Though the season here is done and I suspect our South Florida roosts are also done, up in North Carolina things are heating up. The William B. Umstead Bridge in Manns Harbor plays host to a huge purple martin premigratory roost. The Manns Harbor roost is swarming with martins at dusk. For about another month or two these birds will be roosting under the bridge in such large numbers that warning lights were installed to slow traffic as hundreds of birds were being struck and killed by cars at dawn and dusk.

As years past the Coastal Carolina Purple Martin Society (CCPMS) will be having boat tours and for $30 a person you will be witness to a spectacle of nature. You can read about the tour on a previous blog post from last year or go straight to their website to contact for reservations at Purple Martin Roost Boat Tour Information.

Know of a roost near you? Make sure you visit it before they are gone.

(c) 2011 S.Halpin PurpleMartins-R-Us

Every season seems to end the same for me, here in South Florida. The end of martin season coincides with the start of our rainy season. Each morning our colony would get a faithful dozen or so visitors that would sit on the housing and chatter at any remaining nests. Late in the morning they would leave to only to return again the next morning. But then when a few days of poor/rainy weather persists, they are gone. I wrote a post last year about how it is thought that birds are sensitive to changes in barometric pressures and the weather , could avoid bad weather by delaying migration to an area of poor weather or vice versa. I’ll repost it here:

According to Melvin L. Kreithen and William T. Keeton of the Division of Biological Sciences, Langmuir Laboratory, Cornell University in Ithaca, New York,(23 October 1973) Homing pigeons were able to to detect air pressure changes. As purple martin landlords can tell you, a purple martins homing ability is at the very least equal to that of a homing pigeon. So the correlation is fair.

By any account, my season is over here in South Florida and all martins have left.

The factors that affect a birds migration are complex and not completely understood. Click this article for Neotropical Migratory Bird Basics from the Smithsonian National Zoological Park. If you want to learn more about Neotropical Migratory Birds read this article on Birds Built-in Barometer.

Not that my birds need bad weather to end their party, migratory birds know when it is time to go based on known factors such as the length of day and for some types of birds, even star patterns. There is nothing to be done for purple martins (or any other migratory bird-for that matter) that linger on. Some folks will tell you to lower or remove housing, but don’t bother. Just like the old wives tales that persist that tell hummingbird aficionados to remove hummingbird feeders to push hummers to migrate, nothing needs to be done.

So keep the feeders full, leave the housing up till you feel like it. Birds have been migrating for a long time and the only thing we need to do for them is support them, by way of a beak full of nectar, a belly full of seed or perhaps a dry place to sleep at night.

Our last blog post touched on one of the reasons that purple martin nestlings jump prematurely out of their nests. Referred to as “jumpers” these youngsters are often doomed. The reason why I,  along with many other South Florida landlords, have seen a huge increase in jumpers this year over previous is our record breaking drought conditions. Dry weather means fewer bugs which means purple martins go hungry and nesting success plummets.

The main reasons that martin landlords encounter jumpers are: parasites, extreme heat and hunger. Drought, though not a specific reason, contributes to low food supply and hunger/malnourishment.

Parasites can torment young inside a nest. Though some have argued that nature should be allowed to take its course, the natural instinct of the Purple Martin (Progne subis, subspecies: subis) has been altered by man.  Before Native Americans created the tradition shift in martins, the nest sites of these birds were tree snags and they nested farther apart. You can read about some of the history of martins at our parent site: PurpleMartins-R-Us.com. They were much like their West coast cousins, Progne subis, subspecies: hesperia and subspecies: arbicola. The shift not only affected were they nested (tree snags vs man made houses) but the way they nested, as it is believed they were not as colonial in their nesting. That is to say, they were spaced further apart and did not nest in such large groups. The groups of martins nesting in close proximity can create parasite population explosion. We counter this by periodic nest changes and/or the use of a small amount of Sevin. We have a great link to a video on how to do a nest change.

Extreme heat in a nest can  be challenging to combat but if not associated with drought or food shortages, are usually easy to remediate. By making sure all vents are open in nest compartments and gourds, air circulation can be increased which can help lower temps. Many artificial gourds have vents that can opened as an option. For example Troyer gourds have built in mini vent canopies that can be drilled open easily. We recommend drilling these open before the season but a cordless drill can open those up quickly. If those are too small or you want larger vents (more air circulation) than a 1/4 inch threaded PVC elbow (90 degrees) is perfect for the job. It can  be easily installed on any gourd or house for that matter to increase air flow. Just drill a hole large enough to thread the end in and caulk in place. Make sure it points down and, if you want, attach a small piece of screen to cover the opening to allow air in but keep wasps out. The picture shows a modified gourd with elbow in place at the highest point which will push out the hot air as it rises. Know that in Northern climates you may have to plug these vents inn the early spring in times of cold weather to keep your martins warm.

Other tricks folks employ:

Using a frozen gel pack placed in an empty compartment. A frozen bottle of water can be used also.

A secondary shade can also help. Placing a sunshade to keep the sun from beating down on the house surface can decrease temps.

-------photo by OakleyOriginals on Flickr

Even a misting system has been used by many with success. Just makes sure the water does not go into compartments which would lead to wet nests. Also the misters should only run intermittently in the hottest part of the day so that the water can dry off. The evaporation is what cools. Don’t let the misters run at night or continuously. Our Free Purple Martin House Plans page has instructions available on how to make a mister system for your martin houses.

Hunger is a difficult problem and the debate is heated on how much humans should intervene on this. Though supplemental feeding is often done in early spring cold snaps for returning adults, one should strongly weigh the consequences of feeding purple martin nestlings. Remember that if you have several nests that are doing poorly from lack of food, the parents are suffering also. If there is a long term problem, supplemental feeding is a very short term solution. Read our Emergencies page for first responder care of purple martins.

What other problems lead to Purple Martin nestling Jumpers? Let us know what you think.

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(c)2011 www.PurpleMartins-R-Us.com

Time after time, this season, I have received calls from landlords concerning dead purple martin nestlings. I myself have found several jumpers this season. Jumpers are nestlings that are far too young to fledge but jump out of their nests for whatever reason. Usually extreme heat, hunger or parasites are the culprits that lead a martin nestling to such a desperate act. I liken it to people trapped in a high rise that is ablaze. The victims jump to their death to escape the fire.

This year South Florida is suffering from record drought conditions. In droughts flying bugs are significantly decreased leading to catastrophic food shortages. Nothing but rain can re-establish the equilibrium of the food chain. Since our weather is usually fair, our population of purple martins is not familiar with supplemental feedings. In some emergency situations like extreme cold, purple martins can be trained to accept food from an elevated tray or Bed & Breakfast type feeder. Unfortunately, when the weather is fair enough to fly and catch some bugs, the birds will just forage longer and farther from the nest. So training them to accept feedings is extremely difficult. To see a video of supplemental feeding of purple martins click here.

In the usual activity of a purple martin nest you will see some of the nestlings at the entrance waiting to be fed while others are sitting in the back of the nest resting. As the ones in front are continuously fed and get full they turn around and retreat to the back of the nest to sleep, digest and grow. The nestlings that were resting and digesting then get hungry again and come back to the front of the nest to take their place at the entrance to wait for a mouthful of bugs. The nestlings are in a continual carousel of being fed, keeping the parents busy feeding a nest full of an average of 5. But when the nestlings are not getting enough food then they all cluster at the front. So these “jumpers” can actually be accidentally pushed out by the jostling of the babies at the entrance for food.

Martin nestlings that jump due to starvation are usually doomed as the accompanying dehydration is far more deadly than the hunger. Since all purple martin nestlings water intake comes from the insects that the parents bring, in cases like this the jumpers are all very dehydrated. Not wanting to sound like a pessimist, there is not much that can be done. Feeding a dehydrated and malnourished nestling can cause it to just die faster. Looking at the jumper you can often see clues as to how well fed they are or are not. A pronounced keel (breast bone) shows lack of muscle development from chronic malnourishment. Dry, flaky skin is a sign of dehydration. A  wildlife rehabilitator would also look for signs such as skin turgor or “tenting” of the skin as a sign. Emergency injections under the skin would then be given BEFORE any feedings would be attempted. Water or other liquids can aspirate and kill birds quickly if given by mouth. This article on Hydration of Purple Martins can answer some questions and prevent more harm from being done while a rehabilitator is contacted. If their are other nestlings in the nest sometimes the weaker nestlings “jumping” can increase the survival rate of the nestlings left in the nest. If the jumpers can be hydrated then fed by a rehabilitator, they can often be reintroduced into the nest when the are approaching 21 days old before they fledge. Nest checks become increasingly important to know the age of the nestlings. As lowering housing may sometimes cause fledglings to prematurely fledge out of fright.

Though we provide housing for these wonderful birds, one can’t feel responsible for acts of nature such as drought. We help as best we can and give them a chance to survive. Next year they will return and hopefully with better weather conditions. We learn from our experiences and the next season will bring another chance at life.

Look out for our next entry on some of the other causes of “jumpers”.

(c) 2011 PurpleMartins-R-Us.com

Today I received a question and I thought I would share it with you. This DOES NOT pertain to T-14 or Cedar Suites wood houses which use winch / pulley systems and high grade poles designed for the weight of these houses that weigh from 65 to over 100 pounds.

Question

I have a purple martin wooden house that weighs 35lbs. I need to purchase the pole and the plate to set it up. Please recommend the best pole and plate to use to set it up.

ANSWER

It depends on what type of wooden house it is. Is it home made or store
bought? DIY Purple Martin houses that are just flat wood on the bottom, folks mount it to a 4×4 wooden post bought at a lumber yard or home improvement yard. The weight of the house will make it too heavy for a telescopic pole.

Though some websites may say that a telescopic pole can handle up to 25 lbs and sell brackets, galvanized pole or pipe FLANGES can be found in any hardware store. It would be cheaper for you to buy at Lowes, Home Depot or any local hardware store. We do not sell them due to safety concerns. We believe that the weight of the house combined with the height at which martin houses are mounted, substantially increases the risk of pole failure. Though we sell aluminum houses that use galvanized pipe, these
houses have been tested and are proven to support the weight they are designed for.

If you mount to a wooden 4×4 wood post then the base of the house can be screwed onto a post using “L” brackets, also found at any hardware store for under a few dollars.

Unfortunately many wooden purple martin houses sold on the web are poor choices to actually house martins. They are not built with martins in mind. Which is why we do not sell them.

Any good purple martin house will have large 6×12 (or even 6×11) compartments and the ability to selectively open portions of the house with minimal disruption. Easy to lower and SREH options show that your and your martins comes first.

When do you stop doing nest checks? When the nestlings reach about 23 days old. Some folks say 20 days old, but that seems overly cautious to me. All nest checks are on hold as their are tons of nests ready to fledge any day now. The nests that have fledged (about 8 of them so far) are creating much excitement as they peek into compartments and try to steal food from smaller younger nestlings.

A hawk made a late pass right before dark tonight and I am not sure if he was successful or not. The entire colony flew up in masse and with such an uproar of alarm calls that I am sure some bird was taken. Those early morning and late evening attacks are often quite successful. I will have to stay out later tomorrow and see.

I am not sure when the low hanging gourds are due to fledge soon. It will be interesting to see how the youngsters take to the air without having the advantage of height to get them airborne.

Eggs: 114
Young: 89
Compartments Available:43
Compartments Occupied wit eggs and or young:43

It seems like this is a yearly event. (knock on wood) I hope only once a year is my lot in my landlord life. It could be more, I suppose. It definitely could be worse. So far no lasting effects, other than some worry on my part and some moments of terror on the part of the martins that I had to extricate from the sreh gourds. 2 ASY males, one stuck in the sreh and one within the nest. Gratefully and gently freed. They are so amazing to look at up close.

For those that don’t know, Wing Entrapment is when a purple martin becomes stuck in a SREH. It usually happens when 2 or more martins are fighting over a compartment (nest spot) of any gourd or house with SREH (Starling Resistant Entrance Hole) As one bird tries to leave the nest and is trying to fend off attacks from within the nest from a rival or occupant, the bird gets stuck in the entrance. Basically gets stuck when he turns as he is trying to exit. If not discovered fairly quickly the birds in the nest can die as can the stuck bird. I wonder if vented rooms vs non vented rooms have a better survival time and if the deaths are strictly due to the heat build up in a nest with a plugged entrance? Or is it a dehydration issue? Those that have reported deaths from entrapment usually say that they discovered it either the same day or within a day or two of the event.

You can read about wing entrapment in previous blog posts as well as on our parent website, www.PurpleMartins-R-Us.com. Is wing entrapment a reason to not use SREH? Absolutely not. Wing entrapment remains much less common than the threat of Starlings in an unprotected colony. Of course, you have to weigh the pros and cons in your colony along with your sites individual risk factors for both problems.

I was poking around Twitter last night and came upon a tweet from someone saying that their purple martins had returned and were again starting to build a nest under their eave of the persons home. I had to chuckle since I knew  it was no Purple Martin. As many serious birders will tell you, one of the most important facts in properly identifying a bird is knowing the birds range, behavior and habitat. This person makes a perfect example. Knowing that purple martins do not nest on house eaves makes it easy to correctly I.D this bird as a Barn Swallow. Commonly mistaken by the novice birder, many of the swallow species like Purple Martins, Tree swallows, Barn Swallows can be confusing to some. Add in there Rough Wing Swallows and Violet-Green Swallows and even Bank Swallows, even the experience birders will have to look closely and carefully to distinguish these birds from one another.Heck, I wouldn’t have been able to tell a Rough Wing Swallow from a SY Purple Martin before reading up on it myself.

I found a great little site with some great photo comparisons of these commonly mistaken birds at BirdingIsFun.com which has some great tips to help you quickly tell these apart. As for the person tweeting about the purple martins mud nest under the eave of their home, I don’t think they care. But still it makes me think of how many people are out there convinced they are helping martins who may not be? Every year I hear from well meaning people that place housing and tell me about the bright yellow bills of their purple martins or how their martins will not allow other martins to nest in the house. Inevitably I find out that starlings nesting or Tree Swallows are dominating the house. Not to compare a Starling factory with a pair of Tree Swallows, but both examples show how purple martins can be pushed aside.

I recommend our Purple Martin vs Starling ID page to help those that are new to the world of birding. It is a side by side comparison of Purple Martins and Starlings. Even if you are not new, take a look and be sure…If I had a dollar for every time someone swears they have Martins and come to find out they are not!

Another great resource we recently added to our parent site was the addition of Daniel C. Drew, M.D. page on Tree Swallow/Purple Martin and Bluebird/Purple Martin INTERFERENCE. With his permission we added this page to our site so that new landlords can be more successful in getting purple martins in their Martin housing and Tree Swallows and Bluebirds in their respective housing as well. Though that page is up again, in its original site we both thought that the information contained within it is vital to new landlords that have lots of tree swallows and bluebirds but no luck in attracting Purple Martins to their properly set up site.