BIRD RECORDS FROM THE DRY TORTUGAS

Clive A. Petrovic and James King, Jr.

As guests of the National Park Service from 25 March to 4 April, 1967, we witnessed an early spring migration through the Dry Tortugas. These islands are located in the Gulf of Mexico about 70 miles west of Key West, Florida. Weather conditions during the period were unstable, being characterized by strong, variable winds. Rain was experienced only on 28 and 30 March.

Seventy species, the majority land birds, were recorded. Specimens obtained have been deposited in the collection of the University of Miami (UMRC), Coral Gables, Florida. Sincere thanks are extended to Oscar T. Owre and William B. Robertson, Jr., for reviewing the manuscript and for verification of the records.

• Gannet (Morus bassanus)--A skull (UMRC 5224) and several vertebrae picked up on Long Key on 28 March represent only the sixth record of occurrence at the Tortugas. A common winter resident in parts of coast­al Florida, this species undoubtedly occurs in winter near the islands.
• Red-breasted Merganser (Mergus serrator)--An individual (UMRC 5246) collected on Long Key on 28 March lends support to the suggestion (Robertson and Mason, 1965: 134) that this species may be a rare winter visitor. However, only six previous records exist.
• Marsh Hawk (Circus cyaneus)--Although recorded only 3 times, this bird may be a more common migrant than the records indicate (Sprunt, 1962: 40). Our sighting on 30 March is apparently only the fourth re­ported occurrence at the Tortugas.
• Herons--Robertson and Mason (1965: 132) stated that fairly heavy heron flights pass through the Tortugas in early spring. Our regular sightings of most heron species support this conclusion. Jn the last week of March we saw flocks consisting of Little Blue Herons (Florida caerulea), Cattle Egrets (Bubulcus ibis), Snowy Egrets (Leucophoyx thula), Louisiana Herons (Hydranassa tricolor), and Black-crowned Night Herons (Nycticorax nycticorax). A total of 11 heron species was observed during the 11-day period. Still, it seems odd that certain species were represented by few records until recent times. Sprunt (1962: 39) listed several now­common species as quite rare or uncommon at the Tortugas. This is probably best explained by a former lack of observers.
• Great White Heron (Ardea occidentalis)--This species is given to wandering and regularly reaches the Tortugas (Robertson, pers comm.). The first specimen from the Tortugas, a dried carcass, was collected on Bush Key, 28 March. The skeleton (UMRC 5200) was preserved.
• Least Bittern (Ixobrychus exillis)--A Least Bittern in adult plumage was flushed several times from the parade ground at Ft. Jefferson on 29 March. This bird flew with seeming difficulty. On 30 March, a freshly dead, much emaciated adult (probably the same bird) was found in a first-floor casemate of the fort. Its stomach was empty. The skin is UMRC 5221. There are 3 previous records of this species from the Dry Tortugas (Robertson and Mason, 1965: 133).
• American Bittern (Botaurus lentiginosus)--This species has been recorded at the Tortugas 3 times (Sprunt, 1962: 39). A lone bird, apparently the fourth record, was seen on the parade ground of Fort Jefferson on 26 March. The bird flew with apparent difficulty.
• Roseate Spoonbill (Ajaia ajaja)--A lone bird was photographed flying over Garden and Bush Keys on 26 March. The only previous records were by the tern-banding party which encountered and photo­graphed an adult and 2 immature birds during the period 9-15 May 1964 (Robertson and Mason, 1965 : 133).
• American Coot (Fulica americana)--One seen on 3 April in the moat around the fort -the fourth recorded occurrence for the islands.
• Semipalmated Plover (Charadrius semipalmatus)--This plover was seen with other shorebirds on Long Key on 28 March. Although only a few records exist for this species, Robertson and Mason (1965: 132) stated that it probably occurs more regularly than reports indicate.
• Gull-billed Tern (Gelochelidon nilotica)--Sprunt (1962: 83) listed 4 records of this species from the Tortugas. Our sighting on 30 March provides the fifth.
• Mourning Dove (Zenaidura macroura)--This species was first re­ported to have nested successfully at the Tortugas in 1962 (Robertson and Mason, 1965: 134). Our observations of incubating birds (25 March-4 April) represent the earliest breeding dates on Tortugas. Perhaps this species has an extended breeding season on these islands.
• Cliff Swallow (Petrochelidon pyrrhonota)--To the 5 previous records listed by Sprunt (1962: 131) we add an individual sighted on 29 March on Garden Key.
• Solitary Vireo (Vireo solitarius)--Robertson and Mason (1965: 136) listed 4 records of this species from the Tortugas. We added a fifth on 31 March.
• House Sparrow (Passer domesticus)--Our observations on 26 March are of interest, since this presumably non-migratory species is not expected to occur at the Tortugas. Summers-Smith (1963: 118) stated that although House Sparrows in Great Britain and Europe are extremely sedentary, they do exhibit migratory tendencies. Recently, Broun ( 1972) presented evidence that House Sparrows in North America are also at least partially migratory. The female we saw arrived concurrently with many other small passerines, including such species as Parula Warbler (Parula americana), Myrtle Warbler (Dendroica coronata), Prairie Warbler (Dendroica discolor), White-eyed Vireo (Vireo griseus), Blue-gray Gnatcatcher (Polioptila caerulea), and Palm Warbler (Dendroica palmarum). We are inclined to agree with Robertson and Mason (1965: 137) who suggested that House Sparrows may become associated with foraging flocks of small passerines and continue the association when the flocks depart on migratory flights. Summers-Smith (1963: 117) also stated that House Sparrows move with other migrants.
• Savannah Sparrow (Passerculus sandwichensis)--Robertson and Mason (1965: 137) stated that this species winters commonly at the Tortugas but that it is seldom found on Garden Key where little suitable habitat exists. During our visit we considered Savannah Sparrows common on the top of Fort Jefferson, sighting them every day while we made our rounds. Perhaps their presence on Garden Key was a result of an unusually large winter population at the Tortugas or the growth of suitable or marginal habitat on top of the fort.
• Swamp Sparrow (Melospiza georgiana)--There are 2 previous records of this species from the Tortugas. A third was observed by us on 2 April 1967 on Bush Key. It allowed close approach and seemed oblivious to the activity of the tern colony, much of its activities being confined to an area close to concentrations of Brown Noddy (Anous stolidus) nests.

• Literature Cited

  • Broun, Maurice. 1972. Apparent Migratory Behavior in the House Sparrow. Auk, 89: 187-189.
  • Robertson, William B. Jr., and C. Russell Mason. 1965. Additional Bird Records from the Dry Tortugas. Fla. Nat. 38(4): 131-138
  • Sprunt, Alexander, Jr. 1962-1963. Birds of the Dry Tortugas, 1857-1961. Fla. Nat., 35: 34-40, 82-85, 129-132; 36-23-26, 52-53.
  • Summers-Smith, J. D. 1963. The House Sparow, Collins, London 269 pp.
  • Clive A. Petrovic, F. T. Stone Laboratory, The Ohio State University, Put-in-Bay, Ohio 43456 (present address: 724 Camilo Ave., Coral Gables, Fla. 33134) and James King, Jr., 13910 N.W. 5th Ave., N. Miami, Fla. 33168.