The
Purple Martin
Progne
subis
The Purple
Martin is America's most wanted bird. The interaction between man
and martin dates all the way back to the Native Americans. To this
day, the purple martin, with its bubbly personality and gurgling
song, is cherished by many that host them. Each spring brings
on an excitement that only a purple martin landlord 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, it's very
exasperating. For those that are interested, the following overview
is intended to help educate potentially new, as well as experienced
landlords with what it takes to attract, keep, protect and properly
care for a colony of purple martins. With all the new discoveries in
the last two decades, 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” long and having a wingspan of
approximately 12”. The
mature adult males entire body color is a blue-black, while the
females and sub-adult males are dark on the back with gray
undersides. The
gurgling and chortling sounds of purple martins are not only very
distinctive, but also very pleasant to listen
to.
Martins are
neo-tropic in nature, (migrate south each year). They nest exclusively here
in North America and then after nesting is complete, migrate to
South America 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 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.
Scouts, (the first birds back) begin arriving in the U.S. in
Jan, 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 ASY
(After Second Year) birds. These are the adult birds
that have been through a year of nesting and are returning for at
least a second time.
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.
Then, there are the SY (Second Year)
birds. These are the
birds that were born the previous summer and are now returning for
the first time. They
will be sporting the plumage of sub adults and both sexes look
somewhat alike. The
males will usually have a darker spotted throat, a darker head cap
and often, occasional 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. These SY birds typically
arrive about 4 weeks behind the ASY birds. A third faction
that might need mentioning are 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.
Purple martins
rear only one brood of young per year. Their eggs are pure white
and are laid shortly after nest completion. Nest building begins shortly
after a pair has selected a home site. Normally, the males select
the cavities and then begin attracting females. The females usually select
the male because of the cavity he has selected. 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 add to the
nest. It’s thought that
these are used to keep parasites away. Only the female has a brood
patch and once eggs are laid, she does most of the incubating,
however, the male will occasionally relieve her for short
spells. Approximately
16 days after brooding 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- 30 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. 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. Then, one day something
inside their biological clock goes off and so do they, beginning the
migration back to South America.
Purple martins
are found just about everywhere in North America with the exception
of the Rocky Mountain States.
The western species are a little different than the eastern
because of their different nesting habits. In the deserts, 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.
The average life
span for martins is between 5 and 7 years with a few making it
longer. The death rate
for martins is high and studies have shown a decline of birds in
some areas. This is one
more reason we need to help this beautiful native bird species by
supplying them ‘proper’ housing in which to raise their young.
These birds are also protected and therefore, may not be harmed in
any way.
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 Brazil all the way into
Canada and then back each year.
Purple martins
eat exclusively flying insects, taking them on the wing. Among the list of many are
houseflies, moths and 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. Unfortunately
this was (and still is) a 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 less than 2 - 3% of them are
mosquitoes. That same
advertising ploy is still used today to dupe the uneducated
public into purchasing their products. However, if the average
person would just stop and think for a minute, they would figure it
out on their own.
·
When do
mosquitoes come out… about dark… and when do most birds, (including
purple martins) go to bed… about dark.
·
Mosquitoes hang
out in low bushes and shrubbery… martins eat very high in the air…
(as high as 300 feet).
·
Mosquitoes are
very small… martins prefer larger prey. The larger the prey, the
more energy returned for the energy spent.
·
The favorite
food of purple martins is dragonflies and dragonflies are the
mosquitoes ‘foremost’ predator. Dragonflies 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.
Martins will
forage for food when the temperature climbs above 45 deg. They will also eat eggshells
and oyster shells, 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 drink from a birdbath. 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. They 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 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 conveniences and in fact, they actually
seek out sites where there is abundant human activity. Through generations of
imprinting, (scientifically known as behavioral pattern
shifting), martins have learned that where there are humans,
there 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 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. 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 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, a move which became mutually beneficial for both man and
martins.
Today, many
different varieties of housing are available. Wood, plastic and metal
houses, and natural and plastic gourds are all used. 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 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 many, the front panels
are not removable and cleaning out old nests or pest bird nests is
next to impossible.
Many of the plastic and lesser aluminum 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, we as 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 some
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, then they will 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 hobby 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. No housing that tips
should ever be used, nor should houses that are solid 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.
·
Nesting
compartments should be a minimum of 6” wide x 6” high x 10” deep and
12" is even better.
Anything less is too small for martins to properly
raise a brood of young and keep well out of the reach of talons of
flying predators should the need arise. 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, 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, 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).
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. Round holes are no longer
the ‘standard’ and any information you read about using them is
now ‘outdated’.
The drawing below shows the dimensions for the new crescents
and they can easily be cut with a jigsaw and a small wood rasp for
accuracy.
Housing
Location
Once it's
decided that you'd like to start a purple martin
colony, the first thing to look at is the location. Martins do not
like trees, 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, if you have a 60' tree in your yard then a good
starting distance from the tree for the housing would be 60+ feet.
Tall trees harbor predators such as hawks and having trees taller
than the housing in close proximity will afford those predators
cover, allowing 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 predators
and martins shy away from such sites.
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. 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. 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.
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 the first thing to happen once the housing goes up is
the pest birds will take over the housing. Next, they 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.
It is an
absolute must that we 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. 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.
There are two
things that will work against these two insect pests. A half teaspoon of 5% Sevin dust
sprinkled on the nesting material only will usually control
even the worst case of mites, however blowfly larva do not seem to
be deterred at all by this material. Diatomaceous Earth (DE)
was once used and promoted by some experts, and although some still
think it works, personal experience has found it to be be quite
useless for parasite control. And please note: Never
use any kind of spray insecticides in any kind of wild birds
nests. These sprays are very uncontrollable and can cause
harm to the birds.
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.
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. The
compartment can then be swabbed down with rubbing alcohol to kill
any remaining mites. New nesting material can now be
added. Try using the same material originally used by the
martins matching the original nest as much as possible with the
depression in much the same place. Nestlings are then gently
replaced. 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 finish.
·
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 is supply the compartments with a pre-made bed of nesting
material. Martins seem to enjoy this and readily accept these
compartments over others that are empty. An ample amount of pine
straw or wheat straw added to the nest makes the martins much more
interested in it. Add enough
to bring the material right up to the bottom of the entrance
hole. Purple martins have very short legs and this helps greatly
in the exiting of the 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 aren’t
a good base for a nest because they're not stable under foot and
will soak up water, leaving the nest wet. Often, the martins will
discard these in favor of more stable materials. Martins
will often use small sticks in the building of their
nests.
Friendly
competitors
Martins also
have friendly native 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, etc, and
are the easiest to guard against. There are many different
designs of 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. 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 totally wipe it out. In the case of gourds, an
owl will land on the rack arms and sit and listen to determine which
gourd the birds are in. Then it will drop down and hover in front of
the 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
“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
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 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. Without monitoring, the dead
fledgling will rot next to its siblings, creating a possible growing
medium for insect pests.
Nest checks
should be done every 4 or 5 days beginning with nest building and
continued until the oldest fledglings are about 22 days old. After
this age, a 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.
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 is 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.
Here are a few
good books.
Stokes Purple
Martin Book, by Donald and
Lillian Stokes & Justin Brown
If you have
Internet access, here are a few good Internet
links.
http://home.hiwaay.net/~yankee1
Back to Chuck's Purple Martin
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This page created
and maintained
by Chuck Abare
Woodside Gardens
The Registry of Nature Habitats
Copyright 1999 -
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