Puerto Rican Sharp-shinned Hawk
Encyclopedia
The Puerto Rican Sharp-shinned Hawk, (Accipiter striatus venator), Falcon de Sierra or Gavilán pecho rufo in Spanish, is an endemic subspecies of the North American Sharp-shinned Hawk
, occurring only in Puerto Rico
. Discovered in 1912 and described as a distinct sub-species, it has been placed on the United States Fish and Wildlife Service list of endangered species
because of its rapidly dwindling population on the archipelago of Puerto Rico.
, with the female almost 50% larger than the male. This allows each sex to focus their predatory efforts on different sized prey.
s to hummingbird
s. It requires a home range of approximately 150 hectares (370 acres). Females lay two to three white eggs in March or April and incubate them while the male searches for food. Average incubation period is approximately 32 days. Fledglings leave the nest 30 days after hatching.
larvae, warble fly
larvae, and nest predation by the Pearly-eyed Thrasher
(Margarops fuscatus) have also contributed to its population reduction. Although an overall population of 129 birds has been reported on the island (Delannoy, 1992), in El Yunque National Forest
, the only two sharp-shinned hawks sighted at that time were a solitary territorial pair that were sighted in the south-central part of the forest.
remain at their nesting sites permanently. Both males and females become more active in the nest building process one month before eggs are laid. Egg laying usually occurs during March and April and a second clutch may be laid rarely from May to July. Second clutches are only laid in the event the first brood of eggs is lost. Typical incubation periods last for one month. Nesting period ends once the juveniles fly short distances from the nest and roost in trees 10 to 15 meters (32 to 48 ft) from the nest. More than half of fledging failures are caused by warble fly larvae.
s and territorial flights. Both the males and females partake in courtship displays which typically last from sunrise until mid-morning. In February, females stop foraging and remain near the nesting site. Only the female provides incubation and the role of the male is to provide all food to the female.
s, 100 grams (4 oz) are taken with some regularity.
Sharp-shinned Hawk
The Sharp-shinned Hawk is a small hawk. In fact, "sharp-shins" or "sharpies" are the smallest to reside in USA and Canada, though some Neotropical species are smaller...
, occurring only in Puerto Rico
Fauna of Puerto Rico
The fauna of Puerto Rico is similar to other island archipelago faunas, with high endemism, and low, skewed taxonomic diversity. Bats are the only extant native terrestrial mammals in Puerto Rico. All other terrestrial mammals in the area were introduced by humans, and include species such as cats,...
. Discovered in 1912 and described as a distinct sub-species, it has been placed on the United States Fish and Wildlife Service list of endangered species
United States Fish and Wildlife Service list of endangered species
This list contains only the bird and mammal species described as endangered by the United States Fish and Wildlife Service. It contains species not only in the U.S. and its territories, but also species only found abroad. It does not contain fish, amphibians, reptiles, plants, or invertebrates,...
because of its rapidly dwindling population on the archipelago of Puerto Rico.
Description
The Puerto Rican Sharp-shinned Hawk is a small forest hawk measuring approximately 28–33 cm (11–13 in). It has a dark blue/slate gray upper area with reddish-orange stripes on its breast. Immature birds have a brownish hue above and are striped below. It has broad wings and a proportionally long, squared-off tail, enabling it to turn and maneuver rapidly when chasing small birds through the forest canopy. The subspecies shows characteristics of sexual dimorphismSexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
, with the female almost 50% larger than the male. This allows each sex to focus their predatory efforts on different sized prey.
Behavior
The Puerto Rican sharp-shinned Hawk feeds primarily on small birds ranging in size from tanagerTanager
The tanagers comprise the bird family Thraupidae, in the order Passeriformes. The family has an American distribution.There were traditionally about 240 species of tanagers, but the taxonomic treatment of this family's members is currently in a state of flux...
s to hummingbird
Hummingbird
Hummingbirds are birds that comprise the family Trochilidae. They are among the smallest of birds, most species measuring in the 7.5–13 cm range. Indeed, the smallest extant bird species is a hummingbird, the 5-cm Bee Hummingbird. They can hover in mid-air by rapidly flapping their wings...
s. It requires a home range of approximately 150 hectares (370 acres). Females lay two to three white eggs in March or April and incubate them while the male searches for food. Average incubation period is approximately 32 days. Fledglings leave the nest 30 days after hatching.
Distribution
Restricted to five isolated mountain forest areas within the subtropical lower mountain wet forests and subtropical wet forest life zones of the main island of Puerto Rico, the subspecies has suffered a 40% decline in population since 1992. As of 1997, its estimated population is approximately 150 birds. Human causes in population decline are from deforestation due to road construction, power lines, and communications facilities installations which have significantly reduced its habitat area. Natural disasters such as hurricanes also contribute significantly to population declines. Nest failures due to fledgling infestation with botflyBotfly
A botfly is any fly in the family Oestridae, which includes all the members of the former families Cuterebridae, Gasterophilidae, and Hypodermatidae. It is the only family of flies whose larvae live as obligate parasites within the bodies of mammals, with the exception of a few screwworm flies in...
larvae, warble fly
Warble fly
Warble fly is a name given to the genus Hypoderma, large flies which are parasitic on cattle and deer. Other names include "heel flies", "bomb flies", and "gad flies", while their larvae are often called "cattle grubs" or "wolves." Common species of warble fly include Hypoderma lineatum , Hypoderma...
larvae, and nest predation by the Pearly-eyed Thrasher
Pearly-eyed Thrasher
The Pearly-eyed Thrasher is a bird found in Puerto Rico and the Virgin Islands, the Bahamas and Antilles. Its genus, Margarops, is considered monotypic today; formerly the Scaly-breasted Thrasher was placed here too...
(Margarops fuscatus) have also contributed to its population reduction. Although an overall population of 129 birds has been reported on the island (Delannoy, 1992), in El Yunque National Forest
El Yunque National Forest
El Yunque National Forest, formerly known as the Luquillo National Forest, and the Caribbean National Forest, is a forest located in northeastern Puerto Rico. It is the only tropical rain forest in the United States...
, the only two sharp-shinned hawks sighted at that time were a solitary territorial pair that were sighted in the south-central part of the forest.
Nesting
Puerto Rican Sharp-shinned Hawks select plantation and natural forest nest sites with similar vegetative structure and mountainous topography. Closed canopies and dense vegetation are sought by the hawks in the selection of nesting sites. They place their platform nests below the canopy on horizontal branches usually against the trunk or in crotches away from the trunk. Construction of nesting platforms usually begin in January after a breeding pairBreeding pair
Breeding pair is a pair of animals which cooperate over time to produce offspring with some form of a bond between the individuals. For example, many birds mate for a breeding season or sometimes for life. They may share some or all of the tasks involved: building a nest, incubating the eggs and...
remain at their nesting sites permanently. Both males and females become more active in the nest building process one month before eggs are laid. Egg laying usually occurs during March and April and a second clutch may be laid rarely from May to July. Second clutches are only laid in the event the first brood of eggs is lost. Typical incubation periods last for one month. Nesting period ends once the juveniles fly short distances from the nest and roost in trees 10 to 15 meters (32 to 48 ft) from the nest. More than half of fledging failures are caused by warble fly larvae.
Courtship and foraging
Most activity during early occupancy of nesting sites consisted of courtship displayCourtship display
Courtship display is a special, sometimes ritualised, set of behaviours which some animals perform as part of courtship. Courtship behaviours can include special calls, postures, and movements, and may involve special plumage, bright colours or other ornamentation. A good example is the 'dancing'...
s and territorial flights. Both the males and females partake in courtship displays which typically last from sunrise until mid-morning. In February, females stop foraging and remain near the nesting site. Only the female provides incubation and the role of the male is to provide all food to the female.
Diet
The Puerto Rican Sharp-shinned Hawk's diet consists predominantly of small birds the size of tanagers, 30 grams (1 oz) or smaller. Due to the larger size of the female, it is possible that some thrasherThrasher
Thrashers are a New World group of passerine birds related to mockingbirds and New World catbirds. Like these, they are in the Mimidae family. There are 15 species in one large and 4 monotypic genera.These do not form a clade but are a phenetic assemblage...
s, 100 grams (4 oz) are taken with some regularity.
See also
- Birds of Puerto Rico
- Fauna of Puerto RicoFauna of Puerto RicoThe fauna of Puerto Rico is similar to other island archipelago faunas, with high endemism, and low, skewed taxonomic diversity. Bats are the only extant native terrestrial mammals in Puerto Rico. All other terrestrial mammals in the area were introduced by humans, and include species such as cats,...
- List of endemic fauna of Puerto Rico