STUDIES on the FAUNA of CURAÇAO and OTHER CARIBBEAN ISLANDS: No
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STUDIES ON THE FAUNA OF CURAÇAO AND OTHER CARIBBEAN ISLANDS: No. 60. Life History of the Red-legged Thrush (Mimocichla plumbea ardosiacea) in Puerto Rico by Francis J. Rolle (University of Puerto Rico, Biology Department, Mayagiiez) page Introduction 1 Systeraatics 4 Sex determination 7 General activities 10 Voice 12 Food and foraging 15 Courtship and territory 18 Nests and nest building 21 and incubation 24 Eggs, egg laying, of and of 28 Hatching eggs development young Parental of the 31 care young 33 Comments on the breeding season Roosting and late-hour activities 34 Summary and conclusions 36 Bibliography 38 To the ornithologist the West Indies offer an assortment of field In that problems. an area where it is unlikely new species of birds will be and where of discovered, the life histories only a handful of birds are known, concentrated study of individual life histories becomes of prime importance. the third formal life of This paper represents history study a resident Puerto bird and second of Rican the a passeriform. 2 BIAGGI’S work the Rican of (1955) on Puerto race the Bananaquit the (Coereba flaveola portoricensis) was first life history done on the island with any degree of thoroughness. More recently RODRÍGUEZ- VIDAL (1959) made a three-year study of the Puerto Rican Parrot (Amazona vittata vittata), which has brought to light interesting informationon its previously unknown breeding habits. SPAULDING (1937) wrote three short papers in which she set down her observa- tions on the nesting habits of three native birds. The works in mentioned above plus a few scattered notes found the literature on nesting, distribution, and eggs make up the largest part of the published information concerning the Puerto Rican avifauna. of is when consider The paucity information evident we that Puerto Rico has a total of 108 resident birds. Little has been published on the life history of the West Indian Red-legged Thrush ( Mimocichla plumbea). References to the thrush in Puerto Rico consist primarily of its inclusion in lists of birds seen on the island by various visiting ornithologists with perhaps a and distribution. half-dozen remarks or so on the nest, eggs, The resident Red-legged Thrush, or "zorzal de patas coloradas" as it is called in Spanish, is the only representative of the avian Turdidae the island. The alike and the family on sexes are average about 125 length of adults is mm. WETMORE (1922), in his investigations of bird remains from caves in Puerto Rico, found the bones of this thrush to be abundant. in From Cueva Catedral, Morovis, 40 right and 26 left humeri were secured. Remains were also found in three other caves. These have an estimated age of 100 to 2000 years, and their presence in the the owls. caves has been attributed to deposition of pellets by Either the Puerto Rican Barn Owl (Tyto cavatica), known only from fossil remains, or the Bare-legged Owl ( Otus nudipes nudipes) could be responsible for these pellet remains. The Puerto Rican Barn Owl was known to roost in caves. The Puerto Rican Bare-legged Owl generally roosts in trees but WETMORE (1922: 320) states that found bones of in the BENT he this species several caves on island. (1938: 251) states that the Eastern Screech Owl (Otus asio naevius), which is comparable in size to the Puerto Rican Bare-legged Owl, known feed robins and So has been to on even larger birds. the 3 question is whether the Puerto Rican Bare-legged Owl was partly responsible for the Redleg thrush remains or whether this small owl times fed the Puerto Rican Barn Owl. It is was at upon by larger unlikely that the Puerto Rican Short-eared Owl ( Asio flammeus portoricensis), has had anything to do with these thrush remains since its normal habitat is marshes and The remains grassy lagoons. indicatethat at the times the deposits were made the Redlegs must have been common and well distributed on the island. The present study of the Red-legged Thrush extended from August 1960 until July 1961. The main observations on nesting of the of Puerto at were made on the campus University Rico Mayagiiez in the southwestern portion of the island. Other obser- and such vations investigations as those pertaining to feeding habits and roosting were carried out on this campus and also on part of an 80-acre tract of land known as "La Finca Colegial". Some work done of in was on the grounds the Federal Experiment Station On each and Mayagiiez. area some trapping color-banding was accomplished. During the course of the work specimens were collect- ed and prepared. A limited numberof eggs and nests were also taken. Measurements are those indicated as being especially useful by OBERHOLSER & WORLEY All in BALDWIN, (1931). weights are grams where in millimeters. and all measurements, except noted, are This paper was presented to the Graduate Faculty of the Louisiana State Uni- versity and Agricultural and Mechanical College as a thesis in partial fulfillment of the requirements for the degree of Master of Science in The Department of Zoology, Physiology, and Entomology, January 1962. I to VIRGILIO the am particularly grateful Professor BIAGGI, JR., of University of Puerto Rico, for offering suggestions duringthe course of the field work and for reading portions of the manuscript in semifinal draft. Mr. ALLAN PHILLIPS, of the Agricultural Experiment Station, University of Puerto Rico, aided in the statistical analysis of specimens. My thanks are extended to the curators of the following museums for the loan of specimens: Academy of Natural Sciences of Philadelphia, American Museum of Natural History, British Museum (Natural History), Chicago Natural History Museum, Carnegie Museum, and United States National Museum. A Postgraduate Scholarship from the University of Puerto Rico in 1960-61 provided financial aid that enabled me to return to the island to carry out the field work. 4 Dr. ROBERT J. NEWMAN and Mr. STUART L. WARTER of the Museum of Zoology and Professors HARRY J. BENNETT, H. BRUCE BOUDREAUX, and J. HARVEY ROBERTS of the Department of Zoology, all at Louisiana State University, have taken time to read and criticize the manuscript. Professor GEORGE H. LOWERY, JR., directed the project and offered guidance throughout the entire study. SYSTEMATICS Thrushes of the Mimocichla the West Indies. genus are peculiar to All the confined the Greater geographic races except one are to related to members of the Antilles. These thrushes are closely genus Turdus; indeedsome workers do notrecognize the genus Mimocichla, Turdus. is in but merge it with RIPLEY (1952: 18, 19) favor of the since he feels that the of supressing genus presence a strongly- graduated, white-tipped tail, the principal morphologic character used to separate Mimocichla from Turdus, is not sufficient ground I with for maintaining the two as separate genera. agree BOND (1956: 128) and VAURIE (1957: 308) that Mimocichla should be for retained as a separate genus, the morphologic character stated above, because of the peculiar coloration of the orbital ring, bill, and legs, and on the basis of behavioral differences as well. At first the adults of the Thrush be much glance Red-legged appear to very like Robins urdus After obser- American (T migratorius). numerous Red- vations, however, one becomes aware that, even though the others legged Thrushes may resemble robins in many ways, in they do not. They are much more secretive and shy in their mannerisms, BOND VAURIE as noted by WETMORE (1916: 92) and by (1947: 166). ( 1957: 309) remarks that in western Cuba Red-legged Thrushes at behave much like the American Robin but adds that times very of their be to those of the Catbird some actions may compared (Dumetella carolinensis) and the Mockingbird (Mimus polyglottos). The Puerto Rican Redleg does not resemble either of these two mimids in any of the mannerisms I noted. The four species, plumbea, ardosiacea, rubripes, andravida, of the Mimocichla RIDGWAY have genus as once recognized by (1907: 79) now been reduced to two (BOND, 1956: 128). Mimocichla rubripes and M. ardosiacea have been designated as geographic races of ravida is distinct Mimocichla plumbea. Mimocichla a species found 5 on Grand Cayman, and BOND (1956: 128) considers it to be a deri- vation from a form now extinct on Jamaica. Mimocichla plumbea has been divided into six geographic races Bahama by BOND (1956: 128). These are: M. p. plumbea, northern Fig. 1. The Red-legged Thrush of Puerto Rico (Mimocichla plumbea ardosiacea). Islands; M. p. schistacea, extreme eastern Cuba; M. p. rubripes, central and western Cuba, Isle of Pines, and the Swan Islands; M. p. coryi, Cayman Brae; M. p. ardosiacea, Hispaniola (including Gonave and Tortue Islands) and Puerto Rico; and M. p. albiventris, Dominica. This last race is the only representative of the genus in the Lesser Antilles. Of historical interest are the taxonomic changes that have been madewith respect to the Hispaniolan and Puerto Rican populations. BRYANT (1867: 92, 93) was the first to separate the two populations. 6 His comments are as follows: "On comparing the series from Port with that from Porto au Prince, Rico, appreciable, though slight, differences can be detected, the bill and tarsi are brick red, instead of dull reddish-brown; the white tips of the tail feathers terminate obliquely toward the base, instead of being generally transverse; Fig. 2. Drawing showing some of the generic characters of the Red-legged Thrush (Mimocichla plumbea). the bill is absolutely as well as relatively smaller; the wing is longer, the tail shorter... The Porto Rican bird may be called Turdus ardosiaceus in var., portoricensis.” WETMORE (1927 : 491), com- menting on the birds from Puerto Rico, said that when taken in series in bill they were larger and tail measurementsand had a more color than slate-gray the Hispaniolan birds, which have a bluish tinge.