Snakes are another problem.Other
Pests and Predators
Of
Purple Martins
Besides Starlings and Sparrows, there are other pests and predators that need controlling and on this page, we'll try and give info on how to control them.
Woodpeckers
Although these birds aren't usually a threat to the martins, what they do is ruin a wooden martin house by pecking at and enlarging the entrance holes. Squirrels will do the same thing by chewing the holes larger (which is why predator guards should be used). I've also had this happen on my S&S trap holes and my Bluebird houses. If SREH's are being used, about the only thing that can be done is to replace the SREH with a new one.
On a trap (and BB box) with a round hole, one thing that can be done to prevent the destruction of the entrance hole is to sandwich a piece of 1/16" thick aluminum in between two pieces of wood.
Here's what you do.
First, a new piece of wood has to be put back on to replace the one that was destroyed. This might mean a new front face to the trap (or BB box) if it's totally destroyed. Now, cut a 4 inch square piece of 1/16" thick aluminum. In the center of it, cut a hole the size you need. Normal wood cutting hole saws that fit in your drill are made of steel and will easily cut the hole in the aluminum. In each corner, drill a small hole that will allow mounting screws to pass through. Now, make another piece of 4 inch square wood, exactly the same as the aluminum. Lay the aluminum piece on the wood piece and match drill the main and 4 corner holes in the wooden block using the aluminum piece as a pattern. Now, screw the new piece of wood to the front of your trap (or BB box) with the aluminum sandwiched between the block and front face of the trap. When the wood pecker pecks the front piece of wood to open the hole, it hits the aluminum and can go no further. Although the outside hole is opened up considerably, the inside piece of wood is safe from the pesky woodpecker. I've had to do this to my S&S's and it works great. Plus, all the roughed up opening the woodpecker created makes for great claw holds for the 'proper', shall we say, tenants.
Snakes, Raccoons,
Squirrels, etc:
Another problem that you will eventually run into is climbing predators. Snakes,
Raccoons and Squirrels all love birds and bird's eggs. You can throw the
friendly family cat in this category also if they have a tendency to climb. One visit by one of these critters
will devastate a martin colony, especially if its small. Sometimes the parent
birds will get away, but any eggs or young birds will be lost. Yes, that cute
little squirrel will snatch an egg faster than you can blink an eye. He'll
also chew the entrance holes of a wooden house or gourd to beyond recognition
just to get at the contents inside.
Raccoons are physically strong and will tear an aluminum martin house apart trying to get at
the occupants. The tell tail signs of destruction (and chewed off wings on the
ground) are often the work of 'coons
that have scaled your pole and gotten into your martin house. Gourds are a
little more difficult for the 'coons to deal with because of their
swinging. This swinging make the 'coons feel uneasy and makes it difficult
for them to get at the contents. However, the swinging DOES NOT prevent
them from gaining access. If they are able to pull the gourd up to where
they are, they will then proceed to tear the gourd apart to get at the contents.
Snakes are another problem.
DO NOT BELIEVE THAT SNAKES CANNOT CLIMB A STEEL POLE.
In fact, a 4 or 5 foot rat snake will make it look easy. They are hardly even noticed slithering up the pole, often doing it at night, and once they gain the top, simply slither right in. Once they've obtained access, they don't leave until ALL occupants have been consumed. Some snakes are unbelievably good climbers when there is a meal at stake. We normally don't think that they can go up the surfaces of a smooth steel pole, but take it from me, I've personally removed a number of snakes from martin houses. Although not all snakes like to climb, there are a few that have no problem with it at all. The rat snake pictured here will readily and willingly clean out your martin house or gourds if given the chance. As you can see, we found this one in a T-14 compartment after it had feasted on the 4 chicks that were in it, and it was settled down to digest them before moving on. The T-14 is on an 18' high steel pole and at the time, the landlord didn't have predator guards on it.
It does now.
So what can be
done about these types of predators?
Believe it or not, these climbing predators are the easiest to keep from your
site. Just put up a good working, climbing predator guard. There are many
different styles available. You just have to decide which will work for you.
Purchase or make one, and then install it on the pole to your housing. If
properly installed, it will prevent any climbing creature from gaining access to
your housing by not allowing them to climb the pole.
If you
think you'd like to make one, check out this page
http://chuckspurplemartinpage.com/predgard.htm
Flying Predators:
Owls, Crows, and even Blue Jays will wreak havoc
at a Purple Martin site. These flying predators are interested in both the
parent birds and the eggs. Depending on the size of the colony, one successful
visit by one of these flying bandits will bring many more and before long, the
site could be considered destroyed. The parent birds that escape will quite
often abandon the site, never to return.
Coopers and Sharp Shinned Hawks are Raptors, meaning they normally only eat other birds. They are usually after the adults and fledglings and get their meals by surprising the birds by ambushing them. They will fly towards the site, usually with some obstruction between them and the colony, giving them some cover. Then, they suddenly appear from behind the cover, surprising the prey and the prey, (your martins) sometimes doesn't have time to react and the Raptors have a meal. This is why martins don't like to nest near trees. Trees give the hawks cover and allow them to ambush the martins, so this is why we say, put the martin house as far out from trees as possible. Enough successful attacks from hawks and the martins will leave the site for good.
Although Hawks hit just about any time, they will become more prevalent around fledging time when the young are just leaving the nest and learning to fly. The parent birds are very good flyers and can usually out maneuver these predators, but the young, inexperienced birds often fall victim to them. Although its natural, you still hate to see a new fledgling fall prey to one of these birds of prey.
Owls are probably the hardest to defend against out of these predators. They
usually hit at night and will quite often do their work without your even
knowing they were there, until it's too late. Often, the only way you will know
they've been to visit is from the tell tale claw marks all around the entrance
holes or maybe an owl feather on the ground. Sometimes, you'll notice the front
of a gourd that's been pulled off. That, and the parent birds will be gone.
Owls will often tear off the porches and some doors from aluminum houses to get
at their prey.
Crows and Jays can become bothersome pests also. They try to get at the eggs
and/or young. Although not usually destructive to the housing, they can also
cause the site to be abandoned if they are persistent enough.
What can be done to prevent these flying predators from getting at your
martins?
Prevention in this case will depend on the predator. Coopers and Sharp
shinned hawks usually attack from an ambush point. This means they'll hide
in or come flying around a strategically located tree or building and surprise the martins
and before they have time to react, one sometimes ends up in the predator's
talons. This is why our housing has to be located at least 60' from any
nearby tall trees.
Owls are located everywhere throughout the martin's range. Great Horned and Barred Owls (like the one shown here) will literally rip the housing apart if they can get at it. They are extremely strong birds, especially if there's a meal at stake. If you have some form of house, then there are guards that can be installed that will prevent these birds from gaining access to your housing. Some of these can be purchased if you have a standard aluminum house. If you have a custom house, then you may have to custom build one for your particular housing requirements. These can be built using a standard 4" page wire that can be purchased at any farm supply store.
Here is a picture from Danny Frazier's site in Oklahoma showing owl guards mounted
to his martin houses. As you can see, the martins are very adaptive birds. Once
they get used to the guards, they don't pay them any attention at all. In fact,
they even use them to rest in.
If you have gourds as your housing, they too, can be protected. Owls attack by normally landing on the rack and listening for noise coming from inside the gourds. Martins make a lot of noise at night and owls can hear this. Once the prey is located, they fly down and hover in front of the selected gourd, reaching out to grab the entrance hole with one claw, (thus, the reason for finding claw marks on the front of martin housing). They then use their wings to beat on the sides of the gourds, (and thus, the reason for finding owl feathers on the ground after an attack), spooking the martins to take flight. When a martin tries to exit the gourd, the owl snatches it with the other claw and then flies off to feed. Once successful, they'll return time and time again until all the martins are gone.
It was once thought that gourds that swung freely would help do a number of things such as prevent starlings from nesting in them, but that statement has absolutely no merit. Likewise, the swinging of a gourd does absolutely nothing to prevent an owl attack. My gourds swing freely and before I had owl guards, I was attacked numerous times by owls at different times. However; if an owl is unsuccessful after a couple of attempts, they will usually fly off and look elsewhere for easier prey which is what happened at my site. Owls will not waste precious energy on failed attempts at getting food, they will usually simply move on to easier pickings. So it's up to you as a landlord to make things as difficult for any predator to get at your martin housing. The more difficult, the harder it is for them to get at the housing and the safer your martins are.
So, what can be done to prevent owl attacks. First, an owl has to be prevented from hovering and gaining access to the gourds. If they can't hover in front of or reach out and grab the gourd, then they can't get at the martins.
Again, the page wire can be utilized to make a baffle of sorts (umbrella style) where the martins can slip through, but the owls can't.
A second option is to attach aluminum rods to the rack arms and then bend them in a curved shape down in front of the gourds, keeping them about 15" to 18" in front of the gourds. The idea is to prevent the owl from hovering in front of the gourd by getting in the way, thus preventing the owl from getting a foothold on your gourds.
And, although this hasn't really been tested, I use SREH's with porches and one thing about them is that they are very tight in size and a martin has to squeeze through them to begin with. If an owl grabs hold of a gourd by the SREH, it's claws fill up much of the hole, doing two things.
One, it prevents the martins from being able to exit the gourd thus, actually protecting the martin in its gourd;
And two, it prevents the owl from successfully getting at the martins. A Crescent entrance hole is too small for an owl to reach into with its large claws. Because of the fact that crescent SREH's are new and it's hard to predict when an owl will come to visit, it's hard to do research on this thought. But, I use crescents exclusively and I also know personally that owls have come to visit my site on numerous occasions and as per my records, I have yet to lose a martin to them.
Insect Pests and Parasites
Purple Martins are
bothered by a variety of insects and parasites. These parasites have to be
controlled if the parent birds are to raise large and healthy broods.
Again, where you live will determine the type of pest problems you'll have. We
won't try to discuss them all here, but we'll attempt to express what can be
done about the major ones.
Mites, Lice, Fleas and Blow flies (and ants in the south) are some of the major concerns most landlords
run into. These parasites live in the nesting material and feed on the young.
Most of these can be controlled with diligent nest checks. When found, they need
to be tended to.
Mites, Lice:
Mites are small parasites that stay in the nesting material in the nest and live
off the young. They are usually brought into the nest by the parent birds when
the go to the ground to get nest building materials. They are found just about everywhere.
Lice usually live out their entire lives on the birds themselves.
Fleas:
Fleas are pretty much self explanatory. Everyone has run into them with their
family pets. Unfortunately, they are not as easy to control on and around birds
as they are on cats and dogs.
Blow fly larvae:
Blow fly larvae can become a problem around hatching time in the northern
latitudes of the martin's range. Blow flies lay their
eggs in the nesting material and when they hatch, they survive by sucking the
blood from the young.
Controlling them:
First let me say this...
NEVER use ANY kind of 'insecticide' from a 'spray' can and spray into a bird's nest to rid
it of fleas.
It is a poison, will fill the cavity with fumes and could harm the young.
Diatomaceous Earth: (Per original thinking and still advocated on some
sites).
I've tried DE and unfortunately, I found it to be useless. It just didn't work and in fact, makes a mess once it gets damp or wet. Although I find it a waste of time, if you want to know how to use it, here's the scoop.
What is recommended is to sprinkle it around the outside edge and under the nesting material about 10 days after the young have hatched and again about 10 days later, keeping it away from the center of the nest so the birds won't peck at it and ingest it. If you want to try it along with nest replacements, Diatomaceous Earth can be found at most garden centers and Co-ops, and is supposed to work by breaking down the exo-skeletons of the insects allowing them to dehydrate. It's also recommended that nest changes be done along with it's use, but I've also found that the nest changes alone do the same thing.
A Diatomaceous update note:
Recently it was discovered that DE is a possible carcinogen and is NO LONGER RECOMMENDED to be used in martin nests by many of the major martins 'experts'.
Nest replacement. If you plan to treat your pests by replacing the
infected materials, here is how it's done.
Make a small temporary nest in a
small box or bucket. Use dried lawn clippings for the nesting material. They're
soft and won't harm the young birds. Place the young in this temporary nest. Now
remove all the infested nesting material from the nesting compartment.
After doing so, it is recommended to wipe down the compartment with alcohol.
The fumes will quickly dissipate. Replace it with new material, making a 'bowl' as close to the original place as
possible. Make
sure there is enough material to separate the young from the compartment floor.
Now, simply replace the young and close up the compartment. Burn or bag
the old material to remove the pests...period...
Replacement materials can consist of wheat straw or pine straw, (pine needles).
Grass clippings are not good because they retain water too easily. Doing nest replacements will also teach your birds to trust
you. The young will learn to accept being handled and will fear man less than
birds that are not tended to on a regular basis. This is one major reason
that you need to be able to easily get at your housing. And, if your housing
does not facilitate easy nest replacement, it should be reworked so that it can
be done. Remember, this is a hobby, and it is supposed to be fun, but you are
working with live creatures, and you need to be able to do whatever is required
to protect them.
Sevin Dust, Sulfur; Etc;
Authors Note:
There is much controversy on the use of this pesticide to control insect pests in the nests of purple martins, therefore, I will not "tell you" to use any pesticide of any kind, especially anything from a spray can. Improper use could result in harming your birds. As of this writing, there is no approved method in print, (that I know of other than here) from an approved source that talks about using any pesticide use.
However; I will tell you "what I do" and if you want to try that then fine, but I will not be responsible for someone's mis-use of a chemical and harming their birds.
What I do not do:
I do not use Sulfur! Sulfur is caustic and can burn a young birds skin and eyes.
I do not use Cedar Shavings! They have been proven not to control insect pests and they absorb water, thus keeping the nest wet.
I do not use any kind of chemicals out of a spray can! They are much too uncontrollable and most will harm young birds.
What I do:
When mites infest my colony, I do this. I take less than a level teaspoon of 5% Sevin Dust and sprinkle it on the nesting material, just inside the entrance hole. Mites travel in and out of the nest by way of the nesting material and in doing so, they pass through the Sevin dust and when this happens, the Sevin gets on them and kills them.
Secondly, the parent birds will spread the Sevin around the front of the cavity by their entering and exiting the cavity. Usually, the treatment eliminates the mites within 24 hours and only one treatment a year is required. Plus the parasites on the host birds are also killed, removing a threat of their 'restarting' to build in the nest again. As with any chemical, more is not better. Only a very little is required. Give it time to work the way it was intended. Sevin was formulated to work in the poultry industry just for this reason, to rid the poultry of chicken mites, but it takes about 24 hours to work, so once applied, be patient.
Ants/Fire Ants:
Ants have been around for eons, and are part of a landlords nightmares if
plagued by them, especially the fire ants. This is a new predator that is
becoming a real problem in the Southern part of the purple martins' range. They
will climb the pole and kill the young by feeding on them. Once found by a
foraging ant, the young are doomed, and stop to think of what kind of death this
is for the young that are totally helpless to defend themselves. The ant leaves
a chemical trail that all the other ants can follow and soon the young are
totally destroyed by the ants.
There are a few things that can be done. Petroleum jelly can be added to the
pole and it will effectively repel the fire ants for as long as it lasts, but
the ants have to be dealt with as soon as possible. As soon as the jelly is
gone, the ants will be up the pole and at the young.
One treatment that works is to break open the top of the hill and then sprinkle some
Orthene, (Acephate) on the mound getting some on some of the ants. Ants are
very meticulous and will clean each other off. This chemical works very
well and will usually kill the hill within 10 to 12 hours. Also,
sprinkling some in their paths will also eliminate the colony. Some gets
back to the queen and when she dies, so does the colony. BE CAREFUL!
This is serious stuff. Read the directions for use.
What I've tried to do here is give you a basis to work with for protecting your
martins. Depending on where you live, I'm sure there are probably other types of
predators and parasites that could do damage to your martin site and depending
on your predator problems, you may even have to come up with another type of
solution. If so, give the situation some thought as to how to solve your
particular problem, then go for it. Remember, 'necessity is the mother of
invention'. Just make sure that whatever you do will 'protect' your birds and
not 'harm' them or any of your children or pets. If it's a poison, then use it
intelligently and don't overdo it.