Nestbox Predator ID (Part 5)

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

From: Hall, Jenny [mailto:Jenny.Hall"at"Remmele.com]
Sent: Thursday, June 08, 2006 11:54 AM
Subject: HELP HELP HELP

I could really use some advise ASAP. I am not sure what to do next...It is so heartbreaking to see what these blue birds have to go through. Joe and Betty (BB's) were robbed of their first brood. Betty and Joe have built a new nest and the first egg was laid and I came home to find it on the ground below the nest with peck holes in it. I then made "spoolers" and we hung them on the house. Within the next four days four more eggs were laid.
Unfortunately I came home yesterday and all four pecked out and laying on the ground. I am at a loss as to what to do next...It is truly heartbreaking and I don't want to give up. I know I can beat these Hosp's I just need help in doing so. So next step is?
A) Do I remove the nest?
B) Do I put in a Van Ert Trap? If So when and how do I monitor it? Will it harm Betty?
Please Help Fast!!!!

Jenny,

Are you sure that is is House Sparrows doing the damage? There is a possibility that it could be House Wrens, too. They peck holes in the eggs and often drop them on the ground just below the nest box. There is good information on Wrens and using Wren guards at:http://www.sialis.org/wrens.htm
I have had to use the guards and they have helped a lot, if it is HOWRs

Mary Roen, River Falls, WI

Denise
Parkville, MD

See sialis.org for links to both sites that sell these traps. Actually the two sellers are on this list and they can help you. Both send their traps immediately and they work as well as they say they will.

Denise

This morning I noticed that the TRES with week-old nestlings were acting
strangely: there was a third adult swallow hovering around the nest.

Later this afternoon I checked my boxes. A few lining feathers were on the ground and the babies were GONE. They have simply vanished without a trace.

I guess that the third swallow was a neighbor that answered the parents'
distress calls.

I assume that this was a snake attack, not a HOSP attack. A stovepipe guard was installed but I noticed that the hole in the top of the hardware cloth was slightly larger than it should have been to fit snugly around the pipe.
I should have replaced it earlier.

Will the TRES be likely to nest again here this year? This is a paired box with an active EABL nest (2nd brood) 20' away.

Felicia

Sykesville, MD

Hi Felicia,

That stinks, but I think you're correct about a snake, or maybe a big, strong, gymnastic raccoon. I've had them outwit many a stovepipe baffle. If you're up for a night patrol, I'd grease the BB nest box pole and put a tin can or something you'll hear get knocked off the nest box in the night, and have a flashlight handy. Once you find the culprit, you can decide the appropriate action, but I wouldn't mess with a raccoon at night without a gun and I have the rabies shots to prove it isn't an intelligent course of action.

What is the height of your nest boxes and where are they located?

If it's a raccoon, it will be back tonight since they're feeding babies too. A snake might be full for a day or two. Either way, it stinks. They might re-nest, but I'd move the nest box to a different location and keep a close eye on the BB box.

Good luck and keep us posted.

Rob Barron

Sorry for your loss. TRES only nest once per season so I personally
don't think they will nest again.

Could the 3rd TRES be a bachelor TRES? If so it's possible he got the
babies thinking he would then be able to mate with the female. I had that
happen with a pair of Martins last year. Such is Nature.

Dottie, Hickory Hollow
Brown County, Indiana

Stovepipe baffles usually have a seam that lets snakes climb right up the
seam. There are pixs of a black snake climbing up a stovepipe baffle on
The Bluebird Box.

Dottie, Hickory Hollow
Brown County, Indiana

Sorry about the babies. I have a nest of 4 tree swallow eggs that seems to be abandoned or the miserable weather is keeping the parents away. I have lost one nest of 4 bluebirds to hypothermia and another nest of 4 bluebird eggs to a possible scare by the cat I mentioned earlier or a raccoon.
Something tried to climb over the baffle. The female is gone. The male is looking for another mate. The eggs were then attacked by a house wren, I believe. Two eggs were missing and one was punctured. I haven't had luck at all so far this summer.

Maria
Norton, MA

Usually, the nest is left undisturbed if a snake gets the babies. If a four legged climbing predator gets them, usually there is some of the nest pulled out of the hole and the nest is left messed up somewhat. Avian predators will pull some of the nest out with the babies.

You can always keep the pole greased and if a snake crosses it, you will see signs where it left grease on the pole climbing to the box.

A few people have found that snakes will climb the seams of stovepipe guards, but I've never had that problem. Also, I inspect the hardware cloth carefully to make sure there are no places large enough for a snake to get past.

Evelyn

We've had Bluebirds successfully nesting in two Bluebird boxes on our property for many years.

We've been watching a new nest with five eggs in it for a while.
Yesterday, when I went to check the nest I found the female Bluebird sitting on the nest dead with no head. The eggs were still in the nest and the female appeared to be in a normal nesting position. No sign of a struggle or violence.

1. Can someone tell me what happened

2. How can I prevent this from reoccurring? As a precautionary measure I spread a 2-inch wide band of Tanglefoot around the post supporting the Bluebird box - which we usually do yearly, but neglected to do this year.

3. I assume this is obvious. We left the nest and the eggs but I assume all is lost. While examining the box we were "buzzed" by another bird that I assume is the male Bluebird. Should we just clean out the box and discard the eggs?

Sadly,

Ken
In Western North Carolina near Asheville

Ken,

Not sure who got the momma but sounds like a snake possibly. Do you have a predator baffle on the pole? If not, I would suggest getting them. Do you have a face guard on the box: this is another piece of wood by the hole that is cut from a 2x4 or 2x6 piece of lumber to make it impossible for a raccoon or other animal to reach in and get the mother. Those are my thoughts and without the list knowing the type of box and the protection you have for it, it is difficult to say more. Please describe your boxes better

My condolences on the loss of your momma BB, I know that must be very sad and heartbreaking

Thanks
Denise

Ken,

What you have described sounds like a House Sparrow (HOSP) attack. A snake or other predator would have eaten all the eggs. HOSP routinely decapitate adult birds that they trap inside a box. I have seen this a number of times this season in various Tree Swallow (TRES) nests. HOSP beheads adult TRES and builds a nest on top of the carcass. I have captured all of these HOSP.

If you are willing to control HOSP, my suggestion would be to set a Van Ert inbox trap in the box to catch the culprit. I would carefully monitor it in case the male Eastern Bluebird (EABL) reenters the box. Emptying the box would be appropriate and hope that the male EABL finds a new mate.

Paula Z
Powell (Central) Ohio

Yes, and the snakes swallow the babies whole. You can see lumps in the snakes' bellies of the babies.

I hope you have a good predator guard such as the Ron Kingston stovepipe guard. Another is the cone guard that slips on the pole. They come in metal or plastic. You can buy them ready made or build it yourself. Instructions are at www.nabluebirdsociety.org on the "Fact Sheets" page.

You need to grease the pole (I use automotive grease) mainly for ants, but that will also tell you if something has crossed it such as a snake or another predator climbing toward the nestbox.

Evelyn

Ken, my bet was a reaching predator. If it could reach in but not pull the whole body out, it might manage to get enough of the head to protrude and get eaten off. Then, after giving up on extracting the body, it dropped down onto the nest and in this case, might just look like she never quit covering the eggs.

A predator guard would stop most ground predators but only deep boxes or over-sized roofs will stop an avian predator like owls, crows or blue jays from reaching in.

You do need to remove all of the contents of the box so that another female
can nest.

Kenny Kleinpeter
Baton Rouge, LA

2 1/4" wooden guards on the holes of shallow boxes works too. I am experiencing this on my trail this year with Starling predators. So far, it has solved my problem and the three boxes predated have their third nesting cycles in them.

P.S. I only suspect the Starlings. There are Crows by the hundreds in this area too. Whatever is doing it, the wooden guards over the holes have stopped it. I would say use steeper roofs, deeper boxes and wooden guards on the holes if your problem is severe!!!!

Evelyn

Keith Kridler Mt. Pleasant, Texas

Evelyn and others have given good tips but you might want to wash your stove pipe predator guards once a year and apply a coating of car wax and buff it smooth. If they begin to rust they should be taken down, lightly sanded and painted with a gloss or semi gloss enamel to keep them slick and make them look better. This is a good winter project.

Harry Krueger would take all of his pipe for mounting poles and sheet metal predator guards and his PVC pipe predator guards to a small local car body shop. They nearly all use two part epoxy or added hardener type paint and once mixed now needs to be used or dumped out of spray guns within a matter of hours. He found this paint man in the body shop that when he painted a green car he would use up the car paint left over on Harry's PVC guards. He used brown or black paint on the mounting poles ETC. Harry got a free paint job and the body shop got rid of "hazardous waste" and received a couple of nestboxes.

Good tips on checking to see if the wire in a Kingston stove pipe guard is secure. 1/2" mesh hardware cloth might let in a snake large enough to eat an egg or two or maybe a very young bird. But it would not be large enough to eat a full grown healthy bluebird as it would not be strong enough to bite it and then kill it by constriction as rat snakes coil around their prey and smother them very slowly. They hold pressure on the creature and every breath the prey lets out the constant pressure slowly will over power breathing muscles and it gets to the point the animal cannot take a deep enough breath often enough and will pass out and become a meal. I saw a rat snake catch a full grown squirrel in our back yard trees and it fell about 20 feet to the ground during the struggle. It was a LONG slow DEATH for the squirrel. Snakes swallow their prey whole. KK

Emily,

With trees in your area, you are probably in House Wren (HOWR) habitat?
Also, if you have HOSP in your area, either bird could have hauled the eggs off and left no sign. Sometimes they can carry them a ways, but often drop them at base of box. Did you find any broken eggs at the base of the box or near it? If so, it was likely one of these birds. Just something else to consider...

Paula Z
Powell (Central) Ohio

I have been looking at the NABS "Fact Sheets" for predator control. I am interested in avian control (other than HOSP) and really don't see anything that addresses that. It talks about HOSP control, but does not give any information and recommendations (at least that I could find) for larger birds getting your nestlings or eggs.

It has stopped recommended the 3/4" wooden block guard (recommended for cats and raccoons) because they could still reach past them. I found it ineffective for avian predators too. I tried two of the 3/4" wooden blocks and they still got past it. I added the third one and it is working.

The only recommendations I have seen have been to use deeper boxes and some say a larger overhanging front roof will help. (even though I did not read this on the NABS site recommended for avian predators, it was recommended for cats and coons) I think of the thousands and thousands of shallower boxes that are all over our nation and surely we can find a way to still use them. I have some brand new put up this season.

I really like the front top opening for the thicker wooden guard. On the bottom opening, my husband slanted the guard to where the door would open better.

I check on my three boxes that were affected this year, and as I have stated, so far this 2 1/4" wooden guard is working. The parents have no problem feeding the babies and the female has no problem going in and out to incubate.

If anyone else has read anymore information on this subject, I would be interested. I do know that the 6" or 8" long tube placed on the hole was said not to be accepted by the birds.

Maybe we should have some studies and recommendations for this problem.
Several have mentioned having larger birds predate their boxes this year.

Evelyn, Dehli LA

From: Kelley Family [mailto:herbsho"at"centurytel.net]
Sent: Wednesday, June 14, 2006 7:09 PM
Subject: Re: Nesting female killed!

Evelyn,

Thanks for clarifying your 2-1/4" wooden guard.
Last year I had a neighbor report seeing Blue Jays attacking BB nestlings on the ground under the BB nest box. I added a 1-1/2' wooden guard (2X4) and have not had a problem since. However that box had been up for three years
before the predation had occurred. So I cannot say with certainy that the
guard has solved the problem. I have also had one occurance of Wrens pulling out BB eggs. The single application of the wren guard is working so
far on that box. Four eggs in the nest with two wren nests nearby. We
spend a lot of time talking about ground source predators and with the
exception of HOSP we really do not address an avian threat. I agree with
you that we need to gather more information on avian predators and ways to
prevent their attacks. I am willing to help. How do we do this?.

Herb Kelley

Well, I don't have House Wren problems as they don't nest here. .

Maybe Bet and Keith (or anyone else) can give this some thought and help us
come up with something. If enough people that are having problems could use
the thicker guard and keep records, it could have credibility. If someone
else has any ideas, it could be tried also.

One thing I noticed, the female did build the nest a little higher on those
that have the wooden guards on them. After she laid her first egg, I took
some off the bottom to lower it.

Evelyn

I have a question for you all, a puzzle to me. My bluebird laid 5 eggs in March. They all fledged and then she laid 4 more shortly after. I checked the box several days later and all but one were gone. No evidence of the box being tampered with, no egg shells on the ground. My husband checked on it a few days later and he said there were no eggs in it. :o( I put a baffle on the box pole thinking that there was a snake getting in there. A few days later I checked the box and there were two eggs in there and today my husband checked it and the female was laying on the nest and when she flew off there were 5 eggs in it. Has anyone else seen this? We have another nest box that the sparrows have claimed. I just got my Van Ert trap and my husband has to install it. Well, the bluebirds were checking that box out today! I'm confused. Anyone else have something like this happen to them?
Denise Hunter
Cresson, TX

I agree with Keith and Kenny. Snakes all swallow their prey whole, constrictor or not. They have no incisors or molars to bite off anything.

Even a large bird of prey doesn't have the correct beak design to sever a head; theirs are designed for ripping off flesh or swallowing prey whole if small enough. A Golden Eagle could probably do it, but they could rip the front offthe box if they wanted to. No Blue-jay, starling, woodpecker or small owl can sever a Bluebird;s head cleanly.
House Sparrows can peck a head off, but it leave a messy gash.

Cats and raccoons usually sever the head, yank the entrails out,and then regurgitate the kidneys after swallowing everything else. They must instinctively know that an organ that filters out waste shouldn't be retained.

How high was the nest box? I'd put my money on a four legged predator.
I think bird on Bluebird predation is highly overestimated. I had a Cooper's hawk in my yard for months and it ignored the Bluebirds in favor of fat young Mourning Doves. Just my opinion. I'm no expert. A trail-cam would help solve this mystery but mine stopped working and nothing is bothering my nest boxes. I'm just really lucky.

Rob Barron
Warrenton,Virginia

My money is on a weasel. Weasels are known to enter chicken coops and behead every chicken in the coop, leaving the decapitated corpses behind.
They are small enough to stick their head in the hole, but I don't think they can get in far enough to get eggs or nestlings.

Linda Ruth
Coventry, CT

Denise,

I have seen this many times here in HOSP country. What has probably occurred is the HOSP removed the clutch and the female EABL has now laid another one. It could have been the HOSP in your other box. I believe that native cavity nesters are not safe when there are HOSP around and I actively control them as much as possible.

In a situation where HOSP have claimed a box, I carefully remove the nest and install my two mounting screws for the Van Ert trap. A short, stubby Phillip's head screwdriver is the only tool you need. Trap comes with a template, but I just place the trap in there and use it as a guide. Make sure it will adequately block hole when sprung and make sure your box vents are not too large (i.e. no alternate means of escape). If box vents are too large, I stuff a rag in them when I set the trap. Once I have trap set, I take top portion of HOSP nest and any eggs and replace them. It is important not to put entire nest in there (unless it is small start of a
nest) as the height of a completed HOSP nest will not allow trap to spring shut properly. Stick a strand of grass out hole and check for orange dot every half hour to hour at most. If it is sprung, you have almost certainly
captured one of your HOSP. Back off door closing hardware, but keep box
shut. Put mesh laundry bag over entire house, cinch tight and open up box.
You can grab HOSP through the mesh. Keep one hand on him at all times or
he will escape. I would reset trap immediately after catching one and get the mate - keep your EABL much safer. I leave any eggs and top part of nest in there until I catch them both and then remove everything. If you catch the male first, female may abandon nest, but not always. Both male and female are aggressive and dangerous to native cavity nesters.

Paula Z
Powell (Central) Ohio

Thanks Paula for your reply. Would there not be egg shell fragments on the ground if it were a HOSP? I haven't seen the HOSP for the past 2 days so I'm thinking maybe he knew I had a Van Ert trap? *smile* My husband was out there trying to shoot them with a pistol and all that did was teach them to fly away if they saw us. My husband even tried to sneak around the house but they flew off when they heard the garage door close. They are really smart, aren't they? They have a trashy nest in one of the boxes, the one the bluebirds were checking out yesterday. I checked the BB nest this morning and the 5 eggs are still there.

Denise
Cresson, TX

From: Shawn [mailto:shawnee4"at"charter.net]
Sent: Friday, June 16, 2006 5:53 PM
Subject: EABL nestlings vanished

Anyone have an idea what might have happened? There were 4 eggs. Last Thurs. I counted 3 hatchlings for sure (maybe 4, they were sleeping, and it is hard to tell). They are in a NABS style box with a Noel guard. My husband mounted it on a wooden post (which I wrapped with barbed wire from right under the box, down 3 feet). Today there is nothing in there. Surely a raccoon wouldn't be able to get be both barbed wire and Noel guard?

Thank you,

Shawn in Sevierville, TN

Was the nest messed up at all? Any additional nesting material in the nestbox? It could have been an avian, instead of a climbing predator.
House Sparrow, HOWR? Or is the box close enough to an overhanging branch, or a building, or another wooden post, where a climbing predator could have jumped onto it from above or from the side?

Cher

Hi,

Thanks for all the helpful responses re. our missing EABL eggs and the predator possibility. The good news is that the female is still alive; my husband snapped a photo of the pair checking out the (same) nestbox again yesterday! So, that was a relief. Since it looks like they may try again, hubby put smaller-holed hardware cloth on the top of the Kingston stovepipe guard and applied grease to the pole below it so he could see if a predator was climbing up. Our box is mounted plenty high, so I don't think any snake can get over the guard from the ground. Thanks again, and I'll keep you posted if they do nest again.

Emily
Efland, NC

Hello.... What's happening?.... A few days ago, 1 of my boxes( actually a neighbor's) had 3 EABL eggs there. It stayed as 3 eggs for a few days.
Then yesterday the nest had 2 eggs. Today there is 1 egg. Well, here are some explanations. A snake got in there each night or a HOWR has been removing 1 egg per day. I'm sort of discarding both of these, because I have a good baffle on the pole for the snake & snake problem usually is that the snake would have eaten all 3 eggs.
Right? What about HOWR? Also, every HOWR attack I've seen here for the last 8 or so years...all eggs would have been punctured & removed & thrown on the ground nearby. Didn't seen any of this evidence. The nest is perfectly still intact. So why has 1 egg being missing each day? Right now there is 1 egg. Will that one be missing when I check tomorrow? We'll see. Does anyone have any good reasons what's happening? One other thing, I have not seen the female around at all. So it's possible she had abandoned the nest earlier or was killed. Don't know. When I saw the 3 eggs, they felt somewhat lukewarm & at that time I was wondering whether she had started incubation or not. Wasn't sure. Anyway, let me know if anyone has had similar experiences.... Thanks....Horace in Durham, N.C. (Just thought of someting I should mention...the baffle might be somewhat too low on the pole. So if a snake did manage to climb over the baffle & get into the nest, why didn't it eat all the eggs? Why would it be eating 1 egg per night or day. Everything I've read says that it usually eats all the eggs. Right?

If the nest is undisturbed, it is probably snake. Rat snakes are good at it. They need not touch the post at all to get them.
Phil Berry
Gulf Breeze, Florida

From: Evelyn Cooper [mailto:emcooper"at"bayou.com]
Sent: Saturday, June 17, 2006 8:24 AM
Subject: Re: Messy Phoebes

On page 56 of "The Bluebird Monitor's Guide" it shows a long black rat snake climbing up the side of a vinyl siding house.

Evelyn

Keith Kridler Mt. Pleasant, Texas
I agree with Phil Berry that a snake probably got your baby birds. Unfortunately barbed wire is not sharp enough to deter four legged predators though either. Remember that most of these predators will enter the thorniest blackberry patch at night to eat their fill of this juicy fruit.

Noel Guards:There are all different lengths of these guards on the market. NORMALLY if a raccoon raids a nestbox with the Noel Guard (a rectangular tube about 3&1/2" wide by about 4" tall and about 6" deep made from hardware cloth wire) then you will find hair stuck in the edges of this wire where the raccoon leaned into the guard with one arm and felt around inside the nestbox and would pull out the baby birds one at a time and eat them on the spot, either on top of the nestbox roof or more often down on the ground near the base of the pole. They actually have a very long wrist and it is actually pretty simple for a raccoon to reach through a Noel Guard, into the box, bend their wrist and reach down 4" with their finger tips and remove the baby birds.

Normally the reason face guards and Noel Guards work at protecting a nest of eggs or baby birds is because in most areas it is rare for an experienced raccoon to raid your nestbox. The nestbox guards work because nothing really tried to get in! A vertical oval hole would also allow the raccoon to reach into the box and then down easier as these ovals are larger in square inches allowing a fatter arm better or deeper access into the box and the vertical height is 2&1/4 inches allowing a better downward angle on reaching to the bottom of a nestbox. Often the raccoon can reach into the entrance hole and I believe from their claws to their wrist bone is just over 4". There are larger and smaller coons out there in the wild.

Normally it is easier for raccoons to eat the corn from deer feeders, clean out a sunflower feeder or climb a fence and eat a bowl of cat or dog food. If they get hungry they will check out a nestbox on a pole as these look a lot like a sunflower feeder to them. These animals WILL eat a certain amount of food EVERY day or night! If they don't eat your wood duck eggs or your baby birds they ARE going to find something to eat. If you have too large of a population of raccoons or other predators in your area they should also be trapped and removed to balance predators to prey. KK

Thank you, Keith.

I didn't see any 'coon hair on the Noel guard. No feathers, either.

We may need to trap them and relocate them at this point. Still going to remove the wooden post and put a metal one instead, with a baffle and a Noel guard!

Thank you again!

Shawn in Sevierville, TN

From: Steve and Cindy Groene [mailto:hausgroene"at"comcast.net]
Sent: Tuesday, June 20, 2006 9:41 PM
Subject: Fledging and unhappy endings

My EABL fledged today! To recap, my male lost his mate last Thurs, 14 days after the chicks hatched. Today was day 19. I went out this afternoon to put out mealworms and noticed no activity going to the nestbox. Checked and they were gone. Took the nest out and cleaned out the box and left it open to dry out. The male was hanging around the rest of the afternoon and flying in to take mealworms for himself. Never saw any sign of the four fledglings.

I was out for dinner from 6pm to 9pm. Went out to put out a few mealworms and close the nestbox. The male dive bombed me at the nestbox and was calling loudly. I happened to look down and see a few blue downy feathers under the nestbox, which were not there this afternoon. I started looking around and saw more of them a little ways away. Followed the downy feathers and found a fledgling lying on the ground, seemingly untouched, under the TRES box which is 15’ from the bb box. I could not see where the downy feathers came off the body. It was not yet cold nor stiff. I looked around and picked up all the downy feathers I could. Interestingly, interspersed w/ the downy bb feathers were 3 female cardinal wing feathers. The male chirped at me the entire time I was out looking for and picking up feathers and the dead baby.

I removed the sparrow spooker from the nestbox. Is this what I am supposed to do in anticipation that the box may be used again this season?

Cindy Groene
South Lyon, MI

From: fitz
Sent: Tuesday, June 20, 2006 10:44 PM
Subject: Re: Fledging and unhappy endings

Cindy,
Sorry about the little bluebird. Sounds like a cat to me. Have you seen any cats around your yard, either feral or uncollared family cats? If so, it needs to be trapped and taken to animal control. Cats are so destructive to wild birds. Sounds like it killed the cardinal too. Cats will kill even when they're not hungry. Seems to me that a cat or a predatory bird like a hawk, crow or blue jay are some animals that would hunt prey in the open during the hot daylight hours, but only a cat would kill for sport and not eat the prey. A raccoon would probably stalk at night. A snake wouldn't have left a trail of feathers or a body.

If you have a small tree, shrub or bush close to aim the nestbox toward, the fledglings will have a safe place to fly to when they fledge, instead of jumping out of the box onto the ground. The other three babies could have made it to a tree and the male could still be feeding them even though you haven't seen him doing that. He will hear their calls and bring them food. A devoted male can feed the remaining 3 fledglings especially since you are helping him. The day of fledging seems to be a stressful time for the parent bluebirds. They "chit-chit" at me also.

You did the right thing to clean out the box and remove the sparrow spooker, however, a sparrow might very well try to claim that box now. If you have several house sparrows, you may need to buy a trap and eliminate them as I resigned myself to doing many years ago, for the good of our native cavity nesting birds.

Keep us informed if you see or hear any of the fledglings.

Carol
Your neighbor over in Oxford, Michigan

Hi Cindy,

The cardinal feathers are the weirdest thing I've ever heard, so I won't speculate.

Don't take this as criticism because I'm no expert, but I don't feed mealworms after the cold weather ends and insects are abundant. I've had fledglings disappear, and sometimes reappear, and sometimes not.
But, I've NEVER found a dead baby or parent in the nest box or near it, not in NY, Georgia, or Virginia.

I understand that I've been incredibly fortunate, and I'm relating experiences from backyard nest boxes that money wasn't a factor in constructing or mounting. But, believe it or not, once I started building oversized boxes with at least a 5"X 6" floor and at least an
8.5 inch drop from the center of the 1.5" entrance to the floor, and mounted no less than 6 feet off the ground, I have never lost an egg, baby or parent, not a single one.

Granted, these are "yard" nest boxes that were often easy to monitor from the living room, kitchen, or bedroom, but here in VA they've only gotten quick evening or early morning checks.

I guess I'm just incredibly lucky. BUT, it seems like I'm starting to see a pattern of a problem with feeding mealworms during nesting. Has anyone else noticed this?

Thanks,
Rob Barron

From: Bet Zimmerman [mailto:ezdz"at"charter.net]
Sent: Wednesday, June 21, 2006 9:43 AM
Subject: HOSP are not always the culprit

I think we have a tendency to put House Sparrows (HOSP) at the top of our list of usual suspects when missing/pecked eggs, dead nestlings or adults are found. Indeed, they are a very likely and common predator, and HOSP attacks occur far too often (and can be prevented with some effort – see http://www.sialis.org/hosp.htm for options.)

However, even though they are definitely a huge threat in many areas, they are not ALWAYS the guilty party. While I am in NO WAY trying to minimize the need to protect native birds from HOSP attacks!!, MANY OF THE METHODS USED TO PASSIVELY OR ACTIVELY CONTROL HOSP WILL HAVE NO IMPACT ON OTHER PREDATORS. For example if the culprit is a raccoon, you need something like a wobbly stovepipe baffle or nestbox roof with a big overhang (say 5”) to prevent future attacks. That’s why it’s so important to try to figure out what REALLY happened (which may be impossible sometimes.)

I agree with Kenny K that Ken's decapitated female was probably attacked by an owl or mammalian predator. The head was neatly severed at the neck - perhaps when the female was sticking its head out the hole to pant (for heat control) or to get ready to fly off or to be fed by its partner. Ken does have a Long-eared Owl family nesting nearby. HOSP generally peck the top of the head into a bloody mess. (see http://www.sialis.org/hospattacks.htm - WARNING - graphic photos.)

HOSP do peck eggs and remove them from the nest (usually dropping them right outside the nestbox entrance hole, with contents, which may be eaten later by ants etc.) Afterwards, they may or may not use the nestbox. People see a brown bird (http://www.sialis.org/otherbrownbirds.htm) near the box and assume it is a House Sparrow. However, House Wrens can also be a serious problem on the trail, especially later in the season. Sometimes House Wren peckage can be distinguished by two small (3mm or less) peck holes - see photo. http://www.sialis.org/wrens.htm. House wrens can also remove babies up to 4-5 days old. USUALLY their predation is followed by a stick pile up. Sparrow spookers are amazingly effective to deter HOSP – but they have no effect on House Wrens.

Typical signs of a HOSP attack are as follows:

- Adults or nestlings have visible evidence of pecking on the top of the head and in the eyes. Victims of an attack may be found dead inside the box. .
- Small nestlings may be removed from the box and found nearby, dead or dying.
- Eggs may be pecked in the nestbox (but usually not a pinhole like a House Wren piercing); or removed from the box, and found nearby or underneath it.
- HOSP may harass parents so they are unable to feed young, which then starve. They will be seen driving the parents from the box.
- Afterwards, if the HOSP elect to use the box (which does not always happen), they may be seen perching on top of it, or going in and out.
- HOSP may build their own nest on top of a corpse.

The list of non-HOSP potential predators/causes of problems in a nestbox is so long: ants, blackflies/gnats, blowflies, cats, fire ants, House Wrens, mice, nestbox design, pesticides, raccoons, rats, red squirrels, snakes, starlings, starvation, wasps, cold or hot weather, and woodpeckers. Also bear, bees, bluebirds, blue or scrub jays, chipmunks, cowbirds, crows or ravens, disease or internal parasites, feeding earthworms, flying squirrels, fox squirrels, grackles, gray squirrels, ground squirrels, hawks, honeybee, human vandals, magpies, mites, opossums, owls, intestinal parasites, skunks, Tree Swallow, violet-green swallows, weasels, west nile virus, window strikes and Yellow Jacket wasps. I've put a guide online with signs and solutions: http://www.sialis.org/predatorid.htm - input is always welcome!

It's almost a miracle that any birds survive such an onslaught.

Horace,

I think it is possible that a HOWR or HOSP removed the eggs. They are not always at the base of the box. They sometimes carry them a distance away.
Also, they may have dropped them near the box and then something ate them - all sorts of possibilities.

If snake could be culprit, don't discard possibility that he ate all the eggs and then the next morning, female began a new clutch and had 2 eggs in there. In the interim, the snake could have returned and eaten both of these eggs. The next day, she lays a third egg in the morning. You look in there and deduce that one egg has been taken when possibly two were taken the night before and this is the 3rd egg laid - can get confusing/interesting. She could be in the process of laying a second clutch which is getting eaten as she goes.

Some have also indicated that EABL can remove their own eggs if they feel they are nonviable? I have not personally seen this, but it is another possibility perhaps.

Paula Z
Powell (Central) Ohio

From: J [mailto:penet"at"myrealbox.com]
Sent: Sunday, July 09, 2006 6:26 PM
Subject: Yellow Shafted flickers in BB Box

Question for the list.
Some background first, I’m very new at trying to help the Eastern Bluebird population near my rural home in South Central Kansas. I joined NABS, read as much literature as I could find on the internet, then set-up two cedar nest boxes I purchased at a yard sale. One was much the better box that seemed to fit NABS recommendations; it had seven-inch depth and a 1.5 inch entry hole 1.5 inches thick. The other box I added a piece of cedar to make the opening 1.5 inches thick.

An Bluebird couple seemed interested in the better box the very next day after I put it up. However, a male HOSP continually chased them away, so I built one of the nestbox drop door traps and wound up trapping and disposing of three HOSP males before the Bluebirds had a chance to occupy the box. The BB’s built a nice four inch high nest and laid 4 blue eggs. They seemed likely to raise a family. Anyway, I left home for a three day period and when I returned I did not see the BBs I waited three days until I checked the box, the eggs were there, but the parents were nowhere to be found. I thought maybe a hawk might have killed the parents. I didn’t notice if the opening had been pecked or not. A week later I decided to clean out the box and found a one inch pile of twigs and no eggs in the box, the entry had been pecked out much larger. I watched early the next few mornings and saw a male and female Yellow-Shafted Flicker going in and out the box. What do I do now? I didn’t find anything to cover this on the internet.

A week later, more info you may not want know, I saw a male BB on a perch that was previously used often by the Bluebirds who laid the eggs.

Also, I forgot to mention earlier that I was so upset by the HOSP chasing the BBs away that I build another very effective sparrow trap, caught and drown 15 more HOSP, total of 18 less HOSP. Now the only HOSP in my neighborhood are a female with two recently hatched juveniles. I’m about ready to set the trap again.

I would appreciate help from any experienced Eastern Bluebird expert. What should I do? What did I do wrong?

Jim Penn
Hopkins Switch, Kansas

From: David Gwin [mailto:David.Gwin"at"cityofcarrollton.com]
Sent: Sunday, July 09, 2006 10:36 PM
Subject: Re: Yellow Shafted flickers in BB BoxHowdy, Jim:

Hmmm ... I haven't yet had your problem with Flickers ... but I have, on several occassions, had the problem with Red-Bellied Woodpeckers attempting to occupy my song bird-sized and designed boxes. You can protect against this by installing a slate or soft metal entrance hole guard on your boxes. This installation will also protect against squirrels.  FYI - If you elect to go with metal guards be very careful to remove any sharp edges around the finished opening.

I hope this helps.

Take care,
David
North Central Texas

P.S. - Since Flickers don't build tradional nests in their cavities, it sounds like you probably have at least one other species helping in this regard ... i.e. the owners of the sticks! House Wrens?

From: Keith & Sandy Kridler [mailto:txbluebirder"at"sbcglobal.net]
Sent: Tuesday, August 01, 2006 7:06 AM
Subject: Re: House Sparrow killed in Gilwood nestbox graphic discussion

Keith Kridler Mt. Pleasant, Texas
Starlings killing birds: I have worked around poultry and beef processing plants since the early 1970's and have watched the interactions of hundreds if not thousands of nesting starlings and house sparrows. Starlings will actually start feeding on the bodies of chickens that have been killed outside before the chickens have quit moving. I have watched numerous times as starlings have entered cavities in buildings and attacked nesting house sparrows. Without camera's inside these it is hard to tell if they are actually killing the competing birds or if they will only drive out the other birds. It is known that they kill large baby birds of other species and it would only take a single well placed blow to puncture the skull of another bird. One of the problems proving that starlings kill adult sparrows or say bluebirds is that these birds are VERY capable of pulling out full grown purple martins or bluebirds or sparrows from a nestbox and flying off with them. They routinely can and do remove Flickers from nestboxes, have been reported to drive out wood ducks and even kestrels have been said to abandon a nestbox under attack from Starlings.

Flying Squirrels, chipmunks, red squirrels,rats ETC. can all kill and eat smaller birds. Rodents sometimes only eat the brain of the adult bluebirds.
Mice sometimes only eat the legs and wings of newborn chicks. It is normally pretty hard to tell the difference between the bite of rodents and the damage done by a house sparrow. No crime scene is ever quite the same. If a rat or squirrel is sleeping in a nestbox and is jumped on by say a bluebird entering the nestbox the rodent may grasp and kill the bird with a bite to the neck and not ever take a single bit of meat from this bird. It killed the bird out of fear or defense of it's sleeping quarters rather than attacking because it was hungry. KK

From: Cher [mailto:bluelist"at"localnet.com]
Sent: Friday, August 25, 2006 2:07 PM
Subject: Re: New Member Intro (Christine)

Christine,

Welcome to the List. Never mind our end-of-season heated discussions. We all tend to get a little cranky once nesting season is over.

What an interesting account, and it certainly presents a mystery.

I'd guess that something had happened to the adults, but both at once?
And then, where did the eggshells go?

I'd guess at nest abandonment because of a wasp infestation, but again - why would the shells be gone if the adults truly abandoned the nest before all the eggs had finished hatching?

I'd say your rat snake found a way to get around your stovepipe baffle on the wooden post - but then why weren't the babies taken?

You say you wonder about your "presence" during the hatching - how close were you? There's a world of difference between watching from the house and (to use a hyperbolic scenario) standing on a stepstool in front of the nestbox to watch the hatching.

It seems your story generates more questions than answers.

Personally, I'd go ahead and get a new box up on a metal post now - any roosting done in the current setup would be subject to the same hazards the nestings fell victim to - whatever it was.

Cher

From: Duane Rice [mailto:drbirdsong4"at"hotmail.com]
Sent: Saturday, August 26, 2006 4:33 PM
Subject: Re: New Member Intro (Christine)

Christine,
First of all, Welcome. I hope you find as much of everything here as I have. I always look forward to seeing what has been said about whatever, between visits.
Second, I'm sorry that your first bluebird encounter was such a bummer. I try to tell people just getting started, to prepare for some dissapointment,but not to get discouraged and don't give up.
The good far outweighs the bad,& I don't just mean the birds. The people I have met, and the friends I have made through the world of bluebirds has made up for a lot of negative feelings about the state of the world we live.
In general, Bluebirders are positive, upbeat, and loving people, with a comPASSION for being good stewards in many ways. You sound as if you fit right in here.
As to the Whys: It's just a guess, but if you had a snake encounter once, you were probably visited more than once, when you weren't around. It had to be something frightening for the pair to abandon the box right as they were hatching. Snakes are very good at climbing just about any pole, and they leave a scent, so they can find their way back to a food source. I can't imagine why the snake didn't eat the hatchlings, maybe it got scared off by
something. You'll never know for sure. Which brings me to another point.
Being a landlord means you'll have many unanswered questions, as anyone here will tell you. However, you will learn so much more. Sometimes we can figure things out here, sometimes not. Just venting is all we need to do sometimes.
The great thing is to share your experince. By doing that, we all grow and learn to better landlords, and the bluebirds reap the benefit in the end.
Laus Deo!
DR

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