Puerto Rican Broad-winged Hawk

Buteo platypterus brunnescens

Description

The Buteo platypterus brunnescens (Puerto Rican broad-winged hawk) is a dark chocolate brown, small-size hawk that measures approximately 15.5 in (39 cm). It is smaller than the Buteo platypterus platypterus but larger than the Lesser Antillean sub-species. This is the darkest subspecies of the broad-winged hawk. In adults, the tail, broadly banded with black and white, and the rufous breast are characteristic. Immature birds have dark bars on the breast and lack the distinctive tail bands of the adult. Broadwings flap more than the similar but larger red-tailed hawk.

Behavior

Knowledge of the biology of the Puerto Rican broad-winged hawk is limited. Food-habit studies were conducted on one of the three nests found in the Caribbean National Forest in 1976 and one nest found in Rio Abajo in 1978. The prey types taken included centipedes, frogs, lizards, mice, rats, and birds (as large as 7 oz or 200 g). Studies of breeding biology, habitat requirements and other aspects of this species' biology are not available in the literature.

Habitat

The Puerto Rican broad-winged hawk is an uncommon and extremely local resident. Extant populations are restricted to montane habitats of three forests: Rio Abajo Commonwealth Forest, Carite Commonwealth Forest and Caribbean National Forest. Breeding has not been documented in the Carite forest. The observed individuals were observed to be clustered in the north-central part of the forest within the subtropical wet forest and subtropical rain forest life zones, where the tabonuco is the dominant forest type. Information received from the U.S. Fish and Wildlife Service's Puerto Rican Parrot Field Office states that broad-winged hawks have been sighted in several watersheds throughout the forest (e.g. Mameyes, Sonadora, Espiritu Santo, and Quebrada Grande) besides the north-central ridge. The field office also mentioned that estimates for the Caribbean National Forest may be underestimated due to limited access to the interior regions of the Forest.

Distribution

The Puerto Rican broad-winged hawk was first reported in Puerto Rico in 1878. He reported this species as "common" in the "interior" of Puerto Rico, and in 1883 it was reported as "transient". In the first half of the 20th century, the species was not observed, and in 1927 it was believed to have become extinct. A specimen was collected in 1935 in Luquillo (Caribbean National Forest) and described it as a distinct resident subspecies, the Puerto Rican broad-winged hawk (Buteo platypterus brunnescens ). Sightings were reported again in 1936 and 1963 from the Luquillo, Utuado and Maricao forests.

In the mid 1980s, the population in the Caribbean National Forest was estimated to be 40-60 individuals and 15-20 breeding pairs. The broad-winged hawks were more often seen in the eastern side of the Caribbean National Forest, and the tabonuco and Palo Colorado forest types were reported to be the preferred habitats for the species. In 1992, 12 broad-winged hawks were sighted in the Caribbean National Forest and the population was estimated at 22 individuals.

Very little is known about the Rio Abajo and Carite forest populations. However, it appears that the existence of the Rio Abajo population was known in 1936 and 1963. In 1987 it was believed that the Rio Abajo forest sustained not more than 50 individuals. In 1992, 26 broad-winged hawks, or an estimated population of 52 individuals, were reported in the Rio Abajo forest. The Puerto Rican broad-winged hawk was unknown from the Carite forest until 1980, when the existence of a resident population present year-round was reported. In 1992, 20 broad-winged hawks were censused in the Carite forest and a population of 22 individuals was estimated. In the Carite forest the species has been reported from the elfin, caimitillo, granadillo, tabonuco, and slope forest types.

A 1992 census of 80 sq mi three forests (Rio Abajo, Carite and Caribbean National Forest) yielded 58 broad-winged hawks or an estimated population of 124 individuals. Sightings of the broad-winged hawk have been reported from other areas, such as Cayey (next to the Carite forest), Utuado, Jayuya, Adjuntas, Villalba, and the Maricao and Toro Negro but it has been established that the Maricao and Toro Negro forests do not have resident populations. Broad-winged hawks have been searched for, but not sighted, in upland forested habitats in Utuado, Jayuya, Adjuntas, Orocovis, and Barranquitas as of 1992.

Threats

Increased pressure for new right-of-way access to farms through the Carite forest land and the establishment of new communication facilities could also destroy prime habitat or bring human activities too close to broad-winged hawks, as with the destruction of substantial caimitillo-granadillo habitat occurred in the right-of-way-access through Camino El Seis in the north-central part of the Carite forest. A new communication facilities along an access road through sector Farallon in the northwestern part of the forest is located where the highest broad-winged hawk densities have been reported.

The Puerto Rican broad-winged hawk populations are extremely small and limited to only three montane forests. Significant adverse effects to this species or its habitat could drive it to extinction. The potential for illegal shooting, increased human disturbance and loss of prime habitat in the forests constitute serious threats to the continued survival of the species.

Conservation and Recovery

The U.S. Fish and Wildlife Service published a Recovery Plan for the Puerto Rican broad-winged hawk in 1997. It only survives in the Rio Abajo and Carite Commonwealth Forests (managed by the Commonwealth of Puerto Rico), and in the Caribbean National Forest (U.S. Forest Service). Its survival is absolutely dependent on the protection of its habitat in these areas of remnant montane forest. This can be accomplished by conserving these forests against destructive uses in forestry, road-building, and other threatening developments. In addition, the endangered hawk must be strictly protected against any shooting. The populations of the Puerto Rican broad-winged hawk should be monitored, and research undertaken into its biology and habitat needs.

Contacts

U. S. Fish and Wildlife Service
Boqueron Ecological Services Field Office
P.O. Box 491
Boqueron, Puerto Rico 00622
Telephone: (809) 851-7297

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

References

U.S. Fish and Wildlife Service. 9 Sept. 1994. "Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for the Puerto Rican Broad-Winged Hawk and the Puerto Rican Sharp-Shinned Hawk." Federal Register http://endangered.fws.gov/r/fr94550.html

U.S. Fish and Wildlife Service. 1997. "Puerto Rican Broad-winged Hawk and Puerto Rican Sharp-shinned Hawk Recovery Plan." U.S. Fish and Wildlife Service, Atlanta, Georgia.