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by TED L. CLARK
Wildlife Biologist
BANDING studies have showed that Texas white-
winged dove populations are not replenished by
Mexican birds, as many hunters have long thought
("Birds Across the Border," Texas Game and Fish, April
1964). In fact, biologists believe that many Texas white-
wings displaced by loss of habitat have adopted Mexican
nesting sites. To gain such information requires many
hours of banding in Mexico as well as Texas.
To make their factual picture as complete as possible,
Parks and Wildlife biologists have augmented their
Texas whitening banding program with annual forays
into Mexico. Since 1950, they have, with the permis-
sion of the Mexican government, each spring banded
a number of nestling birds on Mexican breeding
grounds. Through 1963, 22,034 whitewings have been
banded in Mexico: 21,697 nestlings and 337 adults.
Virtually all of these birds were banded in either the
San Fernando or Mante colonies, the largest in Mexico.
To initiate the banding program in Mexico, the
biologists first had to locate the major nesting colonies
south of the border. During 1950-54, an extensive recon-
naissance was made of that portion of Mexico east and
north of a line from Nuevo Laredo south to Ciudad
Valles, hence east to Tampico.
As early as 1952, preliminary call count transects
were established in the more important Mexican col-
onies. In other words, the biologists studied the num-
ber and frequency of whitewing calls in these colonies
to gain some idea of nesting populations. These early
investigations indicated widespread distribution of the
species over the more arid regions where live water
courses and waterholes occurred and where, at the same
time, dense low-growing brush existed. Mountainous
areas with lush vegetation as well as the rank coastal
type of vegetation (dense growths of bamboo and
willow) had practically no nesting birds. Major nest-
ing concentrations were found east of San Fernando
on the Rio Conchos, along the Rio Soto la Marina and
its tributaries east of Padilla, in the vicinity of the vil-
lage of San Jose de los Russios, and along the Rio
Guayalejo approximately 15 miles east of Ciudad
Mante (Figure 1).
By 1955 the call count technique of determining
population trends, described earlier, had been refined
and was established as the best method of getting
population indexes for the colonies. It is the basis of
techniques now used for both Texas and Mexican band-
ing projects.
From their data, biologists found that a comparison
of whitewing population fluctuations in Texas and
Mexico reveals similar trends for the period 1955-61
(Figure 2). This indicates that both the Texas and
Mexican populations are being subjected to the same
decimating factors on their common wintering grounds
in southern Mexico and Central America.
But, during the two nesting seasons since the devas-
Figure 1
wR iTEwW 'Itc SAN FENAD
NESTING AREAS
IN NORITHEASTERN-
fi[X1(6E
BATTERED NESTING
DENSE NESTING COONY
- - '-'- cNEDAD TADERO
SAD Yicro TAM. J co
Map shows major nesting areas-east of San Fernando, on Rio Conchos;
along Rio Soto a Marina, and tributaries east of Padilla near San Jose
de los Russios; along Rio Guayalejo, 15 miles east of Ciudad Mante.
TEXAS GAME AND FISH
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