Dead Adult Bluebird (cause)

Also see Dead Nestlings and Dead Tree Swallows

In addition to Messages that have appeared in the Bluebird Mailing Lists on this topic, the following are on the Audubon Society of Omaha website:  Predators and Problems On The Bluebird Trail

Hello...Just the other day, I found a dead EABL in 1 of my boxes at the tell end of winter here in N. C. Don't think it had been in there too many days. Trying to figure out why. If it were later in the spring or summer, I could understand why... probably from a predator. That would have been more logical. But we are still in winter (although a mild one here in N. C.) I don't think it froze to death here, because it hasn't been really that cold..only the mid 20's ..maybe a little colder 1 time. If it were sick, it seems it would have probably fallen onto the ground & died...don't you think? I've found many dead birds on the ground over the years. Well anyway...what do you think is the most logical reason for this dead EABL being in that box this time of year. Anyone with a similar experience?
Thanks for any good logical explanations.....
Horace in N. C.

Hi Horace!

A weak bird will often die overnight while roosting in a box. It just can't afford all the energy to stay warm, which is why protected roosting sites are so important during the winter.

Anyways, did you feel the keel of the EABL? (That's the breastbone, just like on a chicken or turkey.) On a healthy bird, the keel is barely noticeable. A starving bird will have a very pronounced keel, since it's using muscle tissue to supply its energy needs.

The tail end of winter can often be the hardest for birds. Sure, it's warmer, but the food supplies are pretty picked over & the bugs aren't active yet.

Hope this helps, & i'm sure other people will have other ideas of what might have happened. Too bad we don't have a forensics unit. :-)

yours, Torrey

Torrey Moss
Kalamazoo Nature Center

Hi Torry...Thanks for your reply. Answering a couple things you mentioned...No I didn't feel its keel this time. Now that I know..next time I will. Addressing the starvation issue you mentioned.... if the box was somewhere else..I think I'd agree with you that it probably was starving.. but believe me Torry, I put out plenty food for bluebirds (& many others). Here is what I put out every morning....special suet(which I
made) containng peanut butter, plenty of Dogwood berries, sprinkles of corn bread on the ground, peanut chips, peanuts out of the shell (mainly for the birds that can chip away at them, other whole peanuts (that are not for the Bluebirds) plus the usual sunflower seed stuff. Every day I see the EABL eat the 1st 4 things I mentioned.
Have you also seen a dead EABL in any of your boxes in winter? I notice you're way up in Michigan where it gets plenty cold...Thanks again
for you information.... Horace in N. C.

Hello....I got this as 1 of my dead EABL replies.
I think it's a good explanation. Our EABL's don't start building a nest until about 1 to 1 1/2 weeks before April 1. Is it generally true with people's bad experiences with HOSP... that most of the time the HOSP kills the mother EABL when she's sitting on the nest? Phil did say he found
a dead EABL 3 weeks ago..... Horace in N. C.

--- mrtony8 <mrtony8"at"cox.net> wrote:

HOSP will kill them now anywhere in the country. they are already nesting.
it happens to me every year, before the season even starts. i picked a dead male out of a box three weeks ago.
Phil Berry

Linda Violett - Yorba Linda, Calif.

Horace, every fall and winter a couple of dead adult bluebirds will be found in my nestboxes.

Historically, my birding season doesn't start (eggs laid) until I have found at least two dead adult bluebirds over the fall/winter. Last week I found a
dead female in a box with roosting poop. At the time of death, she had
been in the process of molting a few primary feathers and some of the sheaths hadn't been removed. Perhaps she was too sick/weak for proper grooming. Bluebirds can die of old-age, disease, sickness, hunger and Wendell might say some die of broken hearts.

From: bookfanaticef-bluebird"at"yahoo.com [mailto:bookfanaticef-bluebird"at"yahoo.com]
Sent: Sunday, March 06, 2005 12:51 PM
Subject: Re: Dead Bluebird?

I have just been able to check my email for the first time in several days, and have just read all the interesting posts regarding dead bluebirds found in nest boxes. I was checking nest boxes a couple weeks ago, and I also found a dead bluebird (in a kestrel box). I agree with everyone who has sent around suggestions--it could have been any number of things, depending on the condition you found the bird in.

The female my group found was somewhat mummified--she was sitting on an old nest from last year (and yes, there was poop in the box), esssentially intact, but dried up...all her feathers were there, except for a bunch on her belly on lower breast, but they were in the box, so we assumed they just fell out after she died. We guess that she died within the past 3 months, during winter, when the air is much drier. If she had died over the summer, it is so hot and humid here, I would think the carcass would have been more decomposed and "gross"--as happened when we found 2 dead nestlings last year (a sad day, but it happens). It was hard to tell if she had suffered any trauma (as from a predator) because the remains were so old, and the soft tissues were gone, but we ruled out predation because otherwise we assume she would have been missing some tail and body contour feathers (if the attack had failed &! amp; she managed to get away, but later died of some wound), or the body would have been ripped apart or partially gone, or something like that if the attack had been successful.

Our first thought was that the she might have dies from being "egg-bound"--a condition that is well-known of in some cage birds, and does happen in wild birds too. Sometimes an egg becomes too large to pass through the female bird's oviduct and out through the cloaca, and becomes stuck. If it remains stuck, it will kill the bird, especially since the cloaca is also used to pass feces. But we saw no eggshell fragments in the box or apparent in her body cavity, so we don't think that's what happened. And again, that would have been summer to early fall, and it's unlikely the carcass would have become "mummified."

So that still leaves many possibilities. "Old age"--though we know ours was not quite 2 years old, because we had banded her in April 2003, and in April 2004 she had eggs in the kestrel box we found her body in--and I've read that the average lifespan of a bluebird is from 3-7 yrs.

Cold winter weather--while those of you up north might not consider our winter weather cold, it is for us, and so could be deadly for a bird that stays here all year (while I know some Eastern Bluebirds migrate, our populations here are usually stationary that I know of), and has not developed a tolerance for temperatures around freezing. That said, I think cold alone might not have killed the bird, since overall we've had a warm winter, and only a few bouts of weather near freezing, and at most one or two weeks slightly below freezing at night, and a bird's feather coat is well-designed for keeping birds warm in temps much lower than that.

But cold probably reduced the insect population significantly, and she may not have been eating well enough to survive a drop in temperature, even if it only lasted a few days--birds have high metabolisms, so they need to eat a lot just to maintain themselves normally, and even more in winter, when they're trying to stay warm. Of course, if you give birds food in winter, and they're eating it, then that might not be as big an issue, and starvation or starvation + cold is less likely to be the cause of death.

Furthermore, the cold fronts often come with rain and wind, so if she got water under the insulating layer of feathers and to her skin (either while foraging or while roosting), the cold and the wet could have been what killed her. The kestrel box ours was in faced away from the prevailing winds, but sits high in an open field, and we've had enough very windy days that rain could have still blown in if it shifted to another direction.

Fire ants might have been the culprit, but we saw no ant nests nearby, and we think that she would have been less intact if ants had gotten her--at least to the point where she would have been missing far more feathers, and reduced essentially to a disarticulated skeleton.

And a number of other things--disease, parasites, a virus, a failure of some critical internal organ, or a combination of any of the things that I mentioned above. It's really hard to say sometimes. You just have to look at all the evidence you can find, and become a detective. Even then, you may not be able to correctly determine cause of death, especially the longer ago the bird died (and so the less remaining evidence there is).

Good luck with your boxes, andhopefully you won't find more dead bluebirds.
Elizabeth Farley
Gainesville, FL

Keith Kridler Mt. Pleasant, Texas
Light rain and 47*F Tadpoles have hatched out by the thousands. Elm trees and maple trees with full seed heads now and wildflowers and ornamental trees in full bloom.

Longer hours of daylight have the birds busy building nests. I checked a couple of nestboxes in my yard that have not been checked in several months.
One has new Carolina Chickadee eggs in it another had a dead male bluebird.
I will go back and try to determine how dried up the bird is to determine if it is from months ago or recently killed or has recently died.

Others on the list answered your question very well but we all need to investigate these "crime scenes". This is another reason to carry a pair of gloves with you and zip lock baggies. If the bird seems to have died of natural causes then this probably means a disease or parasite killed the bird and although not mandatory it would be nice to sterilize the nestbox with a mild chlorine bleach solution just in case it is something contagious for birds! Wild birds do NOT die of old age without something overpowering one of their body systems.

Botulism and salmonella is spread by sick birds infecting bird baths or bird feeders. There are reports from Alaska to New York right now in the "news"
if you do a search on "birds dying" where 50>150 birds are found dead or dying in different areas.

Anyway place the dead bird into the zip lock baggie and then disinfect your gloves or putty knife. You can inspect the bird though the plastic bag and then dispose of it minimizing exposure to germs.

Now would be a GOOD time for someone to copy paste the instructions for dealing with Deer mouse or the White Footed mouse nests that nestbox owners will be finding on these first nestbox checks of the year! KK

From: Dottie, Hickory Hollow, Brown County, Indiana [mailto:yumyumkatts"at"voyager.net]
Sent: Friday, June 10, 2005 2:49 PM
Subject: Dead BB

I found a dead male BB in one of my boxes. Couldn't find any injuries or anything unusual.

Dottie, Hickory Hollow
Brown County, Indiana

Today I found another dead male BB in the same nest box I found the first
dead male BB about three weeks or so ago. This one looked like he could
have been a juvenile. There is nothing in the box but the dead BB. I
didn't see any damage to the birds.

If we were not out in the sticks with our neighbors not close to us, I would think a human had did the deed.

Anyway, this is all too strange. Any ideas on what could have happened?

Dottie, Hickory Hollow
Brown County, Indiana

Keith Kridler Mt. Pleasant, Texas
Most birds do not die of natural causes because when they get sick or lose some of their ability to see or hear they will be picked off by a predator.
A bluebird lived in captivity till it was 14 years old. Bird banders who have banded thousands of bluebirds seldom if ever see a wild bird that is 9 years old. Most dead bluebird band returns are old at 4>6 years so most die in their early prime years!

Whenever I find an adult dead bird in a nestbox I assume they have died of some sort of illness if they have no damage to their plumage. Turn them over and see if feces are matted around their vent this would indicate some sort of digestive tract problem.

Female birds can become "egg bound" that is where the egg has formed with hard calcium in their oviduct then a sharp blow to the body that normally would not be fatal, batted by a cat or coon, flying into slow moving car or window of a building, picked up roughly by a person or a predator, could put enough pressure on the female to cause the egg to break. The broken shells are like really bad kidney stones and cannot pass through the female and she will get sick, infection sets in and she will die within a week. Of course male bluebirds and juvenile birds would not die of this:-))

We are in EXTREME drought in nearly all of East Texas with high temperatures everyday into the 100's. Last week I found birds bathing and drinking where water puddles at the end of our leach field from our septic tank. I had to add another 100 feet to the end of the line to keep it sanitary for the birds! Texas requires a "Clear water" system now for new residential sewer systems. The water is pumped out of sprinkler heads on your lawn or field now and if you don't add chlorine to your system the birds will bath in untreated sewage water every time the pump empties the tank. (thousands of humans eat vegetables everyday that have been irrigated with stream water contaminated with sewage, a few will get sick from the organisms, fewer still will die, same goes for other wildlife.)

In MANY parts of the country floods are also washing sewage and over flowing livestock manure lagoons, washing out chemicals in industrial holding ponds into streams and lakes creating pollution that is possibly deadly to certain individuals in any species. (Miami is having to dump raw sewage into vast flood plains this week.)

During nesting season bluebirds "normally" stay within a mile of their nestbox. Purple Martins and other swallows can feed and drink thirty miles away and be back in an hour round trip. Starlings will feed more than a mile from their nest site. California and Andean Condors will fly 150 to 300 miles each day from their nest site. Each species will drink and bathe and feed in all sorts of locations and be exposed to all sorts of chemicals and natural hazardous organisms and be attacked by numerous predators!

According to the U.S. Department of Justice on average 16,000 people are murdered in the USA every year.(Emergency room doctors save 4 times that many critically wounded.) Crime Scene Investigators CSI can normally track the victims every movement for their last few weeks and talk to family and friends and rely on autopsies. On average only 1,600 of these murders ever end up with a single conviction and only 160 end up per year with someone being executed for the crime. I expect that the best we can do when we find a dead bird is to bury it where it won't be able to spread disease to other creatures if we cannot determine the "cause of death." KK

I, too, just found a dead EABL Wed.! I believe he was one of the 5 babies that fledged about 5 weeks ago! I found him under one of my hosta plants.
My husband and I buried him and when we picked him up he didn't look like he had been messed with. A few days before finding him I had noticed one of the youngins' sitting in my maple tree for the longest time, kinda fluffed up, like he didn't feel too good. I'm hoping that he was just sick. I can accept that reason for death alot better then some of the others. I was wondering if it could have been West Nile. Since he was so young, could it have gotten him that quick? I also have found two dead house finches in our backyard about a month and a half ago. I wonder too if it could be chemicals someone to using in their yard? Not us tho. We do not use anything like that. Even if the bugs are eating my flowers, I let it go.
So, anyways, I hope these deaths are isolated situations! This is the first causality I have had with the EABL since I have had them nesting in my yard (3rd season), that I know about, anyways.

You all stay cool out there today (95 degrees here, yuck). And have a Glorious weekend.

Cristy
Lenexa, KS

From: Fultons [mailto:thefultons"at"everestkc.net]
Sent: Saturday, June 25, 2005 10:32 PM
Subject: Dead BB Mystery #2

I replied to an email Friday a.m. from Dottie, with the subject "Dead BB Mystery". Explaining that I, too, had found a deceased 5-6 week old EABL in my yard. I was accepting the find pretty well, hoping that he/she had been sick. But...I just found another 5-6 week old fledging EABL under some bushes in the front yard! Now I'm concerned. Neither one of them looked to have been messed with at all! It has been fairly warm, but not too hot, I don't think, to have caused it. What could it be? Could someone around be putting chemicals out and the babies are eating bugs that have been exposed? I had been putting chopped up seedless red grapes out for the robins and house finches and have noticed the EABL eating them. Could that be it? I also put out mealworms. Could it be West Nile? I'm scared I'm going to find more. I had 5 when they left the nest and I saw two babies on Thur. and none since then. And there are 5 more that should be leaving within the next week or so.

Anyways, thanks for reading. I know you all can't know for sure what is going on, I just thought I would share my tragedy with people who understand how I'm feeling. My heart is broken.

cristy fulton
lenexa, kansas

PS OT-I also have a snowbird/junco hanging around!! Shouldn't they have left along time ago? We only usually have them around in the winter. I saw him today and he is missing his tail feathers and doesn't seem to fly to well. I watched him for awhile and he seems to be bobbing his head up and down every few minutes. West Nile? I did see him drink some water and eat some seed from under the finch feeder. Also the Coopers hawk has been visiting quite frequently. I usually don't see much of them until the winter. He did take out a bird today in my yard and I seriously think it was a male HOSP. I really don't think he is the culprit regarding the EABL cuz nothing had been messed with when I found them.

From: JBrindo"at"aol.com [mailto:JBrindo"at"aol.com]
Sent: Sunday, June 26, 2005 7:53 AM
Subject: Re: Dead BB Mystery #2

Hi Cristy, With your hands in gloves, I would place any dead BB in a plastic bag and get it off to the appropriate person at Cornell Univ. as quickly as possible. Do this with all info on where and how you found it. They'll be able to analyze it for what may have caused it's death. You probable can email them to find out what department to address it to.
Jay Brindo
Mountain Glen Farm Trail
Northeastern Ohio

In my case, I think my BB baby was just weak and not yet developed enough to
fly like his brothers and sisters. Maybe because he didn't get as much to
eat as the others or maybe just a runt. ??

I don't know if my BB baby made it or not. I looked around but couldn't find him but they do blend right in to the edge of the forest and lay still when you come upon them.

However, if I find another dead BB in my box, I'm going to call DNR.

DNR just dropped in to say "Hi" to my husband yesterday while they were
looking for a deer poacher. My husband has been working part-time this
summer at the Brown County State Park so he knows several of the DNR guys.
They have a lot of authority around here.

We did have a Birder on BB L last year (I think) who found five dead BB
babies in her box. Her first and only BB babies. Come to find out, her
husband had put out grub control without her knowledge and her BB babies died because they were fed the grubs.

Dottie, Hickory Hollow
Brown County, Indiana

Before West Nile arrived in the States, the Kalamazoo Nature Center was assisting in tracking Eastern Equine Encephalitis (or EEE). During our breeding season banding, blood samples were drawn from the larger birds (like Gray Catbirds & Song Sparrows) & sent off to the lab.

EEE is generally fatal to hatch-year birds, the ones that just fledged this season. After-hatch-year birds, the adults, can handle the infection. EEE can also be fatal to horses & people. (There's a vaccine for horses.) There are other strains of equine encephalitis, too.

Other ways to monitor for EEE are to use captive birds as sentinels (you check their blood samples
periodically) or to catch & analyze mosquitoes.

West Nile might be the new & exciting disease, but there's lots of other stuff out there that's equally uncool for the birds. We just never hear about those diseases because they're old & they're not as dangerous to people.

(We still collect blood samples, & i know they're tested for WNV & i think for EEE also. I've been nest searching the past couple of summers & am kinda out of the loop of summer banding.)

Torrey Moss
Kalamazoo Nature Center
Kalamazoo, MI

From: Fultons [mailto:thefultons"at"everestkc.net]
Sent: Saturday, September 03, 2005 11:32 AM
Subject: My heart is broken

I woke up this morning and found alot of feathers on my driveway by the garage and they have blue on them! I know that it is nature and the hawk has to eat too, but...why must they go after the not so populated birds? Sorry to fill the list with my sob story. Just had to tell some one that can understand how I'm feeling.

Thanks
Cristy
Lenexa, KS

From: John Schuster [mailto:wildwingco"at"earthlink.net]
Sent: Saturday, September 03, 2005 12:01 PM
Subject: Re: My heart is broken

Dear Cristy,

Sorry about the lose and I get a little chocked up when I loose a Bluebird or a Barn Owl to a predator too.

However, though Hawks and Great Horned Owls need to eat, you need to remember that we can only do what we can do, so the rest is up to mother nature and survival of the fittest.

Like my friend Steve Simmons and I like to say about Barn Owls that get picked off by Great Horned Owls and I'll quote;

"Any Barn Owl that get picked off by a Great Horned Owl doesn't deserve to be in the gene pool." These are the hard facts of life, but true.

If you think of your above Bluebird lose in that way, then the Bluebirds that watched (Bluebirds are very observant) the killing and survived will become better equipped to avoid such attacks in the future, thus improving the gene pool for future Bluebird generations to follow.

...

John Schuster

From: RBALTRUNAS"at"cs.com [mailto:RBALTRUNAS"at"cs.com]
Sent: Saturday, September 03, 2005 2:06 PM
Subject: Re: My heart is broken

Hi Cristy,

Death is something we wish didn't have to happen. Two comments about it:

1. If all the EABL who were born went on and on having 2,3, 4 and even 5 broods each year who did the same then the world would soon be overwhelmed with EABL overpopulating the food available to them. So the process of life and death is part of a balanced environment.

2. Nature has a merciful way with older animals and birds. They die quickly from predation instead of the terrible dragged out deaths humans can be subjected to. They are lucky.

So maybe yours was an older one making room for a newer one. Be joyful for the new one!

Ron
Brooksville, FL

From: Dottie [mailto:yumyumkatts"at"voyager.net]
Sent: Wednesday, March 28, 2007 11:01 AM
Subject: FW: gourd birdhouse experiment

...

Sad news keeps coming in from BB'ers in our BB Club that they are finding many dead BB's in their boxes due to our wicked ice storm.

I'm hoping the four dead BB's I found in one of my boxes won't hurt my
numbers this year. So far I have a full BB nest and possible two partial
BB nests. This is early for me as I don't usually have a BB nest until
April.

Dottie, Hickory Hollow
Brown County, Indiana

From: Duane Rice [mailto:drbirdsong4"at"hotmail.com]
Sent: Wednesday, March 28, 2007 5:49 PM
Subject: RE: FW: gourd birdhouse experiment

Dottie,
...
I too found more dead BB's in my boxes this year than ever before.
Other the other hand, lots of nest building going on and I have eggs in three boxes.
Bluebirds Abound!
DR

From: Paula Ziebarth [mailto:paulaz"at"columbus.rr.com]
Sent: Wednesday, March 28, 2007 9:31 AM
Subject: Feeding Bluebirds

I monitor a number of trails and also do backyard Bluebirding. I feed nothing to EABL on the trails, but do feed my overwintering EABL diligently and give them a few mealworm treats during nesting season.

I think winter feeding saved some lives this winter because I have had other trail monitors in the area tell me about all the dead EABL's (one monitor found 65) that were discovered in their boxes during their first spring box check. It seems that the boxes with dead EABL's are in more isolated, rural areas where natural food sources were the only food available during the snow and ice that we had for an extended period this winter. I think the unavailability of natural food sources in bad weather is a very dangerous thing.

My boxes are in suburban areas and I believe that bird feeders have helped them survive this rough winter. I have found no dead EABL in my boxes this spring. I feed Bluebird Banquet during winter months, but I have also observed them eating sunflower seeds which are readily available at most backyard birdfeeding stations.

I believe feeding birds during winter in colder climates can save lives,
especially with the recent change in migratory behavior. Due to global
warming and generally warmer winters (not this one), many birds stay farther north than they did in years past and get hit hard when the unexpected bad weather comes in for an extended period.

...

Paula Z
Powell (Central) Ohio

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