Cooper's Hawks And Great Horned Owls Predating Fledglings

[Steve Kroenke]

Cooper?s Hawks And Great Horned Owls Predating Martin Fledglings

Both Cooper?s hawks and great horned owls are predating purple martin fledglings in my neighbor?s (Bob) colony and mine. The hawks attack or try to during the day and the owls come under the cover of darkness. Owls are capturing fledglings that roost on the exposed gourd crossbars or house porches. I estimate we are losing around 2 or 3 fledglings a day to the hawks and several at night to the owls. We will have around a 1000 fledglings produced from about 250 pairs of martins. The hawks started their attacks in early June and the first owl kill occurred on the night of June 18 or early morning of June 19. I believe our total losses from hawk and owl predation could be between 100 and 150 fledglings over about a 6 week period. This represents about a 10 % or more mortality rate from predators. Not a single adult martin, egg, nestling or fledgling has been destroyed by any starlings or house sparrows and these species are of little threat to our colonies at this time. Natural predators, including both resident and migratory Accipiter hawks and merlins and owls, are the main threats to martins in our colonies.

The fledglings are attacked several times a day by Cooper?s hawks at their family assembly sites in tree canopies or on utility lines. There is a pair of resident Cooper?s hawks and both are actively predating the many martin fledglings in our colonies. I believe the hawks? nest is located about a mile or two to the west of our colonies in a deep woodlot. I have seen both hawks carrying caught martin fledglings to this area recently. Also, the hawks? may have fledglings and they are feeding them martins. I am seeing several visits a day by the hawks and I can always thwart their attacks when they come high over and are preparing to dive down on a vulnerable fledgling sitting on a nearby utility line. Today, June 23, 2005, both male and female hawks made 6 visits between 7:00 am and 1:30 pm and I intercepted all of them. The hawks are terrified of me and will not make an attack as soon as I confront them in the middle of an open area between our colonies. However, if I let down my guard, then the hawks will sneak high over and sometimes dive down and grab a fledgling in our colonies. That happened the other day and I saw the female carrying a screaming fledgling to a nearby woodlot. The parent martins mobbed the hawks constantly, but it is a futile effort. The hawks ignore the adults and just continue looking for fledglings. Upon seeing one, the hawks fly toward it and usually score a kill in spite of the valiant efforts of the parents to distract the predator.

During this period in the martin breeding cycle, many fledglings are either being brought by their parents back to our colonies to roost in their nests or the older ones are returning on their own. I had as many as 200 fledglings roosting on my gourd crossbars on the night of June 18, but no more! Bob had many at his colony, too. I really don?t like this behavior because of their vulnerability to night hunting owls. In areas where there both barred and great horned owls are present, there is a good chance these predators will see numerous martins roosting in the open on gourd crossbars or house perches/porches. The martins are sitting ducks and the owls will exploit this easy food source as long as the fledglings roost in the open.

My first great horned owl attack occurred either the night of June 18 or early morning of June 19. I often hear these owls hooting in a nearby woodlot. My open Lone Star gourd racks had over 100 fledglings sitting on the bottom tiers. The youngsters were packed side by side. I checked on them at around 10:00 pm June 18 and they were OK. I checked them again at around 3:00 am June 19 and nearly all were gone. This clearly indicated an owl attack. The next morning there were only 5 or 6 fledglings, probably recent ones, that were still on the crossbars. The older fledgling had left in the darkness. I found the plucked feathers of a fledgling in my back yard.

Bob?s colony is also being attacked and we have found several owl kills in his front yard. When owls take a martin to the ground, they will eat nearly all the flesh and leave a pile of plucked feathers. Owls also lose feathers in these attacks and I found a number of them under Bob?s housing. I have attached a photo of a recent kill showing plucked martin feathers and a single great horned owl leg feather mixed in.

When martin fledglings roost in the open on exposed gourd crossbars or house perches/porches, there is little a landlord can legally do to stop owl predation. You can try to stay outside all night long, but that is no fun and I have tried that in the past. Many of the older fledglings will eventually stop this suicidal behavior after several owl attacks. But when you have a large colony with many fledglings, then there will be a staggered roosting process as new youngsters come in to sleep and some ultimately end up as owl prey. So the owls can predate martin fledglings over a long process though the availability of prey will significantly decline as the martins gradually leave the area or fewer younger fledglings return to roost.

When an owl grabs a fledgling during the darkness, the youngster emits a bloodcurdling death scream that is greatly amplified in the excellent acoustics of the night or early morning air. I used to leave my window open in my bedroom so I could rush outside the moment I heard the death rattle of a martin being killed by owls. It is a sound you will never forget and I would find myself shaking afterwards. This scream will cause many of the other older fledglings to flee for their lives into the darkness; also the owl may dislodge several fledglings from a crossbar when he grabs his prey. However, not all fledglings will depart and the recently fledged youngsters may just sit tight. They are so helpless in the darkness and the owl will come back later for those.

The owl may take the fledgling to the ground underneath the martin housing or a good distance away. If you have a large well mowed yard, you may start see piles of feathers located all over the area. These are the kill sites where the owl plucked his victim. As the owls continue to predate our roosting fledglings, our yards may become littered with martin feathers. Not a pleasant sight to see when you check your housing in the mornings.

Both Bob and I still have about a third of our martin pairs with nest bound young. Nearly all of these will be fledging in the next week or so and we will have a few pairs that will probably fledge their youngsters by mid-July. So there are still several weeks of more Cooper?s hawk and great horned owl attacks. This aspect of purple martineering can reduce the enjoyment of managing your martin colony. The key is the intensity of the attacks and how many martins are being predated. In our cases, the hawks ignore the parent martins and focus on the fledglings. While not pleasant, this is ?better? than having parent martins predated and nestlings left behind to starve. The owls so far have only gone for the roosting fledglings and have not attacked martins inside the gourds/house compartments. Again, this eliminates predation on the parent martins. Predation in our colonies is primarily impacting the martin fledglings.

The martin season will soon be over in our area of northwest Louisiana. I will present a comprehensive report on my new martin colony at the conclusion of the nesting season with relevant stats. Hoping everyone is having a great season.

Steve

[John Atteberry]

I hate to hear this sad story of what's going on at your 's and Bob's colony! I hope you and Bob don't get discourage on having a colony every year! Like you went thru in Florida! Well I think I would shoot a shotgun up in the air or in the ground when you see the hawks to try to scare them away or shoot in the woods when they go off in their too, but not to kill them! Maybe the same thing with the owls too except not with a shotgun, too early in the morning. HA! I don't know about the owls! But I think the hawks would be scared with shotgun noise! Well if you don't have snake promblems, you have hawk and owl promblems! I wish there was something we can do! But that's life! I still wonder how we have soo many martins after what they go thru! John!

[Steve Kroenke]

Hey John,

One of the major problems with large martin colonies is predation from both Accipiter hawks and owls. This large prey mass attracts such predators like honey attracts flies! Fortunately, our open colony sites are greatly minimizing successful hawk predation on the parent martins. However, very little can be done to reduce the attacks by determined and persistent Cooper?s hawks on the numerous martin fledglings in the area. These hawks are relentless and are ?visiting? over here daily. Just this morning at about 6:00 am the big female hawk tried to sneak into my colony, but I intercepted her and sent her packing. We will have to contend with the Cooper?s hawks until the final martins leave the area.

The great horned owls are only preying on the martin fledglings that are roosting on exposed gourd crossbars or house perches. This morning one of Bob?s perches on his T-14 is broken down and I found the plucked feathers of yet another martin fledgling nearby. Nothing legally can really stop this predation until the martin fledglings stop roosting in the open. The little martins are committing suicide with such behavior.

Though it does bother me, at least the predation is only impacting the martin fledglings and not the parent martins where it would be most devastating. Soon the season will be over and the Cooper?s hawks and great horned owls will just have to work harder find food.

We are not discouraged and plan to continue our large martin colonies next season. I will even be expanding mine to accommodate the huge martin population base that exists in this area. Of course, that means continue predation pressure, but my open colony site is helping tremendously in minimizing the success rate of Accipiters on the adult martins.

Just one interesting point?so far, not a single rat snake has been trapped in my netting! Now that is amazing, as Bob had trapped a number of these snakes last year and released them away from his colony site. Perhaps he temporarily cleaned them out! Hope so!

Hope all is well with your colony.

Steve

[abernathys]

Hey Steve--Gosh--I'm so sorry to hear about the attacks on yours and Bob's colonies. Sure was hoping you could have a season without loosing any PM's to predators. Have you thought about playing a radio around your colony at night? My blaring stereo still keeps our GHO out of the yard. Don't know if it would help since the owl already knows about the food it can find there. Luckily I have had only one fledging stay on the gourd rack one night and he made it. Sure wish there was something that could be done to stop the attacks. I wish you luck with the rest of your season.

Sandy

[Steve Kroenke]

Hey Sandy,

I may use my sound deterrent system for owls next season. It worked at my Tallahassee, Florida colony for three years. But I am not sure if it would still keep the owls away when there are hundreds of fledgling martins roosting in the open. Such a tempting target for great horned owls! However, there may be some auditory fright value in the loud music. I don?t have the system capability this first season in Louisiana, but I may try it in subsequent years.

Fewer fledglings are roosting in the open at our colonies now after the owl attacks though every night there are always some that do and several will meet the Grim Reaper during the darkness. The poor little martins just flee wildly into the night when the owls strike the groups of fledglings sitting closely together on the gourd crossbars or house perches. It was amazing to see so many fledglings lined up on my gourd crossbars to roost! The most I had was around 200. The great horned owls have ended that interesting martin roosting behavior.

I am glad the owls are staying away from your colony and the music is doing its job.

Good luck.

Steve

[Guest]

Steve.
you mentioned the hawks are afraid of you. How do you scare them away? the hawks in my yard don't listen to my screaming and waving of arms.
thanks
sharon

[Steve Kroenke]

Hey Sharon,

These are Cooper's hawks and they appear to be "deep woods" individuals, not the "city slicker" types I used to see in Tallahassee, Florida where I used to live! When the hawks began their slow approach high up, they easily see me standing in the middle of the yard. Just my presence will usually result in them turning away. But I also clap my hands loudly and run toward them. So far, this has worked everytime with these hawks and they immediately leave the area. I have actually intercepted the big female hawk when she was diving at a high rate of speed and trying to grab a fledgling martin off a utility line. When I ran toward her and clapped loudly, she must have nearly had a coronary! Perhaps she thought the clapping was a gunshot. She fled the area and didn't return back that day.

But other Cooper's hawks are "tamer" and not that afraid of humans. I was amazed at how tame these hawks were in Tallahassee and I could easily observe and approach them when they hunted near my office building. I watched them catch prey and even pluck it with me some 50 feet away.

Many hawks are becoming "urbanized" and are nesting in downtown areas. This includes Cooper's hawks.

Steve

[Guest]

Steve, I know the sound you are talking about when a predator has a martin in the night. I heard it one night when I was on my patio about 10:00. It is a sound you do not forget. This happened about 2 or 3 years ago, and I still remember it. It was one of neighbor's martins.

Good luck, Steve, with your martins the rest of the season.



Lanell

[Steve Kroenke]

Hey Lanell,

Unless one has heard the sound of an owl capturing a screaming martin under the cover of darkness, you can't really understand how it can impact a landlord. It greatly impacted me.

The great horned owls are continuing to predate martin fledglings at our colony sites and plucked martin feathers are beginning to spread to different parts of the yard. We are finding a number of "owl kills" and the owls are losing many feathers during these attacks, too. This morning I believe we found two more sites where martin fledglings were butchered last night or early this morning. Also, the owls may be taking some of the fledglings away from the colony sites and eating the youngsters in the nearby woodlots.

However, the Cooper's hawks have been reducing their visits near our colonies due to fewer martin fledglings in the area. I saw only two "unsuccessful" visits the other day by the male hawk. Many of the fledglings are now getting older and are better flyers. We still have about a quarter to a third of our martin pairs with nest bound young. So these youngsters will be vulnverable after fledging. Also the hawks may be hunting martin fledglings away from our colonies at the martins' family assembly sites.

In spite of the predation, our martin colonies have done well this season and we are pleased.

Steve

[Guest]

Steve, I read your post and it made me cry. It made me think back on the day that our precious Mr. Blue was taken and the noise that he made as he was plucked right outside of the gourd. It is a sound that I want to hear never ever again. I just feel for these precious little guys as they sit outside their gourds, ever so trusting... and I know that this is nature, but I still get sad. I think the effort that you put forth is outstanding, and again, I am proud to say you are a fellow, friend, fellow landlord of our precious martins

[Guest]

steve....
its been years since I have been reading the forum....dropped out for a while between about year 16 and 19 or trying for martins (just got my first pair this year).....but anyway....about 5 years ago there was a guy that had some type of net or guard over his gourd rack. I think his name was something like Chuck Adabe....thats not quite right.....would something like that idea be useful??
I know I am not current on what works. but wouldn't mind hearing about it.
sharon

[Guest]

Steve.
just saw photos of your site....overwhelming.....good for you!!!!

do the fledglings also roost on the t-14 porches?? will they be susceptible to owl attacks at night on the t-14 too??? if I took some of the perches on the t-14 down, would they sleep inside???

don't want anything to happen to my one batch of babies.

sharon

[Steve Kroenke]

Hey Holly,

Nature can be raw at times. It is a most difficult time for martin landlords when the martins they invited to their yards as guests are killed by predators. We treat these little birds as family and protect them the best we can. But they are wild creatures and still face all the perils that other birds must confront every day and night of their lives.

I remember your postings about Mr. Blue and the hawk attack that ended his life. I have seen that happen so many times in my martin colonies. But I still always get emotional about it and try to intervene the best I can.

Thank you for those kind comments. I know you care very much for the martins in your colony, too.

Steve

Hey Sharon,

First, congratulations on getting that pair of martins! There are still folks trying to get martins for longer periods of time!

You could create a wire cage or wire canopy to cover a gourd rack or house. This may keep owls from reaching the nest entrances. I believe there are instructions for creating such guards in the Forum Archives. However, since the fledglings are roosting in the open on the crossbars/house perches, the owls could probably see them through a cage and still attack by hanging on the wire. This action would most likely create panic for the fledglings and they would try to fly out. Also, external guards on a gourd rack/house sometimes make it more difficult for the fledglings to return to their nests and enter. The newly fledged youngsters already have a hard enough time getting back to their nests and the outside barriers tend to amplify this problem at times, particularly with gourds. This may lead to the youngsters roosting on the guards or any exposed perches/crossbars. All that said, the external guards probably protect the adult martins and nest bound young more than not having such barriers.

I would not remove your perches on the T-14. Fledglings tend to roost on the porches/perches when the houses are already well occupied and the occupants keep the fledglings out. This outside roosting behavior is probably more typical of large colonies where there are numerous fledglings coming back in the evenings. Also, down here in Dixie, it is HOT in June and July so roosting on the outside may be more comfortable, but MORE dangerous.

Your perches on the T-14 are attractive to martins as they like to sit around their housing and socialize and watch for danger. So I would keep your perches intact.

I hope those babies do well and fledge safely.

Steve

[Guest]

Steve.
hard to imagine someone else battleing sparrows and all the rest of it for 19 years trying to get martins..... good.....wildlife needs all the help it can get.
sharon