First failed season ever....

[blivet]

We've been landlords for over 30 years now, and just had the only season that completely failed. I am trying to determine why, and could use some thoughts:

We have four 12 cavity metal houses located on the fringe of a city park in the Dallas area. A normal season for us in recent years involves 10-12 active nests with typical brood sizes. We have never had problems with starlings, very few sparrows, and few predators. This year, in mid June, the season appeared to be fairly normal until mid June, when all the martins just left at once. We gave it a few weeks, and when we lowered the houses we found a total of 32 unhatched eggs spread out among 9 nests. There was also at least one brood of four that had hatched at a normal time, but the young appeared to abandon the nest (or were stolen) before fledging.

A local bird conservation group mentioned that many of the migrating birds died on their way north in the big Texas freeze event, but it seems we had plenty of nests and eggs... We know about the disease that impacted many bird feeders but haven't heard that martins were affected.

At this point we are at a loss. Any ideas would be appreciated.

Thanks,

Greg from Texas

[flyin-lowe]

First thought would be a rat snake. They can go in one night and wipe out a colony. There is not many things that would cause 10-12 pair of martins to leave active nests all at the same time.

[blivet]

Wouldn't a snake have eaten the eggs?

[C.C.Martins]

Man, sorry to hear that. Terrible loss. Something got them, and they abandoned. no signs of predation? No dead birds or feathers?
To have them leave with eggs too. Id guess a snake, concur with flyin lowe. If there's no signs of a racoon or owl, leaves one thing. If it was big enough to go after adults it wouldn't bother with eggs, just go cavity to cavity. May not take many either, imagine the snake eating the adult martins, must have been quite a squabble. Other birds would alarm but if it goes on night after night they would leave.
Iv been watching that disease, sounds to me like it was something in those cicadas, thus far we have been spared in the south. None of our northern friends have raised an alarm.
Sure wasn't the cold. Not this late.
Just my 2 cents, sorry about your colony.
Tom

[brent]

Could be. Had a snake take a Bluebird chick but leave it's sibling alone. The parents would not let that chick stay. They coaxed it out even with it being only 10 days old. The snake breached the pole guard and snake netting only to get tangled in the netting on it's way down. The birds did not return to the nest.
Brent

[blivet]

Good stuff- so far I am hearing about pole guards... what's the best kind for snakes?

I did see a Hawk attack one of the houses, chased it off but no reason to assume it stayed gone. Would a one-time attack scare off all the martins? We have had a hawk hit our bird feeder before, lost a Jay and a sparrow we know of.... a friend of ours lost a good sized koi carp as well. Is there a way to hawk-proof a house?

[brent]

Look up Kingston stovepipe baffle guard. Lots of posts on the forum about snake guards and baffle guards. Also information on owl and hawk guards. I forget but there is a person who wrote articles on all these predator guards. I think her first name is Kathy. Maybe other members could add information for you.
Brent

[C.C.Martins]

Brent nailed it. Its Kathy freeze, she has a lot of good info here: https://kathyfreeze.blogspot.com/2020/0 ... e-and.html

You can also try Chucks Purple martin page. He has some good ideas on snake guards; we have 4 of his snake guards we built, they are really very good.
http://www.chuckspurplemartinpage.com

you need both the baffle and a snake guard. The baffle will keep raccoons and climbing predators away, snake guards to catch snakes. Yes its to catch them, it won't deter them. They get tangled up in the netting. We call it snake netting but its bird netting.

We have snake netting below and above the baffle at our satellite and home sites. we had snakes as well. I used Kathys snake guard idea below the baffle, caught 3 in a few days.

[flyin-lowe]

A single hawk attack would not cause all the birds to leave at once. Usually any bother predator other than snakes will leave a sign. Footprints, wings, feathers, torn off doors etc.

[GFB]

My guess would be an owl or snake. My experience is an owl is drawn to the colony when they get noisy with hatchlings. If they do manage to catch a bird they fly up to the peak of a building or tree and usually leave evidence of feathers and bird pieces on the building and ground. They don't always return every night but they do return if they were successful. Also look for snake skin sheds around the area.