Ten Reasons Why People Fail to Attract Purple Martins

Modified from: Hill, III, J. R. 1990. Top 10 reasons why people fail to attract Purple Martins. Purple Martin Update 2(3):28-29.
Ten Reasons Why People Fail to
Attract Purple Martins
James R. Hill, III
Founder & Executive Director Emeritus
Purple Martin Conservation Association
301 Peninsula Dr., Suite 6
Erie, PA 16505
[email protected]
It is estimated that well over a million people in North America put up housing specifically trying to
attract nesting Purple Martins. Unfortunately, only a small fraction of these folks actually succeed in
getting them. Below is a list of the top ten reasons why so many people fail in their efforts. Your chances
of attracting Purple Martins will be greatly increased if you avoid making these common mistakes.
better. The more open
your yard, the better. If
your yard violates this 40foot rule, try mounting
the housing higher relative to the trees, moving
the martin housing to a
more open area, or, as a
last resort, cutting down
one or more of the trees.
James R. Hill, III
1. Placing your housing too close to tall
trees or in yards that
are too tree enclosed.
The single biggest reason people fail to attract
martins is that they place
their martin housing incorrectly within their
yards, or their yards are
inappropriate
martin
habitat to begin with.
The correct placement of martin housing is a real art. Besides
preferring their housing
to be placed within a
certain distance of human housing (see reason
#3 below), martins also
have very specific aerial
space requirements. The
air space immediately
surrounding their housing, at the height of the
housing, should be unobstructed (i.e., void of
trees) in at least a couple
of directions, so that they
can fly to and from their
housing in nearly level
flight. There should be
no trees taller than the
martin housing within 40
feet of it, preferably 60 or
more feet. In fact, the farther the martin housing
is placed from trees the
Purple Martins avoid nesting in housing that has tall bushes,
shrubs, or vines growing around the base of the pole, or has
vines growing up it. Such housing is much more accessible
to predators, such as cats, raccoons, snakes, and squirrels.
2. Allowing other bird
species to claim your
housing first. If any
other species of bird is
allowed to settle into a
martin house before martins at unestablished sites,
those houses will rarely
attract nesting martins.
This is because birds set
up territories around
their nest sites and defend them against other
birds. Should an English
House Sparrow, European Starling, Tree Swallow,
Eastern Bluebird, Great
Crested Flycatcher, or
House Finch, etc., lay first
claim to a martin house
that didn’t house breeding martins the previous
year, these nest-site competitors will aggressively
repel any martins that
might come searching for
nesting sites.
James R. Hill, III
Martins are easily repelled from entire houses at unof being occupied. This is because martins have “learned,”
established sites by the aggressive actions of nest-site comthrough natural selection, that the closer they nest to man,
petitors. Why? Because if a martin has never nested at a
the safer they are from their predators. There are at least
particular site before, it hasn’t developed site tenacity there.
two reasons for this increased safety near humans. First of
Without site tenacity, a martin is easily repelled by any speall, most martin predators (i.e., snakes, raccoons, opossums,
cies that got there first. In contrast, once a martin has nested
bobcats, hawks, crows, and owls), tend to shy away from the
successfully at a particular site, it rarely will be intimidated
areas immediately adjacent to human housing. Any marfrom reoccupying
tin that nests within
that site the folthis zone of human
lowing year by any
safety should have
bird.
a higher probability
To attract Purof successfully raisple Martins to uning its young. Secestablished
sites,
ondly, the closer a
prospective landmartin nests to the
lords
absolutely
watchful eyes of its
must not allow any
human host, the
other species to
greater its chance
claim the martin
the human will withousing first. Acness, and thus repel,
complishing this
attempted predator
requires repeated
attacks.
lowerings of the
For these reahouse for nest tearsons, placement of
outs*, and in the
martin housing way
case of the nonout in open fields,
native House Sparor next to isolated
row and European
ponds, rarely results
Starling, trapping
in successful marand/or shooting.
tin attraction. MarShould native bird
tin housing should
species try to take
be placed in the
over your empty
center of the most
martin
housing,
open spot available,
temporarily plug all
about 30-200 feet
the entrance holes
from human houswith paper cups or
ing. If your mardoor stops, then
tin housing hasn’t
put up single-unit
attracted nesting
housing elsewhere
martins and isn’t
on your property.
placed within 200
Once the native
feet of your house,
species has actry moving it closer.
If a martin hobbiest allows any other species of bird, like this European
cepted the new
Starling, to settle into martin housing before martins do at unestabhousing, re-open
4.Painting your
lished sites, those houses and gourds will be far less likely to attract
the martin houshousing a color
nesting martins. This is because most birds set up territories around
ing and hope the
other than white.
their nest sites and will defend them aggressively against other birds.
native species stays
Although martins
put. *Just remember, it is illegal to harm native species,
have been known to nest in houses and gourds painted othor throw out their nests once eggs are laid, or young have
er colors, white housing seems to attract them best. First of
hatched, so it is important that landlords be very vigilant
all, housing painted white reflects the heat of the sun best,
when trying to attract Purple Martins for the first time.
so martins choosing white housing lose fewer nestlings to
heat stress. Secondly, white highlights the darkness of the
3. Placing your housing too far away from human
entrance holes best, making the cavities more conspicuous
housing. Research has shown that martin housing placed
to cavity-hunting martins. Finally, white is believed to best
more than 200 feet from human housing has a lower chance
enhance the male martin’s courtship display. As a result of
all these advantages, natural selection (and/or behavioral
imprinting) seems to have favored the choice of white housing by Purple Martins. There are many examples of people
who failed to attract martins until they painted their housing white. Even redwood and cedar martin houses should
be painted white, as should natural gourds. Trim can be any
color. The inside of martin housing should be left unpainted.
tins begin returning to any given area about 4-5 weeks after
the “scouts.”
Opening a martin house too early (or leaving it open all
winter) just results in instant occupancy by nest-site competitors, a situation that often prevents martin colonization
at unestablished sites. Prospective martin landlords should
not open their housing until about four weeks after the first
martins are scheduled to return to
their area!
The
only exception to
this rule is if a landlord has neighbors
within about a mile
that have established colonies. In
this case, open the
housing just as
soon as your neighbors’ first birds
have
returned.
There is a slight
chance you might
lure some of their
adult birds away if
your site (or housing) is superior to
theirs, especially
if you supplement
your
attraction
efforts by broadcasting, over loudspeakers, Purple
Martin dawnsong
or daytime chatter
calls that are available on CDs for
purchase from the
Purple Martin Conservation Association.
James R. Hill, III
5.Opening
up
your housing too
early. Most ‘wouldbe’ martin landlords rush to get
their martin housing opened up so
as not to miss the
arrival of martin
“scouts” in their particular area. This is
4-5 weeks too early
for
unestablished
breeding
sites!
Contrary to popular folklore, “scouts”
are not looking for
new breeding sites
to lead their flocks
back to. “Scouts”
are nothing more
than the very first
martins to arrive or
pass through a given area on their way
back to their previous nesting sites.
The arrival of
migrating martins
at all locations is
a continual process spanning 8-10
weeks in the north6.Opening up
ern half of their
Most people rush into the hobby not realizing that to properly manage
your housing too
breeding range and
for martins, they’ll need housing that allows for easy raising and lowerlate, or not at all.
12-14 weeks in the
ing, and nest compartment access. Landlords need to vertically lower
In an effort to keep
southern half, with
their housing often (sometimes daily) to evict nest-site competitors and
undesirable birds
new arrivals coming
to check on martin nestlings. Housing mounted on stationary poles, like
out of their mardaily — the oldest
this one, or on poles that only tilt down can’t manage their colony sites.
tin housing, many
martins arriving first
‘would-be’ martin enthusiasts leave all their entrance holes
and the youngest ones last. Older martins rarely, if ever, can
plugged ‘until the martins come around.’ This is a disastrous
be attracted to breed at new locations. This is because marmistake at unestablished sites. Closed-up martin housing
tins have tremendous fidelity to the exact site where they
at sites that were unoccupied the previous breeding seabred the previous year. It is usually only subadult martins
son will never attract martins. The only way that martins
(i.e., last year’s fledglings) that can be attracted to breed at
recognize potential breeding sites is by seeing open enunestablished sites, because they’ve never bred anywhere
trance holes, or by seeing and hearing other martins there.
before and have developed no site fidelity. Subadult mar-
7.Allowing vines
and shrubs to grow
under your housing
or up the pole. Unoccupied martin housing
that has tall bushes
and shrubs around the
base of the pole, or
has vines growing up
the pole, will rarely, if
ever, attract breeding
martins. Martins tend
to avoid such housing
as it is much more accessible to predators,
such as cats, raccoons,
snakes, and squirrels.
The solution is simple,
remove the offending vines, bushes, or
shrubs. Since Purple
Martins also like to
swoop down from the
tops of their martin
housing as they become airborne, almost
scraping the ground,
it is important to keep
the ground cover in
that swoop zone free
of plant growth or
fencing.
Most successful martin housing
has mowed lawn surrounding the support
pole for a diameter of
at least 50-75 feet. If
you have to erect your
martin pole near a fence, it’s better if the fence is only 5-10
feet form the pole, rather than out in the swoop zone. Another reason to keep the ground mowed in this swoop zone
is that this is the area where the landlord needs to conduct
his or her daily walk-under. Once you get nesting martins,
you will want to make
a daily habit of walking under the martin
housing to look on the
ground for evidence of
what is going on in the
housing above. You
need to become a biological sleuth, a bird
detective. A mowed
lawn is best for revealing evidence. Things
you may find laying
on the grass are dead
martins, dropped nesting material, thrown
out eggs, hatched
eggshell hemispheres,
dropped insect prey,
prematurely-fledged
baby martins, owl
feathers, plucked martin feathers, or starved
and grounded adult
martins. Each of these
pieces of data mean
something important
to the hands-on martin enthusiast and appropriate and timely
actions taken.
James R. Hill, III
At unestablished sites, martins will not recognize, as potential
breeding sites, any martin housing with closed holes. A few
compartments should be left open on each side of the house.
In contrast, landlords that had breeding martins the previous year can leave their housing completely closed, if they
choose, until the martins return and land
on the housing. They
can do this because
Purple Martins exhibit
a very high level of
site fidelity; once they
have bred successfully
at a specific location,
the same individuals
return to breed there
year after year.
Here is an example of martin housing not built to proper specifications. These individual units have floor sizes smaller than the minimum 6” x 6” necessary for martin nesting and are also nailed shut,
preventing the landlord from conducting nest checks. Because the
walls of these units are made of thin 1/4” plywood, any nestlings being raised inside this house would get heat stressed in the summer
sun. Since the modular cluster doesn’t raise and lower on a pulley,
the entire pole unit has to be tipped down 90-degrees for nest clean
out. All of these design flaws are unfortunate because the person
who built this house obviously took great pride in his or her work
and probably invested over 50 hours of work in its construction.
Sadly, housing like this is little more than an attractive lawn ornament that ends up being harmful to Purple Martins because it inevitably turns into a breeding slum for House Sparrows and Starlings.
8.Erecting housing that is not really
‘built to specifications.’ Many of the
published plans for
martin housing, and
a few of the commercially-manufactured
houses, are made to
improper dimensions.
Even some plans published in major encyclopedias, popular
bird books, or by state
and federal wildlife
agencies are incorrect
or very outdated. If
you consult ten different sources, you’ll typi-
Louise Chambers
10. Buying or building housing that can’t easily be
managed. Most people rush into the hobby not realizing
that to properly manage for martins, they’ll need housing
that allows for easy raising and lowering, and nest compartment access. Landlords need to vertically lower their housing often (sometimes daily) to evict
nest-site competitors and (weekly)
to check on martin
nestlings. Housing
mounted on stationary poles, or poles
that tilt down, are no
longer practical, due
to the introduction
and proliferation of
the House Sparrow
and European Starling. These types
of poles should
be phased out by
those who currently
use them. Martin
housing should be
mounted on poles
that telescope up
and down, or raise
and lower with pulley and winch systems. If you have
such a system, don’t
be afraid to lower
your houses often
to check on your
martins — you’ll
actually raise more
martins if you know
exactly what’s going on. Such disturbance will not cause
9.Attaching guy
martins to abandon
wires to your houstheir nests or their
ing, or placing
James Hill standing next to an example of an excellent, highly-mancolony site. Number
housing too close
ageable, martin house system. It is modular and built of 3/4” wood,
the compartments
to wires. Martins
which offers a lot of insulation from both heat and cold. The entire
and keep written relove to perch on
unit raises and lowers vertically with a winch, cable, and pulleys. The
cords.
wires, but they tend
compartments have large 7” x 12” floor plans and are equipped with
to avoid housing
starling-resistant entrance holes. Slide-out nest trays and insertable
James R. Hill, III, is
that is attached to
sparrow traps are available. The front door panels open on hinges and
Founder and Execuwires or are placed
the gourds that are hung underneath have rain canopies and screw-off
tive Director Emeritus
within leaping disaccess lids. Everything is painted white to reflect the sun’s heat.
of the Purple Martin
tance of them. They
instinctively know that squirrels can crawl along these and
Conservation Association (PMCA). He has been
gain access to the house. Never attach wires to a martin
hosting Purple Martins continuously since 1981.
house, especially if they lead to trees, buildings, or to the
For more information on martins, please contact
ground. It’s OK to hang gourds from gourd arms using wires.
the PMCA at <www.purplemartin.org>.
cally find ten different recommendations. Part of the problem is that no one had ever scientifically tested the martin’s
exact nesting requirements and preferences until I founded
the Purple Martin Conservation Association in 1987 and began
conducting such research. Here is some of what I learned:
A martin house
must have compartments whose floor
dimensions measure
at least 6” x 6,” but
floors measuring 7”
x 12” are far superior. If your martin
house does not have
at least a 6” x 6” floor,
modify it by knocking out inner walls
and combining two
cavities into one. A
round entrance hole
should have a diameter in the range of
1-3/4” to 2-1/4,” but
many commerciallyavailable
gourds
and houses are now
being offered with
optional
starlingresistant entrance
holes (SREH), with
non-round shapes,
that keep out all but
the smallest of these
nest-site competitors. SREHs are also
available as add-on
plates or tunnels for
both houses and
gourds.