Purple Martin


Throughout the years, there have been many myths and misunderstandings about purple martins that have been passed down from generation to generation.  Many times these myths have been detrimental to the health and welfare of the martins.  In this section, I'd like to address a few of them and give explanations as to how they were developed and the truth about them. 



Martins eat 2000 mosquitoes a day:



Probably one of the biggest misconceptions that people have about purple martins is that they eat 'thousands of mosquitoes' every day. Many years ago, an aluminum house manufacturer coined the phrase "Purple Martins can eat 2000 mosquitoes a day" and it's stuck ever since.  Well, I hate to say it, but they are correct.  Purple Martins CAN eat 2000 mosquitoes a day.  Unfortunately, the truth is, they don't.  In fact, the statement is very carefully worded so that the uneducated public believes that if they buy a martin house and attract purple martins, then their mosquito woes are over.


And how did this all come about?

Long story short; back in the 1930's a man from Louisiana did a study on the stomach contents of some martins found on a bridge that were killed by cars to see what they were eating.  What he found was that they contained about 2000 mosquitoes, however; they were "Salt Water Marsh Mosquitoes", a much larger species of mosquitoes than the ones that bite us.  They are about the size of 'Cane flies'.  The aluminum house manufacturer got hold of these studies and decided to include them in his advertising on his houses and he came up with the phrase "Purple Martins can eat 2000 mosquitoes a day".  However; he neglected to state that they were 'Salt Water Marsh Mosquitoes'.  People saw his boxes and, having mosquito issues of their own, decided to buy the house and attract martins so that they could eat all the mosquitoes in their back yards.  Unfortunately, they were very disappointed when it didn't happen.


Just like any other creature of nature, martins are opportunistic eaters and will take the largest and most readily available food at the time, and according to the studies done over the years, mosquitoes are no where near the top of that list. In fact, some of the research showed that mosquitoes, the ones that bite us, were less than 2 % of the martins' diet.


Now, let's dig a little deeper into this subject on our own.


First, let's put our heads together and stop to think about something.  


When is it that mosquitoes become the worst?  Around dusk to after dark!  

And, when do all daytime birds go to sleep?  Around dusk to after dark!  

So, there's one reason the statement is false.


Second, mosquitoes like to stay close to the ground, where there're bushes to hide in and it's damp.

Martins like to eat high in the air, sometimes as high as 300 and 400 feet.

Another reason they don't cross paths.


Third, the favorite prey for a martin is a dragonfly, the mosquitoes' worst nightmare.  Dragonflies prey on mosquito larva, therefore, it could be said that martins are actually helping the mosquito out by killing it's aggressor.


And forth, mosquitoes hang out in your back yard, in your bushes and near your house.  Martins are known to feed a rather large distance away from their home site so as not to attract the attention of predators.  Again, they do nothing for your own personal welfare as far as mosquitoes are concerned.

Now this is not intended to dissuade your beliefs about martins. I'm simply presenting the facts taken from studies done on the subject. This in no way detracts from the fact that these birds are still a joy to have around. If they weren't, I wouldn't be here trying to persuade you to try and attract them.


And, if you really have a mosquito problem I highly suggest you look into some other form of control.  Purple Martins are not the answer.  I have a fairly good colony of martins and I also have a fairly good population of mosquitoes.  Bats are a known mosquito eater so I would suggest putting up a bat house and attracting them to help with your mosquito issues.





Scouts come, check out the area and then go back south and get the rest of the flock:



This myth come about because people would see the first scouts return for the year and then disappear for a couple of days and then suddenly show up with more birds.  However, they didn't go back to get the rest of the flock.  The first martins are simply here because they are usually the most mature birds and are the first to return.  Then, since they are wild birds, they are simply being wild and flying around and still roosting in trees somewhere.  Once more birds start returning, (on their own), they begin congregating at their home sites and begin staying at the houses and gourds.  Thus, it looks like the first scout went back to get them.


And think about this.  The purple martin migration lasts for about 8 to 10 weeks, with birds trickling in, by 2's and 3's at a time, therefore; there is no "flock" as such.





Aluminum houses are good because the aluminum doesn't harbor insect pests like wood does.



Absolutely false.  True, the insects can't burrow into the aluminum to hide, but insect pests don't hind in the housing materials itself, they hide in the nesting materials and since ALL houses have nesting materials, then ALL houses can contain insect pests, mainly nest mites, blowflies and fleas.  This statement is nothing more than just another sales gimmick directed at the un-informed public.





Just put a house or gourds up and they will come.



This may have been true at one time, but unfortunately, it's no longer true now.  Martins have many predators and competitors and two of the worst are the European Starling and English House Sparrow.  These two introduced species (back in the 1890's) have multiplied exponentially and become a plague to purple martin landlords (as well as farmers and other business owners).  BOTH are very aggressive and will not only usurp the martin's cavity, but will often kill the martins in doing it.  A lot of work has to go into protecting a martin colony and some of the old ways are no longer viable for keeping these birds.  Today, if a potential landlord wants a colony of martins, they have to educate themselves with all the recent findings and discoveries in the hobby and then follow them so that the martins will be able to raise their young without too much aggression from outside forces.





Martins can take care of themselves when other birds nest in their houses.



Again, this is false.  Again, at one time in history, this might have been true, but in recent years, Starlings and Sparrows have become such strong competitors for housing that the martins are now having to constantly fight them off and the landlord has to intervene if he wants to maintain a colony.  Both of these competitors have very strong beaks and in 'one on one' battles, the martin will lose every time.  In fact, the starlings will not only destroy the eggs and kill the young, but if they are able to trap the adult in the compartment, then they will kill the adult birds as well.

As for the Sparrow, they will "pin" (peck small hole) in the martin's eggs and that renders them infertile.  They will also kill any young martins and then simply build their nest right on top of the dead young.

These two reasons alone should be enough to insure that no other birds nest in your martin housing, regardless of what anyone else tells you.


As a side note, bluebirds as well, are also affected by sparrows for the same reason as martins.





The proper size for a purple martin compartment is 6" x 6" x 6" with an entrance hole of 2".



Old school and incorrect.  Once again, let's stop to think.  An adult purple martin is approximately 8" long and about 2" wide.  It takes two adults to make and raise a brood of young birds.  If we do the numbers;

First, the adult birds can't fit properly into a 6" space (very comfortably).  8 just doesn't go into 6. 

Second, if both parents are in the compartment at the same time, then that's 4" used up of the 6" width that's available.  That leaves only enough room for 'one' more bird.  But the average clutch for a pair of martins is approx 4 to 5 young.  (Numbers taken from houses with larger compartments).  Therefore; where are all the other young birds going to stay.  One baby per adult pair isn't even enough to sustain the species from natural attrition.  Recent research has shown that martins will double their clutch size when compartments are enlarged.  Today, it's highly recommended that the small compartments in the aluminum houses (and many other houses on the market) be enlarged to 6" x 6" x 12" by either removing the rear middle panel or drilling a 2" diameter hole in it, and turning two compartments into one.  Some aluminum houses are designed in the octagonal shape and enlarging this form of housing is very difficult.  In this version, every other 'side' panel has to be removed so the compartment can be enlarged 'side ways'.

Third, the round 2" entrance hole is no longer the recommended type of hole to use for purple martins.  Again, recent research has shown that the major majority of European Starlings cannot access the new crescent shaped entrance holes.  This one discovery alone has changed the entire purple martin hobby from being a pain to being enjoyable again.  No longer does the landlord have to fight off all the starlings that are constantly trying to take over his housing.  With this one species held at bay, the landlord can now concentrate on the other pest species, the English House Sparrow.  Because they are smaller, they can easily enter the SREH entrances so trapping, shooting, whatever it takes is required to control them.

And four, the deeper compartments allow for the martins to back out of the way when danger comes calling.  With the smaller compartment sizes, the martins are in easy reach of predators and were easy meals.  But with the 12" deep compartments, the martins can hide in the back and are well out of harms way.  One more reason to make the change to larger compartments.





European Starlings don't like to nest in gourds because they swing.



Pure and total BUNK.  The only reason starlings won't nest in gourds is if they are TOO SMALL.  Starlings like a lot of room for their nests and in fact, will fill an entire five gallon bucket with nesting material just to make a nice roomy nest.

Now, if you don't believe me, a simple little test can be done.  Under your martin housing, hang a small 6 inch gourd.  Then, right next to it, hang a nice 10 or 11 inch gourd.  Paint them both white so that there is no difference in them other than the size.  In both gourds, drill a 2" round entrance hole.  Now, sit back and watch what happens.  If there are starlings in the area, they'll find those gourds and 100% of the time, they'll pick that large gourd.  In fact, the test can even be expanded a little further.  On the large gourd only, change the hole to a 1 3/16" crescent shaped SREH hole and again, sit and watch what happens.  Even though the smaller gourd has a 2 inch entrance hole, the starlings will literally struggle to enter the larger one with the SREH.

This is also why starlings don't like the smaller compartments in many of the aluminum houses that are on the market.  Small compartments keeps them out, NOT the swinging action.





So now you know the truths about a few of the myths about purple martins.  Next time you talk to someone that passes on these myths, you'll know that they are probably un-informed about the subject and should be corrected.  However, be forewarned.  Some people hold onto these myths pretty hard because, "that's the way the old folks believed" and just simply refuse to change their thinking to believe modern research findings.  If you like, print out this page and hand it to them if you want to reinforce your statements.