was moderately common along the beach and margin of the laguna, and it
was seen frequently in company with Royal Terns. Like the latter, this
tern breeds in coastal Texas (A.O.U. Check-list, 1957:241), and it
probably also nests in Tamaulipas, although direct evidence is not
available. The only previous record of this species in Tamaulipas is a
report (Robins, Martin, and Heed, 1951) of two observed on the beach
near Tepehuaje on May 9, 1949.
Specimens (4): [M], 38965, testis 9 x 4.5 mm., 208 gm., 9 P old, 49
miles south of Washington Beach, July 8. Male, 38966, testis 8 x 3 mm.,
not fat, 192 gm., 8 P old; [F], 38967, ova to 3 mm., 193 gm., 7 P old,
brood patches refeathering; [F], 38968, ova to 1 mm., 186 gm., 8 P old,
no brood patches; 52 miles south of Washington Beach, July 8.
=_Rynchops nigra nigra_= Linnaeus: Black Skimmer.--We found this
species moderately common at the edge of the laguna at both camps and
occasionally saw it along the beach. Generally two birds, probably
mated pairs, were seen together; twice birds were seen carrying food in
their bills, presumably intended for nestlings. The species is known to
nest in Tamaulipas from "Matamoros Lagoon" south to Tampico (Mexican
Check-list, 1950:112).
Specimens (2): [M], 38970, testis 40 x 23 mm. (abnormally large,
possibly as a result of hemorrhage), 418 gm., brood patches
refeathering; [M], 38969, testis 17 x 4 mm., fat light, 442 gm., brood
patches refeathering; Camp 1, July 7.
=_Zenaidura macroura_= Linnaeus: Mourning Dove.--Our only record is a
lone bird seen in a mesquite near Camp 1 on July 6. Possibly the
species breeds along the margin of the laguna, although Aldrich and
Duvall (1958:113, map) do not include coastal Tamaulipas in the known
breeding range. Loetscher (1955:30) suggests that the Mourning Dove may
be found breeding in the lowlands of northern Veracruz and cites a
record of one seen at Tamos on July 1, 1952.
=_Geococcyx californianus_= (Lesson): Road-runner.--At least four
individuals were seen in large dunes at Camp 1 on July 7 and 8. On
several occasions we watched them pursue lizards (_Holbrookia
propinqua_) at the margins of clumps of _Croton_ and _Ipomoea_.
=_Chordeiles minor aserriensis_= Cherrie: Nighthawk.--Nighthawks of
this species were seen regularly at Camp 1, where we flushed them from
alkaline flats in the day and heard them calling as they foraged over
the dunes in late afternoon.
Specimens (3): [M], 38971, testis 5 mm., no fat, 62 gm., Camp 1, July
6. Male, 38972, testis 7.5 mm., no fat, 58 gm.; [M], 38973, testis ?,
no fat, 53 gm.; Camp 1, July 7. The gonads of these birds were not in
full breeding condition, but it is highly probable that the birds were
members of a population that had bred in the area.
Variation in _Chordeiles minor_ in Tamaulipas has recently been studied
by Graber (1955). Two specimens taken by him on August 3, 1953,
approximately 9 miles south of Carbonera, resemble birds from Terrell
County, Texas, and represent _C. m. aserriensis_, as do our three birds
from the barrier island. Two of Graber's specimens from Lomas del Real,
in southeastern Tamaulipas, are distinctly darker and probably
represent _C. m. neotropicalis_, a subspecies subsequently described
from Chiapas (Selander and Alvarez del Toro, 1955).
=_Muscivora forficata_= (Gmelin): Scissor-tailed Flycatcher.--On July 7
near Camp 1, two individuals were found in stands of mesquite. One was
taken and proved to be an adult male (38974, testis 6 x 3 mm., not fat,
40 gm.) in postnuptial molt (6 P old).
We presume that the two birds recorded by us were members of a
population breeding on the barrier island, rather than autumnal
migrants. The Mexican Check-list (1957:69) records this species in
Mexico only as a transient and winter visitant. But, on the basis of
records of birds seen along the highway between Matamoros and Ciudad
Victoria, Davis (1950) has suggested that the species breeds in
Tamaulipas, and this is supported by a report of one seen at the north
end of the Monterrey Airport on June 1, 1957 (Coffey, 1960:294). Brown
(1958) has recently established that the species breeds in Nuevo Leon
by finding a nest 33 kilometers (by road) north of Sabinas, Hidalgo, on
July 19, 1954.
=_Myiarchus cinerascens cinerascens_= (Lawrence): Ash-throated
Flycatcher.--A juvenal male (38975, testis 2 mm., no fat, 35.0 gm.)
taken in mesquite at Camp 1 constitutes our only record for this
species. Lanyon (1961:441, map) has shown that most of Tamaulipas is
devoid of these flycatchers in the breeding season; the nearest known
breeding Ash-throated Flycatchers are slightly west of Corpus Christi,
Texas, about 200 miles north-northwest of Camp 1 on the barrier beach.
Our specimen closely resembles eight specimens from Coahuila, Mexico,
in general coloration and, especially, in the pattern of colors on the
outer rectrices. Probably No. 38975 was from southwestern Texas or
Coahuila and had begun its southward migration. Against this idea lies
chiefly the fact that young-of-the-year tend to move south later than
adults of the same species; so, this bird possibly had been reared in
coastal Tamaulipas.
=_Eremophila alpestris giraudi_= (Henshaw): Horned Lark.--This species
occurred in moderate numbers on alkaline flats and almost barren sand
flats at both camps. At the time of our visit to the island, the
breeding season apparently was coming to an end, but we noted no
tendency in the birds to flock.
Specimens (7): [M], 38981, testis 6 mm., 21.0 gm.; [M], 38977, testis
7.5 x 4 mm., not fat, 27.5 gm.; [M], 38979, testis 11 x 7 mm., 29.0
gm.; [F], 38976, ova to 3 mm., brood patch vascular but regressing, no
fat, 24.4 gm.; sex? juv., 38987, no fat, 21.0 gm.; sex? juv., 38980,
24.0 gm.; Camp 1, July 7. Male, 38982, testis 9.5 x 6 mm., 27.5 gm.,
Camp 2, July 9.
The subspecies _E. a. giraudi_, which is endemic to the Gulf coastal
plain of Texas and Tamaulipas, has been reported in Tamaulipas
previously only from Bagdad, near Matamoros (Mexican Check-list,
1957:106). The fact that our specimens show characters totally
consistent with those of _E. a. giraudi_ indicates that there is little
genetic interchange between the population we sampled and those of _E.
a. diaphora_, the closest of which reportedly breeds at Miquihana, in
southwestern Tamaulipas.
=_Corvus cryptoleucus_= Couch: White-necked Raven.--Several groups of
six to ten birds were present at Washington Beach on July 6 and 10;
but, southward on the island, we recorded this species only once, on
July 9, when a lone individual flew near Camp 2, being pursued and
"buzzed" by two Least Terns. The Mexican Crow (_Corvus imparatus_)
reportedly is common in the coastal region of Tamaulipas (Mexican
Check-list, 1957:118) but was not seen by us.
=_Thryomanes bewickii cryptus_= Oberholser: Bewick Wren.--This species
seemingly breeds in small numbers in mesquite stands near Camp 1, where
we obtained a juvenile and saw another individual. Specimen: [F] juv.,
38983, no fat, 10.0 gm., Camp 1, July 8. _T. b. cryptus_ is reported to
intergrade with _T. b. murinus_ of Veracruz in southern Tamaulipas
(Mexican Check-list, 1957:160-161).
=_Mimus polyglottos leucopterus_= (Vigors): Northern Mockingbird.--We
recorded this species only near Camp 1, where a few pairs were breeding
in stands of mesquite. Males were in full song and territorial display.
Specimens (2): [M], 38985, testis 11 x 7 mm., not fat, 43 gm.; [F],
38984, ova to 4.5 mm., vascular brood patch, 49.0 gm.; Camp 1, July 7.
PLATE 7
[Illustration: FIG. 1.--Mesquite-cactus formation on clay dune at
margin of the Laguna Madre west of Camp 1. Habitat of Northern
Mockingbird, Cardinal, Bob-white, black-tailed jackrabbit, and Great
Plains woodrat.]
[Illustration: FIG. 2.--_Batis-Monanthochloe_ formation on alkaline
flats near the Laguna Madre, with mesquite bordering stabilized dunes
in the left background. _Salicornia_, a classical dominant of salt
marshes, is here relatively inconspicuous. Habitat of Nighthawk and
Horned Lark.]
PLATE 8
[Illustration: "Fossilized" burrow of Texas Pocket Gopher in a sandy
trough between active dunes. A part of the cast has been broken away to
show the general shape of the old burrow. The diameter of the cast is
about 3.5 inches.]
=_Cassidix mexicanus prosopidicola_= Lowery: Great-tailed
Grackle.--Small, postbreeding flocks composed of both adult and juvenal
birds were seen moving along the edge of the laguna at Camp 1. In the
morning the flocks flew south, and in the afternoon groups of similar
size flew north, presumably to a roost at an undetermined distance
north of our camp. Occasionally, a few birds stopped to rest or to
forage on the dunes or in stands of mesquite. At Camp 2 on July 9, a
postbreeding adult female and a well-grown, presumably independent
juvenile were taken as they perched in a clump of mesquite in which we
found three old nests of _Cassidix_; two of the nests were about four
feet apart in one tree, and the third was in another tree 100 feet from
the first.
Specimens (4): [M] adult, 38988, testis 6 mm., no fat, 209 gm., 6 P
old, Camp 1, July 7. Female, 38989, ova to 3 mm., fat, 115 gm., old
brood patch, Camp 1, July 8. Female, 38990, ova to 1 mm., moderate fat,
107 gm., 7 P old, brood patch refeathering; [M] juv., 38991, testis 3 x
1 mm., not fat, 172 gm., 6 P old; Camp 2, July 9.
TABLE 4.--MEASUREMENTS IN MILLIMETERS OF ADULT MALES OF CASSIDIX
MEXICANUS
=============+=========+=========+=========+===========+============
| | | | | Weight in
LOCALITY | No. | Wing | Tail | Tarsus | grams
-------------+---------+---------+---------+-----------+------------
Austin, Texas|17-137[1]| 184.3 | 203.8 | 46.38 | 225.6 June
| |(173-200)|(178-232)|(41.8-50.0)| (204-253)
| | | | | 202.2 July
| | | | | (195-207)
| | | | |
San Patricio | 5 | 185.2 | 204.2 | 46.74 | 237.6
Co., Texas[2]| |(182-188)|(190-219)|(45.1-50.2)| (228-245)
| | | | |
Barrier Is., | | | | |
Tamps. | 1 | 178 | 185 | 47.1 | 209
| | | | |
Victoria, | 4 | 192.2 | 224.2 | 47.77 | 254.3
Tamps.[3] | |(186-200)|(215-232)|(46.0-49.1)| (239-276)
| | | | |
Tampico, | | | | |
Tamps.[4] | 1 | 197 | 214 | 48.3 | 260
| | | | |
Catemaco, | | | | |
Veracruz[5] | 1 | 193 | 216 | 48.2 | 257
-------------+---------+---------+---------+-----------+------------
[Footnote 1: Data from Selander (1958: 370, 373). Sample sizes, as
follows: wing, 137; tail, 119; bill length, 20 (June and July); tarsus,
133; weight, 17 for June, 3 for July.]
[Footnote 2: June 13, 1961; breeding condition.]
[Footnote 3: May 6, 1961; breeding condition.]
[Footnote 4: May 7, 1961; breeding condition.]
[Footnote 5: November 28, 1959.]
Specimens from the barrier island are clearly referable to _C. m.
prosopidicola_, showing no approach to the larger and, in the female,
darker _C. m. mexicanus_ of Veracruz and San Luis Potosi. In Table 4,
measurements of the adult male from the barrier island may be compared
with those of specimens of _C. m. prosopidicola_ from Texas and a
specimen of _C. m. mexicanus_ from Veracruz; it is apparent that our
specimen is assignable to the former.
Evidence of intergradation between the two subspecies is shown in a
series of birds collected near Ciudad Victoria, Tamaulipas, in May,
1961. The females in the series are highly variable in color
individually, but are on the average paler than _C. m. mexicanus_ from
Veracruz; the males are distinctly larger than _C. m. prosopidicola_
from Texas. At Miramar, near Tampico, Tamaulipas, a decided approach to
_C. m. mexicanus_ is also evident in the dark color of females and in
the large size of both males (Table 4) and females.
=_Agelaius phoeniceus megapotamus_= Oberholser: Red-winged
Blackbird.--This species was recorded only at Camp 1 on July 7, when we
saw two males, one of which was flying south along the edge of the
dunes in a flock of five Great-tailed Grackles. Specimen: [M], 38992,
testis 10 x 7 mm., fat, 54 gm., Camp 1, July 7. The large size of the
testes of this individual indicates breeding condition.
=_Sturnella magna hoopesi_= Stone: Eastern Meadowlark.--Meadowlarks
were found in small numbers along the margins of the alkaline flats at
both camps. Breeding was still in progress, for males were singing and
a female shot on July 9 had only recently laid eggs. Specimens (2):
[M], 38986, testis 13 x 8 mm., not fat, 102 gm.; [F], 38987, ova to 6
mm., 3 collapsed follicles, not fat, 88 gm.; Camp 2, July 9.
=_Richmondena cardinalis canicaudus_= Chapman: Cardinal.--This species
was recorded only in stands of mesquite near Camp 1, as follows: July
7, two pairs seen, from which a breeding female was taken; July 8,
three birds seen. Specimen: [F], 38933, edematous brood patch, 36.5
gm., Camp 1, July 7. Intergrades between the present subspecies and _R.
c. coccinea_ of Veracruz are reported from Altamira, Tamaulipas
(Mexican Check-list, 1957:329).
_Mammals_
=_Dasypus novemcinctus mexicanus_= Peters: Nine-banded
Armadillo.--Remains of an armadillo (89017) were found in a mesquite
thicket in the dunes near Camp 1 on July 7. The bones are not badly
weathered and were not embedded in sand.
This species has not been recorded previously on the barrier island of
Tamaulipas, nor, for that matter, on any of the barrier islands on the
western shore of the Gulf of Mexico.
=_Lepus californicus merriami_= Mearns: Black-tailed Jackrabbit.--From
two to four individuals were recorded daily in dunes and on alkaline
flats in the vicinity of stands of mesquite and cactus.
Specimens (2): [F] adult, 89018, pregnant (two embryos, 28 mm. in
crown-rump length), Camp 1, July 6. Male immature, 89019, Camp 1, July
7. Our specimens have been compared with two skins of _L. c. curti_
from the type locality at Eighth Pass, with which they agree reasonably
well in color. The size of the adult female is about that
characteristic of other specimens of adult _L. c. curti_, but
characters of the skull are consistent with those of _L. c. merriami_.
A specimen of this species from Matamoros and several from Brownsville,
Texas, have been assigned by Hall (1951:43) to _L. c. merriami_.
Specimens from Padre Island, Texas, reportedly resemble _L. c. curti_
in smallness of the tympanic bullae but are in other characters
referable to _L. c. merriami_ (Hall, 1951:44).
=_Spermophilus spilosoma annectens_= (Merriam): Spotted Ground
Squirrel.--These squirrels were moderately common in dunes at both
camps. They were heard calling, and many tracks and holes were seen. On
July 7, at Camp 1, a lactating, adult female (89020) and two dependent
juveniles (89021, skull only, 89022, skin and skull) were shot at the
entrance of a burrow; the uterus of the adult showed six placental
scars.
Our adult specimen has been compared with ten specimens obtained by
Hall and von Wedel at Eighth Pass in March, 1950; ours differs from the
ten in being paler and slightly larger. The pallor is perhaps
attributable to seasonal variation, and the size (246-79-38-7; weight,
133 gm.) is within limits that would be expected in a larger series of
the population sampled by Hall and von Wedel. Hall (1951:38) referred
specimens of this squirrel from Eighth Pass to _S. s. annectens_.
=_Geomys personatus personatus_= True: Texas Pocket Gopher.--This
pocket gopher was abundant on low, stabilized dunes on the barrier
island from four to 73 miles south of Washington Beach. One of us
(Wilks) made a trip down the beach on May 20 and 21, 1961, and
collected specimens at localities four miles south and 33 miles south
of Washington Beach; additional specimens were taken at both Camp 1 and
Camp 2 from July 6 to 10. At these localities the gophers seemed to
maintain population densities approximating those of _G. personatus_
on Padre and Mustang islands on the Texan coast.
There is but one other record of the Texas Pocket Gopher from Mexico.
Goldman (1915) described _G. p. tropicalis_ from Altamira on the basis
of specimens collected in 1898. Since that time, the species has not
been reported as occurring south of Cameron County, Texas (Kennerly,
1954), some 50 miles northwest of the closest station of occurrence of
the gophers on the barrier beach of Tamaulipas.
Our specimens are slightly smaller than _G. p. personatus_ and slightly
larger than _G. p. megapotamus_, the subspecies of nearest geographic
occurrence to the barrier island. The degree to which our specimens
differ in other respects, such as configuration of the pterygoid, is
being studied further by Wilks. For the present, reference of our
material to the nominate subspecies best expresses the relationships of
these coastal gophers.
The fact that pocket gophers from the Tamaulipan barrier island occupy
a position geographically intermediate between present Texan
populations and the isolated population in southern Tamaulipas (_G. p.
tropicalis_) helps explain the origin of the latter. It is likely that
_G. p. tropicalis_ represents the southern remnant of a once
continuously-distributed population of pocket gophers living in coastal
Tamaulipas in mid-Wisconsin to late Wisconsin time. At that time, sea
level is thought to have been considerably lower than at present,
exposing a sandy strip 80 to 100 miles wide off the present coastline.
Presumably this would have been an area suitable for gophers and for
southward dispersal of individuals from Texas. The only conceivable
barrier to dispersal, and thus to a panmictic population, would have
been the Rio Grande, but over the wide, low and sandy coastal plain the
river channel almost certainly shifted regularly, thus decreasing its
effectiveness as a barrier to movement. With subsequent rise in sea
level, the gophers at Altamira became isolated and have presumably
remained so for a considerable time. To judge by the marked morphologic
differentiation of _G. p. tropicalis_, its degree of isolation from
other populations has been much greater than those of populations
inhabiting the Tamaulipan barrier island and the barrier islands of the
coast of Texas. Contact between the latter two populations was probably
fairly regular before man's stabilization of the channel of the
lowermost reaches of the Rio Grande.
At Camp 1 we found evidence of the former occurrence of gophers in an
area now largely covered by active beach dunes. Numerous skeletal parts
of gophers and "fossilized" burrows (Plate 8) were found on the surface
where troughs between active dunes reached down to an older, darker,
and more tightly cemented layer of sand underlying the present dunes.
It is clear that these gophers were not transported there, because the
bones were not damaged, some of the skeletons were almost complete, and
many of the bones were found near the "fossilized" burrows. Weathered
but well preserved skeletal remains of at least 12 gophers were picked
up at this site.
Specimens (17): [F], 89023, Camp 1, May 20. 4 [F] [F], 89024-026,
89029; 3 [M] [M], 89027, 89028, 89030; Camp 1, May 21. Male, 89031,
Camp 1, July 6. Three [M] [M], 89032, 89035, 89038; 4 [F] [F], 89033,
89034, 89036, 89037; Camp 2, July 9. Female, 89039, Camp 2, July 10.
=_Perognathus merriami merriami_= Allen: Merriam Pocket Mouse.--An
individual taken in a trap in the dunes near Camp 2 constitutes the
first record of this species from the barrier island of Tamaulipas.
This pocket mouse seems to be uncommon on other barrier islands of the
western Gulf of Mexico, for there is only one published report of its
occurrence on Padre Island, Texas (Bailey, 1905:141). Other nearby
stations of occurrence are Altamira, Tamaulipas (Hall and Kelson,
1960:477), Brownsville, Texas (Bailey, _loc. cit._), and 17 miles
northwest of Edinburg, Texas (Blair, 1952:240).
Specimen: sex?, 89040, skull only, Camp 2, July 10.
=_Dipodomys ordii parvabullatus_= Hall: Ord Kangaroo Rat.--We found
this species uncommon and confined in distribution to dunes, in which
it was recorded as follows: an adult female was shot and two other
individuals were seen at night on July 6 at Camp 1; three were trapped
near Camp 1 on July 7; two were trapped at Camp 2 on July 10.
Specimens (5): [F], 89041, 2 placental scars, 46 gm., Camp 1, July 6.
Male, 89042, testes scrotal, 47 gm.; [M], 89044, 60 gm.; [F], 89043, 44
gm.; Camp 1, July 7. Sex?, 89045, skel. only, Camp 2, July 10.
Our material does not differ significantly from specimens obtained by
Hall and von Wedel at Boca Jesus Maria in March, 1950, which formed the
basis for Hall's description (1951:41) of _D. o. parvabullatus_. This
subspecies is presumably confined in distribution to the barrier island
of Tamaulipas. Two immature specimens from Bagdad, Tamaulipas, were
tentatively assigned by Hall (1951:41) to _D. o. compactus_, a
subspecies known otherwise only from Padre Island, Texas.
=_Neotoma micropus micropus_= Baird: Southern Plains Woodrat.--This
species was noted only near Camp 1, where numerous houses were seen in
stands of mesquite and prickly-pear cactus and an adult male (89046,
330 gm.) was taken on July 6. This species has not been reported
previously from the barrier island of Tamaulipas. Our specimen is
referable to the nominate subspecies and shows no approach to _N. m.
littoralis_, a subspecies known only from the type locality at
Altamira, Tamaulipas (see map, Hall and Kelson, 1960:684).
=_Procyon lotor_= (Linnaeus): Raccoon.--A weathered skull and a broken
humerus were found at Camp 2. The skull is being studied by Dr. E. L.
Lundelius, who informs us that it matches a number of raccoon skulls
found in archaeological sites along the Balcones Escarpment of Texas.
Such skulls are larger than skulls of raccoons occurring today in Texas
(_P. l. fuscipes_) and closely resemble skulls of raccoons (_P. l.
excelsus_) presently confined in distribution to Idaho, eastern Oregon,
and eastern Washington. Further details of this situation are to be
reported elsewhere by Lundelius.
=_Taxidea taxus_= (Schreber): Badger.--Two burrows were found in the
stabilized dunes near Camp 1, tracks were noted on the alkaline flats,
and a weathered skull (89047) was found on the flats west of Camp 1 on
July 7. The skull appears to be of an immature animal, for the sutures
are not well closed and the teeth show little wear.
Our records require an extension of known range of this species
southeasterly by approximately 50 miles. The only previous record in
coastal Tamaulipas is based on two skulls from Matamoros (Schantz,
1949:301). The skull from the barrier island cannot be determined to
subspecies but on geographic grounds is referable to _T. t.
littoralis_, with type locality at Corpus Christi, Texas.
=_Canis_= sp.--Numerous tracks made either by Coyotes (_C. latrans_
Say) or by domestic dogs were seen in dunes and on the beach at both
camps. A weathered, posterior part of a canid skull was found in dunes
at Camp 2 on July 10, and a partial left mandible was taken on the
beach at Camp 1 on July 6. Unfortunately, specific identification of
the skull fragments is not possible, but the few reasonably good
characters that we can use suggest that our material is of domestic
dogs rather than of Coyotes. Hall (1951:37) found tracks and other
signs of Coyotes at Eighth Pass but did not take specimens.
Most of the canid scats examined by us contained remains of crabs and
fishes.
=_Odocoileus virginianus_= (Boddaert): White-tailed Deer.--A weathered
Recent fragment of a mandible (89048) and part of a femur (89049) of
this species were found near Camp 1 on July 7, and a metapodal was
picked up in the dunes at Camp 2 on July 9. This species has not been
reported previously on the barrier island of Tamaulipas and it probably
no longer occurs there, for we saw no tracks or other signs of it. Hall
(1951) did not find it at Eighth Pass.
Our specimens probably pertain to _O. v. texanus_ but are possibly of
_O. v. veraecrucis_, which has been reported from Soto la Marina
(Goldman and Kellogg, 1940:89).
The only species of mammal known from the barrier island of Tamaulipas
that we did not find is the Hispid Cotton Rat (_Sigmodon hispidus_).
Two specimens of this species trapped near Eighth Pass in March, 1950,
formed the basis for the description of _S. h. solus_ (Hall, 1951:42),
a subspecies known only from the type locality.
Discussion