FRAZAR’S
AMERICAN
OYSTERCATCHER
Banded-bird reports provide valuable information about the American oystercatcher. Place: J.A. Castillo Guerrero
Photo: Miriam Lerma
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By: Miriam Lerma and José Alfredo Castillo Guerrero
T
he American oystercatcher (Haematopus
palliatus) is a medium-sized shorebird with
a bright red-orange peak and pink legs. It
is found in both of the American coasts
and there are at least five subspecies.
The Frazar’s American oystercatcher (Haematopus palliatus frazari) inhabits Northwestern Mexico.
It is different from other subspecies for being larger
and darker, and for having very little or no white in
the feathers on its wings and a mottled breast.
There are approximately 3000 individuals in the
coasts and islands of Northwestern Mexico, between Nayarit and Baja California; although, most
of them are in the states of Sinaloa and Baja California Sur. Distribution and reduced population size,
and the increased threat to their habitat has caused
the Mexican government to classify the Frazar’s
American oystercatcher as an endangered species.
Frazar’s American oystercatcher breeding season
is between April and July. It begins with the selection of a place for their nest, which is later defended
from other couples of oystercatchers. The oystercatcher’s first mating takes place when they are 3
or 4 years old and they will use the same spots to
nest each year. Their bond as couples can be maintained for several years, even a lifetime.
The nest consists in a small scrape in the ground
with rocks, shells or vegetation; 1 to 4 eggs are laid
(2 on average) and incubated for 27 days. Once
they hatch, fledglings leave the nest after just a few
hours. They follow their parents and are fed by both
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AUGUST 2016
of them for 35 days, until they begin to fly and start
to feed themselves.
After the breeding season, oystercatchers leave
their breeding sites, stop being aggressive with other
oystercatchers and gather in communal places to
feed and rest.
Since their main source of food consists in oysters
and clams, tide limits the access to their feeding places.
Therefore, when tide is low, they feed in mires; while
when tide is high, they rest in safer places.
Current research is aimed at helping to protect
this subspecies. In the areas where larger numbers
of oystercatchers live, a monitoring program was
launched to evaluate their population state, survival, and reproductive success.
Among the activities that are taking place, there is
bird ringing. In Northwestern Mexico, metal bands
are attached to oystercatchers, one in the right
lower leg and a green band in the upper left leg.
The report of banded individuals provides valuable
information about movement, survival and demography of the species.
Human activities have caused changes in the
coastal zone of Northwestern Mexico. Habitat degradation is a result of the construction of different types of infrastructure, such as marinas, decks,
breakwaters, houses, shrimp farms, among others.
Increase in use of the coastal areas, like the rise
of disturbance levels, pollution and habitat degradation, is implicitly threatening the conservation of
the American oystercatcher.