Low temps that they can surivive

[flyin-lowe]

I'm asking strictly about the temp itself killing the birds, not lack of food or other factors. We have had temps in the 60's and 70's the last couple of days so they have been able to feed. Today it is high 40's and sunny and they are out feeding so I am not worried about starvation, however temps are forecasted to get into the mid to low 20's over night tonight and tomorrow night. Temps will recover during the day.....

Is there any documentation as to what temps martins can tolerate assuming they are normally healthy and well fed?

[randyM]

I'm not aware of any documented minimum low ambient temperature readings that will cause the death of a healthy martin. I would suspect a martin that was able to get adequate food during daylight hours could survive a night or two of down to sub-zero temperatures if they had protection from wind/elements in a nesting compartment. Birds having comparably smaller body mass than martins (chickadees, nuthatches, redpolls, snow buntings, house sparrows, etc.) endure extreme winter temperatures (-30-40F) in northern US/Canada, most without using man-made shelter. Such birds may have more down feathers and the ability to self-regulate their body temps during such extreme conditions than do martins. However, all birds have the ability to "fluff out" their feathers to trap a thicker layer of air next to their body to help insulate from cold temps and reduce loss of body heat, so I believe any well-fed martin will be able to easily survive a night of 20 degree F temperatures. In early Oct. in ND during past years I've seen barn swallows sunning and preening themselves the morning after overnight lows in the teens and they seemed to be just fine. I'm sure they took shelter in a nearby out-building the previous night to avoid direct exposure to the cold, but I'd venture to guess temps in surrounding non-insulated outbuildings with open doors/windows would have been well below freezing the prior night. Perhaps you could close most of your housing and keep a few compartments open and put hand warmers in those compartments for added peace of mind (or put warmers in compartments currently known to be used by your martins).

Randy

[PMDavid]

Hey there Lowe. For my 2cents also....... I’m with randy on his opinion. Your birds have been feeding well and they have somewhere to escape direct elements. In times of really cold they will bundle together several in the same gourd,etc....for warmth. I witnessed that here in the south during our recent terrible freeze . The four birds I had at the time all huddled in a south facing gourd. That was how I caught and saved the female. What killed all the birds here was the duration of the cold preventing any feeding for 5-8 days and then the brutal cold every night. A night of temps like you are saying on well fed birds and recovered temps in the day I share Randy’s opinion and say they’ll be fine. Best wishes for this season to ya.
David

[flyin-lowe]

I'm not overly worried about my birds, as much as I am just curious to learn. I am guessing they won't roost together just because it is going to be close to 50 during the day and as it gets dark then it is supposed to drop into the 20's over night (now it is moved back to tomorrow not tonight). So I'm assuming they won't see it coming. Plus on nights like this it usually only hits the low early in the morning then starts warming up with the sunrise. If it was going to be 20 degrees for 15-20 hours that would be a little different. I am curious if there is a temp that we know they start to perish.

[deancamp]

Doug Martin mentioned his early bird survived temperature at night well into the teens. I would think it would be different for every individual bird depending on it's overall health, age, body fat, etc..

[John Barrow]

Purple martins can survive extremely low temperatures. In the Texas freeze we had 5 days of continuous sub-freezing-non feeding- temperatures as low as 15 degrees. Martins can survive those temps. What they can't survive is loss of food and degradation of their body mass. We were supplemental feeding, but low on insects (nearly 2000). On the 3rd or 4th day a female launched out of a gourd and tried to fly. She fluttered right to the ground. We picked her up and brought her inside, immediately weighing her at 36 grams ( a normal weight is around 50-55 grams). That same day another female tried to fly and also fell to the ground below the racks. We brought her in and she weighed 33 grams. At that point we knew we had to bring the others in or they would die that night. All were communal roosting in one gourd. There were eleven martins in it, with one already dead. We pulled down the gourd and brought it inside and weighed each martin and separated them into three groups by weight and probable release status by weight. Over the next four days we fed each martin every two daytime hours (eggs and a cricket mix and meal worms we could acquire). More importantly, we weighed each martin after each feeding, releasing each as it attained a weight of 45 or more grams. All 10 of those survived the release and could fly fine. We know some stayed at our housing; we suspect others left.

We learned, doing some of the first geolocator studies we conducted, that handling martins without young would cause them to abandon a colony; even some of those with eggs. We are grateful some of the martins handled during the freeze feeding went right back to claim cavities on our system while others did not. We also know, living on a migratory flyway, that some of the 10 were migrating through when the cold freeze hit our area. That event was a lesson in the martin's endurance in extreme cold and the importance of having supplemental food sources on hand along with an adequate weighing mechanism. Access to a good rehab facility would be preferable, if available.

[flyin-lowe]

Thanks for the info John. I am curious what method you guys used to "house" the birds while they were inside. Also curious how you handled/fed them inside the house. I am assuming some type of box or tub but wandered how they acted and how you kept them from trying to fly around inside. I hopefully won't ever have to bring wild birds inside. I did have a rehabber tell me one time to never put a wild bird into a cage because they will for sure injure themselves.....