Eliminating nest parasites by doing nest replacements can mean the difference between life and
death for martin nestlings. Most people are afraid of replacing a martin nest for fear of causing the
parents to abandon the nest. But touching baby birds will definitely not cause the parents to
abandon them. This 'old wives tale' is untrue. By the time martins have built nests, laid eggs, and
hatched young, they've invested an enormous amount of time and energy in their reproductive
effort and will not be discouraged when they witness humans handling their young. Thousands of
nest changes are conducted every year by conscientious Purple Martin landlords.
Replacing a nest simply means removing a parasite-infested nest from a martin compartment or
gourd while the young are still living in it and replacing it with a bed of clean, dry material. By the
time nestlings are about 10 days old, the typical martin nest is crawling with a variety of parasites
that weaken and sometimes kill the martin nestlings. The three main nest-dwelling parasites are
fleas, mites, and blowflies. They are harmless to humans, but can be deadly to the young growing
Blowflies (Protocalliphora hirundo) are common in the northern part of the martins' range. The adult
blowfly resembles a common housefly and lays her eggs in the nest material when the martin
nestlings hatch. The larvae (or maggots) hide in the bottom of the nest during the day (see Fig. 1 at
the bottom of this page), then attach themselves to the nestlings at night and take blood meals (i.e.,
suck their blood). Hundreds of these maggots can sometimes be found in a single martin nest. If we
were to view blowfly parasitism from a human perspective (which it is improper to do), it would be
like trying to sleep in your bed at night with dozens of banana-sized, bloodsucking maggots
intermittently feeding on you.
Mites (Dermanyssus prognephilus) are a 1-mm-long bloodsucking arachnid that sometimes occurs
in large numbers and can be observed crawling all over the nests, cavity walls, entrance holes, and
porches of martin houses and gourds. Nest mites eat the skin and drink the blood of their hosts.
Heavy infestations can cause death or premature fledging of nestlings because parent martins
simply refuse to enter the nest cavity to feed their young.
Fleas come in 2 species (Ceratophyllus idius in the eastern U.S. and Ceratophyllus niger in the
western U.S.). It's not unusual to find hundreds of fleas and a few thousand of their larvae in a
martin nest. Only adult fleas take blood meals.
In Texas, our main parasite is the mite, but other nesting cavities further north have been observed
with all 3 of the above mentioned parasites. Many martin nests contain so many parasites, in fact,
that the entire nest bowl is a seething and writhing mass of parasites and pulverized nest material.
When food is plentiful and parents are attentive, parasites usually won't cause the death of a
substantial number of martin nestlings. After all, martins have co-evolved over millions of years with
these parasites. However, if food becomes scarce because of foul weather, or inexperienced (SY)
parents do not bring in enough food, the energy drain inflicted by these parasites can weaken or kill
even healthy nestlings. Under normal conditions, replacing the nest material when the young are
about 10 days old, and then again when they're 20 days old, eliminates the majority of nest
parasites, allowing runts and other marginally-healthy nestlings to survive.
To do nest replacements, you'll need a bag of replacement nesting material (preferably soft, dry pine
needles), a deep, 5-gallon bucket to temporarily hold the nestlings, a putty knife or similar
instrument to scrape out nest debris, and a container for the old material you remove. A bottle of
rubbing alcohol and a rag should also be on hand for wiping down the interiors of mite-infested
cavities, as well as cleaning your hands between replacements. Although martin parasites are not
harmful to humans, nest mites and feather lice can crawl onto you and be annoying, plus there is a
considerable amount of dust and debris that is kicked up when doing nest replacements. Therefore,
if you have a large number of nests to replace, you might consider wearing long sleeves and pants,
a dust mask, and goggles.
Basic Nest Replacement Steps
1. Remove and inspect the young. Pull off and discard any blowfly larvae that are attached. Place
the nestlings into a bucket already lined with a few inches of fresh nesting material (see Fig. 2).
2. Take a good look at the nest. Observe where the nest bowl is located and how deep it is. Next,
remove all of the nest material from the compartment or gourd and scrape out the bottom of the
compartment to insure removal of all blowfly larvae. In the case of gourds, dump the remaining
debris/blowfly larvae out the access door or push them out through the drainage holes (check to
make sure these are not clogged).
3. If the housing is heavily infested with nest mites, quickly wipe down interior and exterior surfaces
with a rag and rubbing alcohol. You don't need to search out every last mite, blowfly larva, and flea;
as long as you remove most of the nest material, you will have removed most of the parasites.
4. Insert a handful or two of fresh, dry nesting material (soft pine needles) into the cavity . Pat this
material down to form a 1&1/2- to 2-inch-thick "bed." Finally, form a depression or bowl in this
bedding and deposit the nestlings into it.
Repeat the procedure for each nest to be replaced. You may find that some active nest cavities
contain very little if any nesting material. Insert the same amount of replacement nesting material as
you would for all other nests. Never attempt to replace more than one nest at a time or you risk
mixing up nestlings. While you don't need to rush, move as quietly and as quickly as possible,
especially when there are a large number of nests to replace, in which case you might consider
staggering your replacements (i.e., do some one day, some the next). Aim for taking no longer than
two or three minutes per nest. If your changes take longer, you are being too fussy. Never perform
nest checks or nest replacements very early or late in the day, or on days when the weather is poor
and the young are stressed by lack of food. Dispose of removed nests promptly; it is against the
law to possess nests, eggs, or migratory birds.
Don't be alarmed if, after raising the purple martin housing, the parents are at first reluctant to
reenter their cavities. A few may recognize a change in their nest and be mildly alarmed, but they will
accept the change within a few minutes and resume feeding their young. Nest changes will not
IMPORTANT: Although blowflies and other parasites usually don't become a problem until nestlings
are about 10 days old, they occasionally cause the death of nestlings that are younger (see Fig. 3).
Few things are sadder for a landlord than finding dead nestlings in a parasite-infested nest during
their first seven-day nest check, especially if they worked and waited for years to attract martins.
Therefore, new landlords who have only one or two pairs of breeding martins, and who want to be
extra-vigilant in insuring the survival of their colony, should do nest checks more frequently, such
as every three days instead of every five to seven days. Remember, blowfly larvae often hide in the
bottom of the nest during the day and won't always be obvious to the landlord when he or she just
looks into a nesting cavity. However, gently digging into the nesting material just beneath the
nestlings will expose blowfly larvae if they are numerous.
Although nest replacements are not recommended for nests with young that are less than 10 days
old, in cases of early infestation, doing one can mean the difference between life and death.
However, special care must be taken in replacing the nests of very young nestlings (i.e., nestlings
1-8 days old). It is especially important to form a good artificial nest bowl or depression in the bed of
replacement nest material and line it with small green leaves (see Fig. 4). This leaf-lined bowl insures
that the nestlings will stay in a tight huddle so the female can cover and brood them properly. The
majority of the nest parasites are usually concentrated in this nest bowl area.
We realize that many landlords are reluctant to do nest checks, let alone nest replacements. But
once a purple martin landlord sees a typical, parasite-infested martin nest, they are usually very
shocked and instantly become "nest-change converts." Please consider doing nest replacements,
especially if you live in an area where martins are scarce and every healthy fledgling you produce in
your colony might help to rebuild the population in your region. Remember, many new colony sites
are established by just one pair of martins. Some landlords try for years, even decades, to attract
that first breeding pair. The nestling that you helped survive could become some landlord's future
matriarch or patriarch!
|Purple Martin Nest Replacement
|Fig. 1 Blow Fly Larvae
|Fig. 1 Blow Fly Larvae
|(reprinted by permission of the Purple Martin Conservation Association)
|Problem: Controlling West Nile Virus
Solution: Purple Martin & Bat Houses