The Nanaimo News Bulletin in BC Canada featured another article on our Western purple martins a few days ago. It’s hard to believe that the season is still winding down for our Canadian neighbors. As the final day of summer approaches, it’s almost a “last hurrah” of sorts for us here in the extreme Southern range of the Eastern species.
It is nice to hear that despite the poor weather they still managed to have a good year and some 585 pairs that managed to produce some 2,200 baby martins. 110 of those pairs within the Nanaimo area itself.
Of course you can read the entire article by clicking on the picture or visit www.georgiabasin.ca or www.saveourmartins.org.
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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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”.
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.
Tropical Storm Bonnie Passes with a Whimper But Scoots Martins Out
The last nest of 2 martin fledglings (which were a complete surprise) fledged the same day that Bonnie was supposed to dump rain all along the coast. Fortunately for some, the rain was more of a short drizzle but amazingly the purple martins seemed to know something was up.
Every morning our colony would get a faithful dozen or so visitors that would sit on the housing and chatter away. By about 11 AM they would leave only to return again the next morning. But the day after Bonnie not a purple feather was to be seen. Many speculate that birds, being so 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. Could it be coincidence?
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, the season is over here in South Florida and all martins have left.
Not that my birds needed a Tropical Storm 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.
It’s official, the last of the nests have fledged and all the babies have taken to the air. A hawk was making daily visits and though I am sure (s)he got at least 2 fledglings, I am sure more fell victim. I was unable to get a good look so I am hoping it was the resident Red Shouldered Hawk, a slower and larger hawk that poses a formidable threat but less so than the smaller faster Coopers Hawk that are common in South Florida also.
The Red Shouldered hawks nest close by and protect this as their territory from other hawks. If that can be counted as protection…I am not too sure.
Night time is quiet and I am not sure if many martins are returning to the nests to roost at night. They may have moved on to a local assembly area or pre-migratory roost. The fact that I am talking about the roosts already almost sounds crazy! Can time have flown by so fast? I guess I will start planning another trip to the roost in Davie this year. It has almost been exactly a year since I went to see it and video taped it. You can see it at my blog post titled Purple Martin Pre-Migratory Roost Spectacular. It is a great YouTube clip taken at the roost with swarms of purple martins.
The webcam will not be up again for the remainder of this year as the computer I had it running on is dead. I plan on replacing it as soon as I can and it will be up again next January. I promise.
Over the last 3 days purple martins have been fledging left and right, taking to the air robustly without a hitch. I have witnessed several nests from both racks fledge and all the parents seemed to be ecstatic. The energy level of the colony is through the roof as the morning social doesn’t let up until well after noon. Birds are flying about in large swooping circles about the colony site. In groups of one youngster to several adults who seem to be guiding the birds into the sky. Several spots on the electrical wires seem to be gathering spots for the youngsters and the rainy afternoons are enjoyed by all. Just enough rain to cool things off but not enough to drive food out of the skies for long.
Last year I wrote a blog post called SY Males-The Enemy Within. It dealt with some of the facts and dangers that Purple Martins face from their own kind. SY or subadult male purple martins, arrive later than the ASY martins. They return home having survived the migration only to find all nest compartments full or guarded by protective ASY males. Eggs and nestlings run the risk of being destroyed or killed by the younger SY males. These males are so eager to breed that they will kill their own kind to force the females to start a new family.
Today I found the first casualty and my nest check results show that several nests have been affected by these SY males. The first tip off is a compartment previously claimed by a ASY pair is now protected by a SY male. Eggs or nestlings on the ground are dead give aways of course and the bickering and fighting can get intense. Though unless witnessed, you may never really know what was the cause of eggs or nestlings that mysteriously disappear, in the absence of sparrows and starlings, one can assume that SY’s play a part.
Can something be done about this? Well, many people wait until the SY males arrival to open up some of their housing. Others put up temporary type housing to alleviate some of the nest site competition like the Trendsetter Create-A-Rack Arms that can be added on to your telescopic pole to make an affordable and easy spot to hang a few extra gourds in a pinch. Still others may yell and shoo those pesky SY males away.
In the grand scheme I suppose I tolerate this behavior in my colony as the ugly harsh reality of survival. If a ASY male is off guard and not protecting his mate and nest, his gene pool suffers. Those males that are dutiful in their jobs as protectors can drive away would be dangers and their off spring survives. It is a hard thing to witness and if I witness the tossing of a nestling I will intervene and return it to its nest. Is that what National Geographic would do if they were filming a documentary? No, they would probably film it happening and talk about the harsh reality of nature and watch death come slowly. Is that interfering with nature? Or is it our nature to interfere?
I was torn between relief and despair when I found out on Aug 26 that the last remaining purple martin at the Busch Wildlife Center was released at some point.
I had forwarded some information to the folks at Busch Wildlife Center regarding some of the latest, cutting edge information on the releasing of rehabilitated fledgelings. It was on the post Update On Late Nest Martins at Rehabber. In short, the preliminary data highlighted the dismal survival rate of purple martins released without benefit of the post fledging instruction period given by the parent purple martins. The same info also pointed out a potential revolutionary approach to their release. Last year 3 martins were released AFTER being taught (in a flight cage) how to catch flying insects and 1 of the 3 returned to the natal colony this year. This information is groundbreaking and could give new hope to fledgling purple martins released after rehabilitation.
I am unsure if this martin that was released had the benefit of being “taught” the basic survival skill of feeding or even if it was released with other martins which is what is recommended by the PMCA.
I do know that if the bird was released without any other purple martins around that it is dead. Purple Martins, unlike some birds, seem to require a period of post fledgeing instruction
As of this time, I have not received any reply to my email to Busch Wildlife .
On another birding note, a large group of about 15+ nighthawks was moving south bound through the area. Tons of barn swallows feeding in the orange groves nearby also. Fall migration is in full swing.
I thought being in the South that I was safe from Blow Flies (Protocalliphora sialia) but alas after talking to a few folks and doing some research I am sure I have experienced a more sinister type of Blow Fly here at my colony.
A few weeks ago I posted about a nestling that had some sort of “lump” or cyst on its abdomen. The nestling died soon thereafter. Since then I have been doing a little digging into what it actually was. When I found the dead nestling it was quite apparent that the mass had opened and since I saw no other injuries or obvious issues with the nestling, that very well may be what killed the bird.
This led me on a quest to find out what may have been the cause. At first I thought they were Bot Flies. What is a Bot fly? Well, in short it is an insect that’s larvae lives as a parasite within the tissues of a living organism. Horses commonly get them as do other mammals. I have since come to learn that there is a type of subcutaneous BlowFly (Trypocalliphora braueri) or a type of Housefly (Philornis sp) that may be to blame.
I realized it wasn’t just me when I was reading my latest issue of “Feathers and Friends” (a magazine published by “The American Bird Conservation Association”) I read about several landlords reporting birds with “bubbles” that are “caused by an insect that laid eggs there and the eggs hatch into little worms” When I read this, It sure sounded like a BotFly.
I spoke with Mr.Terry Whitworth, PhD, who is the Adjunct Professor of Entomology for Washington State University. A portion of his email to me was as follows, ” There are two possible culprits in Florida, one is Trypocalliphora braueri, a subcutaneous blow fly. The other is Philornis, a Muscidae (a type of house fly) that occurs in Florida. By the time the larva comes to the surface where the bump can be seen the damage is done. Removing it or killing it at that point will not change things much for the nestlings. Neither pest is always lethal, it depends on the number of larvae that develop and where they burrow. I once took 25 mature Trypocalliphora larvae off a nestling junco and it survived long enough to fledge.”
Whether they be Blowflies, Houseflies or Botflies, whatever you call them, these nasty bugs can kill! Though not the same bug they are somewhat related. Some infest by way of laying their eggs or larvae into living tissue. Others crawl up through the nests and suck blood only to drop into the nest to grow then repeat the process. Getting larger and needing more blood each time. Usually a “Northern” plight, Blow flies can be controlled via nest changes as Sevin has NO affect on the larvae. A pair of forceps or tweezers can be used to pull these nasty things off of the nestlings. Once the Blowfly larvae are done feeding and growing in larval stages they form a pupal case in which they remain, dormant, until they are ready to emerge as an adult. Something like a caterpillar forming a cocoon before it emerges as a butterfly.
The typical BlowFly, can exsanguinate a nestling when present in large enough numbers but if caught early are controllable. These other guys (Philornis, Trypocalliphora and Botflies) however spell bigger trouble.
You think I am dreaming this all up? Read this article by The University of Northern British Columbia. (Be warned, if you don’t like bug pictures…don’t click) Basically it explains how death can result several ways. The Bot larvae move around and migrate in the soft tissue and can kill the bird, the wound itself can become infected and kill the bird, the Bot larvae will feed on the tissue and weaken the bird to the point of death, the Bot can damage the wings and thus, “produce an obvious awkwardness in locomotion, which may render them more susceptible to predation.” (that is a direct quote) In short the damage is severe and serious.
And talk about BiZzArRe? There is even a species of Bot Fly that lays its eggs on mosquitoes.When the mosquito bites the eggs are transferred. What does that mean? That means look out! Humans can get it too! Still don’t believe me? Just Google it. But that is another story.
What can be done about these subcutaneous (under the skin) Flies? Unfortunately, nest changes may not be helpful as once the adult Fly lays the eggs/larvae they crawl onto the bird and burrow into the skin. Another options is pretty gruesome and may not be legal. Also, it may cause more problems than it solves. Now, I could explain how the skin is cleaned with an antiseptic such as betadine prior to making a small incision from which the Bot Larvae is removed with a pair of forceps or tweezers but I wouldn’t want anyone with paranoia cutting holes in a purple martin with a wart. And legally, I think I could get in trouble for telling people to perform surgery on a federally protected bird without some sort of Veterinary license. All of this may be a mute point as once the larvae are large enough to cause the visible lump, the damage to the birds soft tissue is done. As www.kingsnake.com puts it, “They develop under the skin of some birds.The bird has died after…maggots have consumed much of its muscle tissues. Once their host is dead, the larvae leave it to pupate…”
In humans, the true Bot Fly wound (which is open so the larvae can breathe) could be covered with petroleum jelly or some other occlusive salve so that the larvae will emerge on its own, seeking air to breathe, after a day or so. I think that on a bird this course of treatment would not be successful. How could you place a dressing on a bird? We have the issue of a pretty dirty living environment (a nest) talk about infection! So, basically the wisest course of action would be to take the bird to a wildlife rehabber.
Of course we also have the problem of not really being sure which one of these 3 flies is the true culprit. Perhaps it is a combination of the 3, maybe some other. In order to find the true source of this problem I urge all that may witness this to photograph any lumps you may see on your nestlings and monitor them. Of course you can email them to me at the “Contact Us” section.
It is important to stress that with the classic and somewhat common Blow Fly infestations, that nest changes are by far the easiest and best treatment. Elevated subfloors help and nest trays make cleaning your purple martin bird houses super easy. Pulling off any Blow Fly larvae that are latched on to the nestlings with tweezers. For those of you that have questions regarding nest changes, this short video may help you overcome any trepidations that you may have.
Sources:
If you want to learn more about Blow Flies or help with blowfly research go to www.birdblowfly.com for some interesting facts.
The American Bird Conservation Association / Feathers and Friends can be contacted via phone at (260) 768-8095 x:5 Subscription rates are $18 for 1 year. Tell them Susan from PurpleMartins-R-Us sent you!
The Nanaimo News Bulletin in BC Canada featured another article on our Western purple martins a few days ago. It’s hard to believe that the season is still winding down for our Canadian neighbors. As the final day of summer approaches, it’s almost a “last hurrah” of sorts for us here in the extreme Southern range of the Eastern species.
history of martins at our parent site:
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 
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.
It’s official, the last of the nests have fledged and all the babies have taken to the air. A hawk was making daily visits and though I am sure (s)he got at least 2 fledglings, I am sure more fell victim. I was unable to get a good look so I am hoping it was the resident Red Shouldered Hawk, a slower and larger hawk that poses a formidable threat but less so than the smaller faster Coopers Hawk that are common in South Florida also.
