
> Delaware, OH 43015

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