GULF OF MEXICO 



533 



Visitants to Coast Not of Regular Annual Occurrence — Continued 



***Sabine Gull, Xema sabini. — One taken at Corpus 

 Christi, Texas, October 4, 1889: one seen on Padre 

 Island, Texas, December 30, 1951. 



Despite the great geographic extent of the 

 Gulf of Mexico, only one species of bird is endemic 

 to its shores or to its islands, in the sense that it 

 occurs there and nowhere else. This is the Cape 

 Sable sparrow, a bird so closely related to Am- 

 mospiza maritima that some taxonomists would 

 prefer to place it under that species. However, 

 at least 16 subspecies peculiar to the Gulf area are 

 rather generally recognized. While the present 

 summary deals primarily with the status of birds 

 as species, these endemic races are a subject of 

 considerable pertinence, since they reveal the 

 effectiveness of the Gulf perimeter in the develop- 

 ment of geographic variations. Of these subspe- 

 cies restricted to the Gulf coast, four are seaside 

 sparrows: Ammospiza maritima peninsulae, occur- 

 ring from Tampa Bay to Lafayette County, Flor- 

 ida; A. TO. juncicola, from Taylor County to St. 

 Andrew Bay, Florida; A. m.fishen, from the coast 

 of Alabama to High Island, Texas; and A. m. 

 sennetti, from Galveston Bay at least to Corpus 

 Christi, Texas. Three are clapper rails: Rallus 

 longirostris insularum, of the Florida Keys; R. I. 

 saturatus, of the coasts from Alabama west at 

 least to Rockport, Texas; and /?. /. pallidw^, of 

 the northeastern coAst of the Yucatan Peninsula. 

 Two are long-billed marsh wrens: Telmatodytes 

 jMiuMris marianae, occurring fi'om Charlotte Har- 

 bor, Florida, to Mobile, Alabama; and T. p. thry- 

 ophilus, of the coasts of Mississippi, Louisiana, 

 and Texas. The remaining endemics with their 

 respective ranges are: the nominate race of the 

 great white heron, Ardea occidentalis occidentalis, 

 southern Florida and the Florida Keys; a reddish 

 egret, Dichromanassa rufescens colorata, the coast 

 of the Yucatan Peninsula and its offshore islands; 

 an insect hawk, Buteo magnirofitris gracilis, islands 

 off the northwestern coast of the Yucatan Penin- 

 sula; a barn swallow, Hirundo rustica insularis, 

 coastal islands and beaches from northwestern 

 Florida to southeastern Ix)uisiana; a horned lark, 

 Eremophila alpestris girawli, southwestern Louisi- 

 ana to northern Tamaulipas; a Carolina wren, 

 Thryothorus Ivdovicianus burleighi, islands off the 

 Mississippi coast; and a red-wing, Agelaius phoeni- 



***Elegant Tern, Thatasseus elegans. — One taken at 

 Corpus Christi, Texas, July 25, 1889. 



ceus littoralis, Choctawatchee Bay, Florida, to 

 Galveston, Texas. 



A striking feature of the coastal bird list is, 

 however, that it includes only three species that 

 have never been recorded in the United States. 

 Many a person interested in birds tends to think 

 of tropic shores as places teeming with strange 

 and unfamUiar species; but to the extent that this 

 expectation is realized around the southern half 

 of the Gulf, it is mainly fulfilled by those resident 

 land birds whose home ranges happen to adjoin 

 tidewater or to encroach upon it. The birds of 

 the lower orders, the water bu-ds that necessarily 

 make up the great bulk of any coastal avifauna 

 in the strict sense, are for the most part species 

 of ancient origin that have extended their ranges 

 over vast areas of the hemisphere and the world. 

 The tropical water birds that have occurred in the 

 lands bordering the Gulf but have never reached 

 the United States are, with the exception of the 

 three named in the summary and one accidental, 

 all primarily inland species, at least insofar as 

 available records reflect their distribution. The 

 group is a rather small one, consisting of eight 

 rails, four ducks, four herons, two sun-grebes, two 

 shorebirds, a stork, and a tern. Twenty-nine 

 species in the summary have yet to be reported 

 from the southern half of the Gulf, but well over 

 half of them are not of regular annual occurrence. 

 If we were to divide the Gulf into an eastern and 

 a western half by a line passing between Louisiana 

 and Mississippi and along the western edge of the 

 Yucatan Peninsula, that is, approximately by the 

 90th meridian, we would find that only four of 

 the listed breeders and regular visitants have never 

 been observed on the shores west of the line, while 

 only three have yet to be seen on the shores east 

 of it. To put these facts in a different way, all 

 but 19 of the birds in the groups of regular annual 

 occurrence have occurred at times and places on 

 the northern and southern, as well as the eastern 

 and western, Gulf coast. The real coastal avi- 

 faunas of all sections thus have a tremendous 

 common denominator, and their variance is more 

 a matter of relative abundance of individuals of 



