Sharp-shinned Hawk (Accipiter striatus)

Sharp-shinned Hawk

Description

The sharp-shinned hawk (Accipiter striatus) is a small hawk, with males being the smallest hawks in the United States and Canada, but with the species averaging larger than some Neotropical species, such as the tiny hawk. The taxonomy is far from resolved, with some authorities considering the southern taxa to represent three separate species: white-breasted hawk (A. chionogaster), plain-breasted hawk (A. ventralis), and rufous-thighed hawk (A. erythronemius). The American Ornithological Society keeps all four species conspecific. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (April 2016) (Learn how and when to remove this template message)

Distribution And Habitat

The Sharp-shinned Hawk occurs through North, Central, and South America (Biaggi 1997, Raffaele and others 1998) including the West Indies, where it is a common year- round resident on Cuba and Hispaniola, and rare on Puerto Rico (Raffaele and others 1998). The Puerto Rican Sharp- shinned Hawk (A. s. venator) is an endangered breeding resident subspecies found in the montane forests and shade coffee plantations of Puerto Rico (Delannoy 1992). Historically, the species bred in the Sierra de Cayey, Sierra de Luquillo, and the central west portion of the Cordillera Central (e.g., Maricao forest) mostly above 400 m elevation (Delannoy and Cruz 1999, Oberle 2018). However, recent surveys indicate that the species has declined in population (especially in Maricao) and distribution, and is now believed to be isolated in a few montane forests (Delannoy 1992, Gallardo and Vilella 2014). A single individual was observed on Mona in 1972 and considered vagrant (Terborgh and Faaborg 1973). The atlas fieldwork yielded a total of 20 records within eight hexagons or 2 percent of the 479 total hexagons (see map). Of the eight hexagons where this species was found, breeding met the atlas definition of confirmed in 38 percent (three) of the hexagons, probable in 13 percent (one), and possible in 50 percent (four) (see map).Sharp-shinned Hawk distribution. The map shows the highest breeding code by hexagon and overlaying the ecological life zones in Puerto Rico. Note: percentages may not total 100 due to rounding. 169Sharp-shinned Hawk/Halcón o Gavilán de Sierra

Breeding Habits

Previously published reports indicate that the Sharp-shinned Hawk breeds from March to June (Delannoy and Cruz 1988, Raffaele and others 1998). The nest is a platform made of twigs built high in a tree or palm (Delannoy and Cruz 1988, Raffaele and others 1998). Atlas results show that this species breeds mostly from November to June and also during August, with the most breeding activity during February to April (see chart). Overall, the breeding activity peaks in March and mostly takes place within subtropical wet forest life zones (see chart). Results show that this species breeds mostly within subtropical wet and lower montane wet forest life zones (63 percent of the hexagons), but it also breeds in the subtropical moist forest life zone (25 percent of the hexagons) and may also breed within the subtropical dry forest life zone (13 percent of the hexagons) (see table and map).

Conservation

The current population trend of the Sharp-shinned Hawk is described as increasing in North America (Butcher and Niven 2007), and it is currently listed as a species of least concern by the IUCN (BirdLife International 2016). Nonetheless, the Puerto Rican subspecies (A. s. venator) is critically endangered (PRDNER 2016) and is included on the Federal Endangered Species List (USFWS 1973) as it has declined dramatically in the Sierra de Luquillo and Carite forests, mostly due to hurricanes, introduced predators, egg/ chick predation by the Pearly- eyed Thrasher (Margarops fuscatus), and nest failures due to fl edglings infested with botfl y larvae (Philornis spp.) (Delannoy 1992; Gallardo and Vilella 2014, 2017; Oberle 2018). In Puerto Rico, the Sharp-shinned Hawk has a protected habitat in land of 26 percent or 49 km2 of the total area covered by the hexagons where evidence of breeding was found for this species (191 km2).