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قراءة كتاب Vertebrates from the Barrier Island of Tamaulipas, México

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Vertebrates from the Barrier Island of Tamaulipas, México

Vertebrates from the Barrier Island of Tamaulipas, México

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دار النشر: Project Gutenberg
الصفحة رقم: 3

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(49-62)

77.0±0.7
(69-85) 0.731±0.001
(0.682-0.817) Female 14 50.9±0.5
(47-53) 62.2±0.9
(57-68) 0.825±0.001
(0.735-0.877)

[A] Mean ± standard error; range indicated in parentheses.

Cnemidophorus gularis Baird and Girard: Whip-tailed Lizard.—At both camps we found this species in the same general habitat in which Holbrookia occurred, but in numbers decidedly fewer than the latter.

Specimens (4): 2 ♀ ♀ adult, 63489, 63490, Camp 1, July 7. 1 ♂ adult, 63491, 1 ♀ adult, 63492, Camp 2, July 9.

We failed to take specimens of snakes on the barrier island, but tracks of snakes were noted on two occasions in dunes near Camp 1; one trail led into a burrow of a kangaroo rat.

Birds

Unless otherwise indicated, specimens taken were not molting. For birds undergoing postnuptial or postjuvenal molt, the degree of advancement of the molt is indicated by recording the number of primaries of the old plumage that have not been dropped. For example, the designation "4 P old" signifies that all primaries except the distal four have been molted.

Table 2 presents results of a strip census of birds along the strand, made by three of us from the moving truck on the morning of July 10. Birds characteristically found on sand near the surf were thus conveniently counted in accurate fashion. Birds not ordinarily found on the strand could not be treated this way; most were considerably less abundant than the eight most numerous species listed in Table 2. Over-all, the numbers of individuals listed are a good index of abundance of the Great Blue Heron and of the common charadriiform birds on the beach in early July. The Black Tern is an exception, however, and this is discussed in the account of that species on page 327.

Table 2.—Birds[A] Recorded Along 17 Miles of Beach[B] on the Barrier Island of Tamaulipas

Species Number Birds per mile
Great Blue Heron 9 0.5
Oyster-catcher 1 0.1
Black-bellied Plover 20 1.2
Wilson Plover 53 3.1
Willet 43 2.5
Sanderling 55 3.2
Laughing Gull 136 8.0
Black Tern 19 1.1
Caspian Tern 82 4.8
Least Tern 221 13.0
Royal Tern 301 17.7
Cabot Tern 122 7.2
  Total: 1062 Total: 62.4

[A] Common Tern, Forster Tern, and Long-billed Curlew also seen but not counted.

[B] Between 56 and 73 miles south of Washington Beach, 11:00 to 11:45 a. m., July 10, 1961.

Pelecanus erythrorhynchus Gmelin: American White Pelican.—A flock of approximately 300 individuals was seen resting at the edge of the Laguna Madre near Camp 2 on July 9. When disturbed by gunshots, the birds circled high over the laguna and flew to the west. Among bones found on sand flats at Camp 1 are a left tarsometatarsus and a pedal phalanx of an American White Pelican.

Supposedly the only breeding colony of this species on the northern Gulf coast is one in the Laguna Madre near Corpus Christi (Peterson, 1960:8), but the possibility of one or more such colonies existing in northeastern Tamaulipas has been suggested by Amadon and Eckelberry (1955:68) on the basis of their observations of individuals seen soaring near the coast 15 to 20 miles south of Brownsville on April 15 and June 5, 1952. According to Hildebrand (1958:153, and personal communication, August 14, 1961), small colonies of white pelicans do breed in some years on two small islands, in the Laguna Madre of Tamaulipas, located at 25° 26´ North and 93° 30´ West.

In Veracruz the species is recorded as a winter visitant and transient (Loetscher, 1952:22; Amadon and Eckelberry, 1955:68). Coffey (1960:289) reports the following observations for Veracruz and Tamaulipas: a flock of 52 between Tlacotalpan and Alvarado, May 29, 1951; 80 near Cacaliloa, April 20, 1958; 180 birds north of Alvarado, April 24, 1958; four at Altamira, May 28, 1955; flocks of three, 13, and 37 "south" of Matamoros, May 20, 1951; 72 at Lomas del Real, November 20, 1956.

Pelecanus occidentalis Gmelin: Brown Pelican.—Three individuals flew north over the surf near Camp 1 on July 7, and a lone bird was seen diving into the Gulf a short distance beyond the surf near Camp 2 on July 9. Birds seen by us probably were of the population named P. o. carolinensis, which is resident along the Gulf coast (Mexican Check-list, 1950:21).

Phalacrocorax sp.: Cormorant.—From 80 to 100 adult and juvenal cormorants were on the laguna at Camp 2 on July 8 and 9. Probably they were Common Cormorants (P. olivaceus), but, because specimens were not taken, we cannot eliminate the possibility that some (or all) were Double-crested Cormorants (P. auritus). The former breeds in coastal lowlands of eastern México, whereas the latter is known in eastern México only as a winter visitant and has not been recorded in Tamaulipas (Mexican Check-list, 1950:24).

Fregata magnificens Mathews: Magnificent Man-o'-war Bird.—An observation of a lone bird circling high over the laguna at Camp 2 on July 9 seemingly constitutes the third record of this species in Tamaulipas. Previous records were reported by Robins, Martin, and Heed (1951:336), who found "large numbers" in the Barra Trinidad region (8 miles

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