Progne subis
The
Purple Martin is considered to be America's most wanted bird.
The interaction between man and martin dates all the way back to the
Native Americans and continues to this day. With its bubbly personality
and gurgling song, the purple martin is cherished by all that host them and each spring brings
on an excitement that only a purple martin landlord (someone that keeps martins)
can experience as they
anxiously anticipate the return of their beloved purple martins.
For
some people acquiring martins can be very easy, while for others, very
exasperating. For those that are interested, the following overview is intended
to help educate potentially new landlords with what it
takes to attract, keep, protect and properly care for a colony of purple
martins. It's also intended to bring experienced landlords up to date with all the new discoveries in the last two decades
about martins. With all the new findings from studies and testing, hosting purple
martins has become a lot more than just sticking a house on a pole and letting
the birds do their thing. There is a right way and a wrong way and hopefully
some of the differences between the two can be explained here.
Myths abound about these beautiful birds and maybe while we're at
it, we can dispel a few of
those, too.
Purple martins are the largest member of the swallow family in North America with the adults being typically 7 - 8 inches long and having a wingspan of approximately 12 inches. The mature adult male's entire body color is a blue-black, except for a very few white feathers usually 'hidden' directly under the wings next to the body. Females and sub-adult males, on the other hand, look a little different. They are dark on the back with gray undersides. The females will never attain the full black body dress, always having a gray mottled chest and belly. However, the sub-adult males will get their full body of black feathers in their third year of life. This delaying of achieving their black feathers is called delayed plumage maturation.
The gurgling and chortling sounds of purple martins are not only very distinctive, but also very pleasant to listen to. Upon their arrival to their nesting sites in the spring, their call is immediately recognized by landlords (people that keep martins) and it usually brings an excitement that can only be understood by those having a martin colony.
Purple martins have a normal lifespan of about 5 to 7 years and it's not out of the norm for them to reach 9 or 10 years of age. Banding studies have shown them to reach many more years than that, but those are the exception. Because of the long distances they have to fly during migration, the death rate for martins is high. Population studies have shown a decline of birds in some areas due to habitat lose. This is one more reason we humans need to help this beautiful native bird species by supplying them ‘proper’ housing in which to raise their young. Being native to this country, these birds are also protected and therefore, they or their nests may not be harmed in any way.
Martins are neo-tropic in nature, (migrate south each year). They nest 'exclusively' here in the North American hemisphere and then after nesting is complete, migrate to South America (Brazil, Argentina and surrounding areas) each fall where they spend the winter months molting and gaining a new set of feathers. There are considered 3 main flyways that martins use. The Baja, (through the eastern edge of Mexico), the Louisiana (over the Gulf of Mexico) and the Florida Keys, (up the Keys and east coast). Purple martins migrate well into Canada each year with a few spots still having good populations. Scouts begin arriving in the U.S. in January in the southern region and birds continue arriving well into May, even June in some of the more northern latitudes. Many people don’t consider it spring until the martins have arrived.
There are three basic factions of birds that need to be considered.
First, there are the HY (Hatching Year) birds. These are birds that are born during the season and are also known as 'fledglings' and have not made their first migration south yet. When fledglings leave the nest to fly south for the winter, on their return the following spring, they do not usually return to their natal site (the site where they were born). Having never nested before, they do not yet have the 'site fidelity' that the older birds have and will look for a site to nest where ever they can. It's these birds that will be returning as SY's. Usually, only about 15% to 20% will return to their natal site. Instead, these SY birds will usually look for a new site to set up housekeeping. This is nature's way of preventing inbreeding. Banding studies have shown that SY birds have been spotted as far as 200 miles away from their natal site.
Next, there are the SY (Second Year) birds. As stated, these are the birds that were born the previous summer, made one trip south and are now returning for the first time to nest. These are considered the teenagers of the martin world. They will be sporting the plumage of sub adults and at this stage, both sexes look somewhat alike. The males will usually have a darker throat patch, a darker head cap and often, occasional blue-black feathers spotted here and there on the chest. Although not always, these are the birds that usually start new colonies because they haven’t nested anywhere else before and thus, don't yet have the site tenacity that the older birds obtain from nesting. These SY birds typically arrive about 4 weeks behind the ASY birds.
Lastly, there are ASY (After Second Year) birds. These are the adult birds that have been through a year of nesting and are returning north for at least a second time. It's these birds, (usually the all black males) that people identify with as Purple Martins. These birds are at least into their third summer of life and are usually the first birds to return each year and will be in their full adult plumage. These are the birds that will first arrive in the spring to their nesting sites and it's these first birds to return that are usually considered scouts.
Because of the nature of these first birds to return to a site and then disappear for a time, it was thought that these 'scouts' would return south to get the rest of the flock. This is a long time myth. These early arrivals do not go back to get the rest of the flock. It's much too early for them to begin nesting, so they simply spend their time getting to know the area again, just being wild birds and spending their time in trees or on power lines, waiting for more birds to return. These first birds are usually the older and more experienced birds and know that the earlier they return to their site, the better chance they have of getting the best nesting compartments in a site.
As stated, purple martins nest exclusively here in North America and Canada and rear only one brood of young per year. (Second broods have been reported, but this is the exception). Their eggs are pure white and are laid shortly after nest completion. Nest building begins shortly after a pair has selected a home site and cavity. Normally, the males select the cavities and then begin attracting females. The females usually select a mate, not because of him, but because of the cavity he has selected which is why there might be fighting over the best cavities in a site. Often, the same male and female will pair up again if they had breeding success from the previous year and they both survive the migration. Both begin the nest but the female usually puts the final touches to it, finishing it to her liking. Because of the difference in latitudes, nesting dates may vary greatly as to the timing, earlier in the south and progressively later in the north.
Just before egg laying begins, both birds bring in green leaves to line the nest. Some nests will have an abundance of green leaves while others will only have a few. Although not exactly known why, it’s thought that these are used to keep the eggs moist and possibly keeping parasites away. When the female leaves the nest to feed, she will often cover the eggs with these leaves. Only the female has a brood patch (a patch of bare skin she develops on her chest to incubate the eggs and which she keeps hidden under her chest feathers). Once eggs are laid, the female does most of the incubating however; the male will occasionally relieve her for short spells. Incubating officially begins when the 'next to the last' (pippin) egg is laid. Approximately 16 days after incubating begins, the young will hatch. From this point on, both parents will feed the young with the average time from hatching to fledging being about 28- 32 days. After the young have fledged, they will be fed for a few more days until the parents teach them to catch their own food. The young often return to the hatching site for about a week, but will eventually leave permanently to join the adults, returning only occasionally. It's about this time that the parent-fledgling bond is broken and the fledglings are now totally on their own. When fledging is complete, both adults and fledglings often form large pre-migratory roosts in many areas of the country, preparing to make the trip south. Although not always, these roosts are usually formed around a large body of water or near man-made structures such as bridges or power antennas. Some are even formed in trees surrounding large mall parking lots and can contain up 100 thousand birds. These roosts usually last for about a month, then one day something inside their biological clock goes off, and so do they, beginning the migration back to South America. The older birds will leave first and the departing progresses to the younger birds leaving last
Purple martins are found just about everywhere in North America with the exception of the Rocky Mountain States and are identified by three different species. The two western species are a little different than the eastern because of their different nesting habits. In the deserts of the southwest, they still nest in the wild using available holes in trees and cacti. The northwestern variety also uses some trees along with individual nest boxes supplied by landlords on high poles. However, here in the eastern U. S. and Canada, they have become totally dependent on humans to supply them housing for nesting.
Martins
are extremely good flyers, averaging about 17-27 miles an hour and obtaining
even faster speeds of around 40 if being chased by flying predators.
They have extremely well developed wings that seem to let them float on
air with little or no effort. These
wings have to be well developed in order to carry them from their southern
wintering grounds in South America to here in the U.S. and even all the way into Canada and then back each year.
Purple martins exclusively eat flying insects, taking them on the wing. Among the list of many are houseflies, moths butterflies of all kinds, grasshoppers and their favorite, dragonflies. However, one of the major myths about purple martins is that they consume thousands of mosquitoes every day. This myth has been proven false time and again on dietary studies of the stomach contents of martins, but this old myth still perpetuates to this day. This was (and unfortunately still is) an early marketing gimmick used by some commercial house manufacturers to sell their products and it just isn’t true. Yes, martins do eat thousands of insects, but testing has proven that less than 2 - 3% of them are mosquitoes. This is not to say they don't eat mosquitoes, but the quantities are so low that they would hardly clean out all the mosquitoes around anybody's yard.
If a person would just stop and think for a minute, they would figure it out on their own.
When do mosquitoes become most prevalent to do their biting… about dark… and when do most birds, (including purple martins) go to bed… about dark.
Mosquitoes hang out near low bushes and shrubbery… martins forage very high in the air… (as high as 300 feet).
Mosquitoes
are very small with low energy content… martins prefer larger prey.
The larger the prey, the more energy returned for the energy spent in
catching it.
Martins do not usually forage close to their nesting site, but usually fly some distance away to obtain their food. Sometimes this could be a couple of miles.
The favorite food of purple martins is dragonflies and dragonflies are the mosquitoes ‘foremost’ predator. Dragonfly larva feed on the larva of mosquitoes, so in reality, it could be said that purple martins actually help the mosquitoes by eating their worst enemy.
Another myth is that martins will eat large quantities of Honeybees. This is also a falsehood. Martins may eat one or two of them but the majority of the bees they eat are the drones, simply because they are the only ones that fly that high looking for queens to breed. Normally, worker honeybees, (the females) stay much closer to the ground and don't usually cross paths with feeding martins. Secondly, the female honeybees have barbed stingers, and if not killed instantly, these stingers could find an occasional soft mouth part. Drones do not have stingers and thus make a less dangerous target.
Martins will forage for food when the temperature climbs above 45 degrees. They will also eat eggshells and oyster shells when supplied by the landlord, which provide them with calcium for stronger eggshells. They also feed them to the young as grit to help digest their food. These can be supplied on a small raised platform set on top of a 4 or 5 foot high post. They will quickly find them and don’t be surprised if large quantities are consumed during a nesting season.
Martins will not eat from a bird feeder nor will they typically land and drink from a birdbath (although they have been known to use a large swimming pool). As with all the swallow family, they eat, drink and bathe on the wing and a source of good clean fresh water is a major advantage in attracting them to your home. This could be a small fresh water pond or an open nearby stream. However, if not readily available, they have been known to fly up to 1 or 2 miles for water. Martins are a very clean bird taking their fledglings’ excrement, and their own, a good distance away from the nesting site. This is done to prevent the draw of unwanted predators to the area.
Purple
martins are very friendly towards humans. If
enough time is spent around their sites, they soon begin to accept the landlord
as part of the site and will soon ignore his or her being there entirely.
In fact, it is well documented that the more human activity there is near
a martin site, the more martins will show up.
They are not the least bit afraid of man or his modern technologies or
innovations (a term I like to call 'technovations') and
in fact, they actually seek out sites where there is abundant human activity.
Through generations of imprinting, martins have learned that
where there are humans, there often aren’t any predators.
If worked with close enough, purple martins can almost be ‘tamed’ and
getting young children interested in them is also a big plus.
There is no age limit on hosting and enjoying martins and if taught
properly from an early age, children become very interested in and quickly learn
to respect them and there is nothing better than teaching the young to respect
nature. And as the colony grows,
watching their aerial acrobatics is a joy in itself and a source of amusement
and amazement
for all that take the time to enjoy them.
Housing:
As stated, purple martins in the eastern portion of the country are now totally dependent on man made housing. Originally, Native Americans discovered that, if they put up hollowed out gourds, martins would use them for nesting. How this was discovered nobody really knows for sure, but they soon noticed that these martins would drive away some pests and predators such as crows and hawks. They also discovered that the martins consumed large quantities of pesky flying insects thus; the more gourds they put up, the more martins came and the fewer insects were around. Before long the martins learned to move from the trees to the gourds and around humans. The term for this changing of behavior is scientifically known as behavioral pattern shifting, a move which became mutually beneficial for both man and martins.
Today, many different varieties of housing are available. Many variations of wood, plastic and metal houses, natural and plastic gourds are all used and with today’s mass production capabilities, many new and different types of modern martin houses are available commercially. Unfortunately many of the standards for them are improper and many of these houses are inadequate for martins. In many cases the house compartments are much too small and some of the materials used are much too flimsy. A Great Horned or Barred owl with hungry young to feed will quickly rip the fronts off some of these houses to get at the young and adults inside. Many of these houses are not designed to allow for proper care and maintenance of the house. On some the front panels are not removable and cleaning out old nests or pest bird nests is next to impossible. In fact, some of these houses shouldn’t even be on the market, but because there are no standards for the production of martin housing, just about anybody will try and sell something to make money, regardless of how inadequate it is. And what’s worse, many 'unknowing' humans only look at some of them ergonomically and often purchase them just because they’re cute, when in reality, many of them are terrible houses in which to raise young martins. However, recently 'responsible' commercial housing manufacturers are beginning to realize this and are making the changes to their products so that the best interests of the martins are being considered and not just their bottom lines. These manufacturers are realizing that if the birds can't nest safely in their houses and they don't sell, then they might soon be out of business.
Because martins are now totally dependent on housing supplied by man, it is imperative that a set of proper standards be developed for these structures if they are to be used for nesting birds. With all the research and testing that's been done of late on this bird species, it's now easy to ascertain what is good and what is not for the purple martin as a nester in your site. All housing used for purple martins, regardless of materials and whether it’s commercial or home made, should have a few minimum standard requirements.
Here are a few starters:
All housing should be easily accessible for maintenance and nest checks. It should be able to easily be raised and lowered vertically on the pole. No housing that tips should ever be used, nor should houses that are hard-mounted to the top of a pole. These forms of housing are archaic in nature and should be updated to modern standards. Plus the use of ladders for maintenance brings up safety issues for the humans involved.
Nesting compartments should be a minimum of 6” wide x 5 1/2” high x 9” deep and up to 12" is even better. Anything less is too small for martins to properly raise a brood of young and back well out of the reach of talons of flying predators that often happen by looking for a meal. Houses that do not come with these dimensions or have the capability to change to them should not be purchased or used.
Housing should be painted white to reflect the rays of the sun thus, keeping the house cooler. Research shows that unpainted or dark colored housing, including gourds, are a full 10 - 15 degrees hotter than those painted white. The heat factor is often the cause of young jumping from the nest early on hot days, seeking relief from the heat
Easy access into the compartments via hinging or removable panels is imperative. The landlord needs to be able to easily get into them to clean out old nests, remove unwanted pest bird nests, perform nest checks and do general maintenance on the housing.
The
house should have good ventilation. This is an absolute must. A
couple of ½” diameter holes placed high in the front and rear walls of
the compartments allows for air flow through the compartments and the young
birds will need this, especially in the southern regions of their range.
This one simple feature in housing greatly improves the chances of the young
making it through the hot spells of summer. 
Because of the introduction of European Starlings into this country, all housing should contain SREH’s, (Starling Resistant Entrance Holes) of some form. There are a number of different styles available, but the crescent option shown here is the easiest to make for the average landlord. The new 1 3/16” high crescents have proven to effectively keep 99% of all starlings out of martin housing while at the same time, allowing martins easy access. However, in order for them to work, the height dimension of 1 3/16" is critical. Round holes are no longer the ‘standard’ and any information you read about using them is now ‘outdated’. The drawing shows the dimensions for the new crescents and they can easily be cut with a jigsaw and a small wood rasp for accuracy. Also, it has been discovered that the material these SREH's are cut into should be no more than 1/4 inch thick. More than that and the martins have too much difficulty getting in. Also, recent testing information has also shown that any SREH should have porches, both outside and inside the compartment. These porches should be a minimum of 3" x 3" and located between flush and 1/8 inch below the bottom of the crescent opening. The reason is that this helps the martins to negotiate these tighter openings, while at the same time, making it much harder for the long legged European Starling, to get in.
Housing Location:
Once it's decided that you'd like to start a purple martin colony, the first (and probably the most important) thing to look at is the location of the housing. Martins do not like trees close to their nesting sites therefore, if the selected site is heavily wooded, then your chances of attracting martins is very low. Martins just won't come to sites where trees are prevalent. They need very open and unobstructed flight paths to get to their housing and if this is not available, then it should not be considered martin territory.
Martin housing should be located as far away from any nearby obstruction as the obstruction is tall. For instance, a general rule is, if you have a 60 foot tall tree in your yard then a good starting distance from the tree for the housing would be 60 feet or more. Tall trees harbor ambushing predators such as hawks that feed on martins and having trees taller than the housing in close proximity will afford those predators cover and dropping out of the higher limbs allows them a head start on surprising and ambushing the martins. Martins are aware of this and therefore, stay away from such situations. The more open the selected site is, the better the chances of attracting them. The same applies for any bushes close to the base of the pole. They too, harbor climbing predators and martins shy away from such sites.
However, as goes against all rules of nature, martins actually like to be close to human housing. As stated earlier, martins like to have human activity near their housing and in fact, often pick the nest cavities that face the human housing. Yes, when they first arrive to a site, they will fly off if approached too closely, but within a short time, they get used to the humans and will soon sit right on their housing and not even pay any attention. I personally will go out of my way to walk near my site just so that the birds will get used to me. The more time spent around them, the quicker they get used to the human activity and they soon begin to ignore it all.
Nesting Competitors and Their Control:
The two worst problems for martins today are the European Starling and the English House Sparrow. Both of these species were introduced into the U. S. in the 1800’s and have propagated to the point that they are extreme pests today and not just for purple martins, but for humans as well. Both of these introduced species have taken over many of our own native cavity nesting birds’ homes, leaving them with no places to nest and raise their young. Both are the martins’ worst enemies and both will usurp the martins’ nesting cavities and then vigorously fight the martins off to defend it. Once obtained, they will fill the cavity with nesting material so that the martins will never go into the cavity again. In many cases the original martin tenants will be evicted and the young or eggs destroyed. Often, if a starling can trap an adult martin in its cavity, it will attempt to kill it and often succeeding. The starling will then begin building a nest right over the dead bodies as if they weren’t even there. People that allow either of these two species to nest in their martin housing and then believe that the two species are living in harmony are not very well educated about their birds and are ‘only fooling themselves’. Studies have shown that once starlings or sparrows are allowed to nest in a martin house, the existing colony declines, and soon disappears.
Sparrows are especially difficult to control because one; they are small enough to negotiate any size hole that the martin can get in and two; once they fill one nest cavity with nesting material, they will then proceed to the next and fill it with nesting materials and so on around the housing until the martins are evicted. Plus, they are notorious for 'pinning' (poking holes in) the eggs in the unguarded nests, thus rendering those eggs useless and since martins only raise one brood per year, they often simply leave. If sparrows are nesting in a cavity of a purple martin house, it is certain that it is the English House Sparrow. Native 'sparrows' do not use cavities to nest in, preferring the open limbs of bushes and trees.
In order to maintain a purple martin colony, these two species must be controlled. Some of the means are baiting and trapping with food, using nest box traps and shooting. Trapping and relocating is not an option. They will immediately return to the nest site. Birds have very good homing abilities. Anyone that is not willing or unable to control these two pest birds should not attempt to host a purple martin colony. These pest birds do not live in harmony with any other bird species and the problem with them is quickly becoming epidemic. In many areas where these two pest birds are heavily concentrated and not controlled, the purple martin population is on the ‘decline’.
Management, Doing Nest Checks and Getting Involved:
It is a misconception by many people that purple martins don’t need any help during their nesting cycle. They simply put the housing up and then let nature take its course. Unfortunately, this thinking is very wrong. Usually in these cases, the first thing to happen once the housing goes up is the pest birds will take over the housing. Next, these pests vigorously defend it to keep the martins out. If martins are already there, then they drive the martins off and usurp their cavities. From this point on, the only thing the well intended person has done is to propagate the very birds that are destroying the purple martin species.
Get Involved:
It is highly recommended by many experts that, we as landlords, get involved with our birds and become aware of what’s going on with them. The following are a few tips to help, not only for the beginner, but also the well-seasoned (but passive) landlord alike. Learn to get involved. Do not be afraid that you will drive your birds off. Watch the things that are going on in your colony and make sure you understand them.
Insure all housing is easily accessible by raising and lowering vertically. This can utilize a rope and pulley or winch and cable system that allows the housing to slide vertically up and down the pole for easy access.
Learn to do nest checks. Learn what to look for, what to do about it and how to keep records. And remember these following things;
-NO, martins will not abandon their nests simply because you lowered
their housing.
-NO, it will not bother martins if you temporarily invade their nest to
check things out.
-NO, martins can’t smell your hands wherever you touched.
-NO, martins will not abandon the chicks because you touched them.
All of the above are myths passed down through time from uneducated landlords.
Check for insect pest infestation. Mites and blowflies are sometimes a major problem around martin sites. Learn how to identify them and what to do about them. A large infestation of mites or blowflies will easily kill young martin chicks or drive them prematurely from the nest.
NOTE: The use of pesticides in a wild birds nest is a very controversial subject. This article is not to concur nor condemn its use, but to offer an option that is available should one wish to use it.
There are two things that will work against these two insect pests. A half teaspoon (level) of 5% Sevin dust 'sprinkled' on the nesting material only just inside the entrance hole will usually control even the worst case of mites, usually within 24 hours. However, blowfly larva do not seem to be deterred at all by this material and to this date, only nest changes have shown to be affective against this pest. Usually blow flies are only a problem in the northern reaches of the martins range. Diatomaceous Earth (DE) was once used and promoted by some experts, but that thinking has since changed. Tests have shown that it does no good to use DE in a martin nest for parasite control, and although some folks still think it works, personal experience has found it to be quite useless.
And please note: Never use
'spray' insecticides of any kind in a wild bird's nest. These sprays are
very uncontrollable and the dispersing agents can cause harm to the birds.
If
the use of chemicals is not to your liking, then a
second thing that can be done is to totally change out the affected nests once
or twice during the season. This has been determined the best method for
controlling blowfly larva. To do a nest change, place the young in a
temporary box with tissue paper in it. Then the old material should be removed
and burned. This gets rid of any hatching larvae. The compartment can then be swabbed down with rubbing alcohol
to kill any remaining mites or blow fly larva. New nesting material can now be added.
Try using the same type of material
originally used by the martins matching the original nest as close as possible
with the depression in much the same place. Nestlings are then gently replaced
in the nest.
This activity should be done quickly and only on warmer days so the nestlings
won't be chilled. The entire time the nest-change is taking place there is a
very good chance that the landlord will be subjected to a lot of martin fussing
and dive-bombing (strafing), but don’t worry about it. The adults will get
used to you being there and soon light somewhere close by and watch until you
complete your task.
·
Learn
what to do about land based and flying predators.
Any of them can wipe out a colony if the proper precautions aren’t
taken.
·
Learn
how to make your present housing desirable, to enlarge the compartments so they
are able to back out of the way of some predators.
·
Learn
how to defend the house from other flying pests such as starlings and sparrows
and what to do to keep them out.
One
good thing to do in new housing (and used housing where the old nesting
materials have been removed) is supply the compartments with a pre-made bed of nesting
material, especially if the floors are 'slick'. Martins seem to enjoy this and readily accept these compartments
over others that are empty. An ample amount of pine straw (dried pine needles) or wheat straw added
to the cavity makes the martins much more interested in it. Add
enough to bring the material right up to the bottom of the entrance hole
or internal porch if you are using SREH entrance holes.
Purple martins have very short legs and this helps greatly in the exiting of the
house compartment or gourd. Both pine and wheat straw are available at just
about any garden shop or co-op and are rather inexpensive. Sawdust or
shavings of any kind are not a good base for a nest because they're not stable
under foot, especially on slick surfaces such as plastic or aluminum and will soak up water, leaving the nest wet.
Often the martins will discard these in favor of more stable materials.
Extra nesting materials can be offered, either on a raised platform made just for it, or simply spread out on the ground, (assuming there are no predators around). A simple 2' x 2' square platform, placed on top of a 4 or 5 foot tall post near the housing and filled with wheat or pine straw will soon become the primary source for their nesting material. The martins will use it to 'top' off their nests to their liking.
Friendly Competitors:
Martins
also have 'friendly' native nesting competitors, but these competitors should be dealt
with differently. The basic ones most people will have problems with are
bluebirds and tree swallows. These are native cavity nesters and also have to
compete with the starlings and sparrows for nesting sites. However, these birds
should not be harmed in any way. These are native birds and all our native
bird species are protected. If one decides to nest in your martin housing then
the appropriate single-unit housing for them should be erected 50 to 100 feet or
so away. Then, close all the holes in the martin house until the suspect bird finds
the new housing and sets up housekeeping. After this is accomplished, the martin
housing can then be re-opened.
Predators
All
sorts of predators try to get at the martins and their nests and all housing
should be fitted with the proper predator guards. Ground predators include,
among others, raccoons, snakes, squirrels, cats, and are the easiest to
guard against. There are many different designs of pole guards and available
information on these should be researched for the proper guards. A simple tube
guard, ten inches or more in diameter and 3' long mounted to the pole will stop
most ground predation attempts. Another type of effective ground predation guard
is a metal collar approximately 3' in diameter and built in the form of a cone
or Chinese hat. Loosely mounting these guards at a height of around 5' or higher
will work very well to protect your martins.
At
one time or another, Accipiter hawks will discover your colony, but since they
are protected, there really isn't anything that can legally be done about them
other than to be present around the colony as much as possible. Unlike
martins, they don't like the close proximity of humans and will often shy
away. This is why open
flight paths are necessary around martin housing, making it more difficult for
these raptors to launch their attacks. Fledglings and immature adults are
usually the ones that fall first. An adult bird, by its sheer energy and
spectacular flying abilities can, and usually do, out-maneuver and out-fly these
predators.
Owls
can be of particular concern. Owls usually come out at dusk and do the majority
of their feeding at night when most landlords are asleep. Unless a colony is
closely monitored a landlord might not detect that an owl is preying on the
colony and it only takes a few nights for an owl to do its damage. As long
as it is successful, it will keep returning, night after night, until the colony
is totally wiped out. In the case of gourds, an owl will land on the rack arms and sit and listen to
determine which gourds the birds are in. (Martins are very noisy at
night). Then it will drop down and hover in
front of the target gourd as it grabs on to the entry hole with one claw. It will then
beat the sides of it with it is wings, scaring the adult martins out into its
waiting claws. Owl predation on houses is similar and where owls are prevalent,
owl-guards are essential. Several designs are available, but the idea is to keep
the owl from hovering in front of the entrance hole and again, there are a
number of different designs available and the landlord should do a good amount
of research to find the one that will meet his or her needs.
Nest Checks in Detail:
Female Purple Martin on her nest
“Do nest checks”. In other words, martin housing should be monitored by the landlord. It is very important to know what’s going on in your colony, and one more thing, they are actually “fun” to do. Knowledge that something is wrong with the colony can't be detected in time to correct the problem without proper nest monitoring. "NO", as stated (and shown) above, you will NOT scare your martins away by doing nest checks. Contrary to some beliefs, martins will not mind if you temporarily invade their nests. Without proper monitoring the number of eggs, nestlings, and fledglings cannot be truly determined. Without monitoring there is no way to know if predation is happening. And although it is not actually necessary, it does help to keep good records. If a nestling falls out of its compartment, it can be replaced to the proper compartment if you have good records. If a nestling should die in the compartment it should be removed as soon as possible. No, the parents will not throw the dead baby out of the nest. Without monitoring, the dead fledgling will rot next to its siblings, creating a possible growing medium for insect pests. Eggs that are removed from the nest by the female should not be replaced in the nest, but instead, discarded. Only the female knows which eggs are viable and which are not and she will often remove unviable eggs from the nest and roll them towards the front of the compartment, but not having fingers, is unable to get them out of the cavity.
Nest
checks should be done every 4 or 5 days beginning with nest building and
continued until the oldest fledglings are about 22 to 24 days old.
After this
age, internal nest checks should cease. The reason, any sudden disturbance of the housing could make them jump and again,
this can only be known by doing detailed nest checks and keeping good, concise
records. Opening the compartment at this point might panic them into attempting
to fly and leave the nest, so for these last few days the housing should not be
bothered and the birds should be left undisturbed. However, continue to monitor
things from the ground. Daily walk-unders are a must. With good records and good
timing, a few days later you may be fortunate enough to get to witness the
maiden voyage of the newly designated fledglings.
When
all the birds are gone, the housing should be cleaned out and either taken down or
closed up until the next year. Leaving the housing open and accessible would
only encourage pest birds to roost in and claim ownership of them. At this time,
any repairs or modifications should be done to the housing and support pole in
preparation for the next season of returning purple martins. This is a very good
time to make that ‘non-accessible’ housing fully ‘accessible’. It makes
hosting a colony of purple martins much easier and of course, much more fun.
If
you have Internet access, here's a link that has much more detail than this
brief.
Chuck's Purple Martin Page (http://chuckspurplemartinpage.com)
Authors’
note:
Hosting
purple martins can be a very enjoyable and gratifying hobby. It can also
be a very exasperating and trying hobby. When we humans make the decision to put up housing
to attract birds to our back yards, it becomes our responsibility to do it properly so
that they continue to have a good and safe place to come home to. A lot has
changed in the martin hobby in recent years and it’s our responsibility as
landlords and caretakers of these beautiful birds to educate and inform
ourselves with the latest available information and maintain homes that are not
only suitable to nest in, but safe. If we humans want to continue to have purple
martins around in years to come, then it’s our obligation to make the
changes necessary to enable the purple martin to continue to propagate and be
part of our native bird species.
Might
I also add, if one is not willing nor able to intervene in the nesting attempts
of European Starlings and English House Sparrows in purple martin housing by eliminating
them, then they would be best served finding another hobby. These two pest
bird species are slowly eradicating our own native cavity nesting bird species
and must be controlled and since man intervened in the natural order of things
by bringing them here, then we must again intervene to correct the problem by
eliminating them.
Chuck
Abare
Footnote:
The
information given above about purple martins was compiled from a number of
different sources too numerous to mention here. It's intent is to
consolidate generally known information, the latest research data and my own personal
experience's into one
article and get the average purple martin enthusiast or potential purple martin
landlord curious enough to search out more information about them so that they
become educated about the species and both
the obstacles and pleasures they'll run into ' before' undertaking the
hosting of purple martins.