Purple Martin Propagators

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Purple Martin History



HOW IT ALL BEGAN



Purple martins are the largest swallow in North America and are known as Aerial Insectivores (which means they only eat insects that are caught while in flight - not off the ground). Each bird can consume up to 2000 insects every day (mosquitos, wasp, ballooning spiders, gnats, grass hoppers, etc.). This natural method of flying insect control was observed by native American Indians who, for thousands of years, hung hollowed-out gourds in and around their villages to provide nesting cavities that would attract this very beneficial bird species. Over time this created the only semi-domesticated migratory bird in North America. The purple martins learned that people scar off predators wanting to get at their nest filled with eggs and baby birds. This is the reason a Purple Martin Housing System should not be placed more than 150' from homes or places people gather around in groups on a fairly regular basis.




SECONDARY CAVITY DWELLERS



Purple martins only raise their young in completely enclosed nesting compartments known as cavities. "Secondary" means that purple martins do not build their nesting cavities like wood peckers. Instead, they will migrate back to North America early enough to find empty cavities to raise their young to the fledgling (flight) stage of development. Those cavities had quite spacious interiors for raising lots of babies all at once. Purple Martins only raise one brood (set of eggs) a year. Other bird species will raise 2-3 broods every season.



CAVITY SIZE MATTERS



Purple martins are a lot larger than they appear while in flight. Their bodies are over 7" long with a tip-to-tip wing span exceeding 15" across. In order for them to raise large numbers of fledglings every year, they need the nesting cavity to be much bigger than each individual bird, especially since it must accommodate both adult birds as well as all of the babies. What most people don't know is that the babies are about 20% bigger than their parents just prior to making their first flight from all the excess baby fat they have put on.


In order for the purple martin population to remain at healthy numbers, their nesting compartment needs to have approximately 77 square inches of floor space. Predators want to invade their nest which is why the nesting compartments should be longer inside than their width. This will keep invaders from being able to reach the "nest cup" which is always at the far back of the cavity. Minimum width should not be less than 7" because the only thing that bends on a bird is its neck (thus allowing the martins to easily turn around inside their nest). Doing the math, this means the nesting compartment needs to be 7" wide by 11" long. Anything smaller than this WILL REDUCE the martin population.



IMPROPERLY DESIGNED
PURPLE MARTIN HOUSE



This is a purple martin bird house that was designed back in the early 1960's by a company named Nature House in Griggsville, IL. There are many flaws that hurt the purple martin population. Compartments are only 6"x 6" square (that's a total of 36 square inches of floor space). Why would anyone make a house for purple martins with a nesting compartment that is smaller than the bird it is made for? It is very easy for predators to reach into the compartments and grab eggs/babies out of them. These houses are made out of metal which is the best conductor of the sun's heat directly into the nesting compartments. Flimsy swing-up doors pop open in high winds exposing eggs/babies to the elements. Cheap thin metal like this can be torn apart in high winds (and it has been the cause of many a bad cut on hands when cleaning them out). Most houses like this NEVER get 100% occupied because of MALE PORCH DONIMANCE (male purple martins DO NOT like having another male on the same porch). Round entry holes allow birds like European Starlings to build in them. They are the perfect size for English House Sparrows.



ENGLISH HOUSE SPARROW



This bird is from England. In 1850, the Director of the Brookland Institute, Nicolas Pike, had 8 pairs imported to New York where they were released (their common name in Europe is simply house sparrow). They are invasive to the American continent. These aggressive birds are killing off many of our native bird species. They do this by breaking eggs or killing the babies in other bird's nest and then taking over that nest to raise their species. If you look at the beak, you will see that it is shaped like that of a parrot. It is very strong and every year there are many reports of sparrows even killing full adult purple martins (the beak on martins is only solid for the last 1/3 past the nostrils while the other 2/3 back under the ears is soft membrane for catching and holding insects that they bring back to feed to their young). Unfortunately, house sparrows are much smaller than purple martins. Therefore, any entry hole that a martin can fit into, so can invasive sparrows.



European Starling



This bird was introduced to America by an amateur ornithologist named Eugene Schieffelin. He belonged to the American Acclimatization Society that at that time in history believed introducing non-native species was a "fashionable" thing to do (having no knowledge of the consequences this would have on native ecosystems). In 1890, he released 60 European starlings in New York's Central Park with the hopes they would eat pesky flying insects. Like purple martins, these birds also live in cavities to protect their babies. Unlike most of our native American birds that have very light-weight body structures, starlings are extremely muscular. They are about 30% heavier than native birds the same size. This gives them a huge advantage when fighting for the few precious nesting compartments available in nature.



controlling the invaders



English house sparrows and European starlings must be trapped and eliminated that are trying to take over your purple martin houses. If you simply trap them and then drive 50 miles away to release them, they will fly back to your purple martin house and get there before you get back home. This is how you eliminate these birds.

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WARNING: THIS IS NOT FOR THE FAINT-OF-HEART!!!
============================================================ Above on the entry to the gourd you can see the metal slide plate that is part of the trapping system. This is ONLY SET UP on a gourd that an invasive bird is building a nest in. Once that bird re-enters the gourd, it will trip the trap. The metal slide plate falls down locking them inside. Removal is easy. Place a bread bag over the entry, lift the plate and let it fly into bag. Make the invader go to the bottom of the bag. Tightly wrap the bag around it. After several minutes it will pass out from lack of oxygen (up to now it hasn't felt any pain, making this a humane way to euthanize it). After about 10 more minutes, its brain finally shuts down. Now you can dispose of it anyway you want.



Requirements for
Purple Martins



HOW MANY COMPARTMENTS



Purple martins are communal colony birds that like to nest together in large numbers. They have learned over thousands of years that by living in large clusters of nesting compartments there is an added safety from aerial predators like hawks and falcons. After many decades of research, it is now known that the minimum number of nesting compartments needed to establish a new colony is twelve (12). That is the only thing they got right in the above metal condominium house. Anything with fewer nesting compartments WILL NOT WORK. New purple martin colonies can start with 12 gourds, but we've learned that having more compartments actually helps you get a new colony started up much quicker.



WHERE TO INSTALL HOUSING



Purple martins are pretty finicky when it comes to the placement of their housing systems. These birds have learned that having their nest too close to trees or buildings much taller than their housing system gives predator birds an advantage to pick them off as a meal. Also, when the martins take off, they WILL NOT fly a circular pattern to get above those tall structures. They come out of their nest and fly a straight line at about a 30 degree incline to gain altitude up to where the insects are swarming. In the above sketch, it shows that the most ideal placement is to have at least 40' in all directions from the pole to those taller objects.



WHY GOURD-SHAPED



Purple martins originally lived in abandoned woodpecker nest or inside crevices along cliff walls. But after living in gourds hung up by native Americans for thousands of years, that gourd shape is now permanently ingrained into their genetics as a place to raise their young. This is the main reason we only sell and install housing systems made to look like gourds. Above is an older Super Gourd that was designed by James Hill (founder of the Purple Martin Conservation Association back in 1967). As you can see, the entry hole is no longer round. This was the first re-design done to try and keep European starlings out of the purple martin's nest. There have been many different styles of entry holes put on martin houses, but the starlings are very smart birds and have learned how to "squeeze" into all of them. Below is our newest gourd design.



VERTICAL GOURD
PURPLE MARTIN HOUSE



This is the most up-to-date purple martin gourd bird house on the market. The main difference you will notice is that the gourd isn't round, but rectangular. This allows for the longer distance from the entry to the nesting cup at the back of the gourd. Also, the tunnel attached to the front of the gourd allows the purple martin landlord the ability to easily replace the entrance as new information is learned about how to make the gourds safer for the martins. The current version has what is known as a Connely II entrance that does discourage large older starlings from entering.



INVADER TRAP


The wire with the loop at the end is the tripping mechanism that goes into the tiny hole above the entrance and is set from inside the gourd.


PRE-NESTING GOURDS


This shows a landlord placing a big handful of pine straw (pine needles) into every gourd just prior to when the purple martins return from Brazil. This is necessary because if the gourds are hung up empty, the slick floor will cause the martins to splay their hips. But, we have learned that there is a big payoff from pre-nesting. An empty gourd isn't very good at encouraging the martins to enter them. Also, it can take martins 5-7 weeks to build the nest from scratch. We now know that a pre-nested compartment encourages the martins to start laying eggs much earlier than normal and they are averaging two (2) more eggs in the brood since they aren't expending lots of energy gathering and carrying all that nesting material up to the gourds.


WHEN WILL THEY ARRIVE



Purple martins only eat flying insects, therefore, they must migrate in the fall to a place where there is an abundance of food during our winter months. All martins fly south of the equator to Brazil. They do not mate up there (reproduction only takes place in North America). While there, they molt all of their feathers. Male purple martins between their 2nd and 3rd year of life undergo a dramatic plumage change as they reach full sexual maturity. The new purple feathers are what gives them their common name - Purple Martins.


Shortly after winter solstice in December, purple martins start their migration back to North America. Unlike most migratory birds, though, the martins do not fly as a flock but instead fly back as individual birds. The migration map shows the approximate dates the first martins start showing up at established colonies.


The older ASY (After Second Year) martins almost always return to the same bird house they used the preceding year. This is known as nest-site-fidelity. The younger SY (Second Year) martins stay in Brazil for 6-8 weeks longer than the older martins, so when they return back to the house they were born in, it is already full of the ASY birds (the SY's now have to find another housing system to live in). This is why many landlords will put up additional housing systems every few years.


The female martins lay one (1) egg a day, but don't start incubating them until the last egg is laid. It then only takes sixteen (16) days for the eggs to hatch, all on the same day, usually. Both the male and female will now spend the next thirty (30) days catching whole insects and bringing them back to feed their young. Then the young will all fledge the nest and be on their own.


It is OK to raise and lower your purple martin housing system even with babies in the compartments. The adult birds will get accustomed to your doing nest checks to make sure everything is going according to plan. Some people even number the gourds to keep detailed records of how many eggs are laid and how many grew up to fledge from their housing system.


After the purple martins leave in the fall, bring the gourds down and clean them out. All that is required is for you to break up the solid nesting material and dump it out. You DO NOT need to wash and scrub the insides. Studies indicate that the older martins, the ones that raise the most young, actually prefer dirty interiors.


As you can see, it really is easy to establish and maintain a purple martin colony. For some reason, there are web sites out there trying to make it a complicated endeavor. Watching your colony return every year gives you a sense that there is a way for you to help out our natural environment (even if you live in a city). The male below and PM Propagators want you as a landlord.