Filling the distribution gaps of two species of Accipiter Brisson , 1760 ( Aves , Accipitriformes ) in northeastern Brazil

We present new records of Gray-bellied Hawk, Accipiter poliogaster (Temminck, 1824), and Rufous-thighed Hawk, A. striatus erythronemius (Kaup, 1850), from northeastern Brazil and review the occurrence of these species in this region. While A. s. erythronemius occurs in secondary forests in the semi-arid regions of northeast Brazil, A. poliogaster seems to be associated more with mature and wet forests and not in the Caatinga scrub.


Introduction
The cosmopolitan family Accipitridae (hawks and eagles) includes 248 species, of which, 54 are threatened with extinction (Thiollay 2018).These diurnal raptors are found in all regions of the world except Antarctica and occupy practically all types of habitat, from forests to deserts and even urban areas (Brown and Amadon 1989).
The Gray-bellied Hawk (A. poliogaster) occurs from Venezuela and the Guyanas to northern Argentina, including most of Brazil (Pinto 1978, Brown and Amadon 1989, Sick 1997, Thiollay 2018).Despite its ample distribution, records are scant and localized, and few specimens are preserved in museums (Lanzer et al. 2009).This hawk inhabits humid forests, generally in lowlands to 800 m a.s.l.; however, there are records from 1,800 m a.s.l. in southeastern Brazil and 1,950 m a.s.l. in eastern Ecuador.Little is known about the behavior of this species, and it is listed as Near Threatened by Bird-Life International (2016).
The Sharp-shinned Hawk (Accipiter striatus) is one of the smallest raptors found in Brazil.It has a large, but discontinuous distribution between North America and Argentina, including northeastern, central, and southern Brazil (Sick 1997, BirdLife International 2016).The Brazilian subspecies, A. s. erythronemius (Kaup, 1850), which some authors consider to be a distinct species, Rufous-thighed Hawk, is found in a variety of forested habitats, mostly in relatively arid areas, and in semi-open areas such as arboreal savanna, as well as more humid forests, from sea-level to altitudes of approximately 1,000 m a.s.l.(White et al. 2018).
We present new records of the Rufous-thighed Hawk and the Gray-bellied Hawk from the Brazilian state of Maranhão and review the data available on the occurrence of the two species in the country's Northeast Region.

Methods
The records presented here were collected in the Inhamum Environmental Protection Area (Inhamum EPA) in the municipality of Caxias, in Maranhão, Brazil (04°53ʹ30ʺ S, 043°24ʹ53ʺ W).The Inhamum EPA covers an area of approximately 3,500 ha on the southern margin of the BR-316 federal highway.The predominant vegetation is typical of the Brazilian Cerrado savanna (sensu lato), with elements of the transition with Amazon forest in more humid areas near watercourses, and the more arid Caatinga scrub forest.

Data Resources
The data underpinning the analysis reported in this paper are deposited at GBIF, the Global Biodiversity Information Facility, http://ipt.pensoft.net/resource?r=accipiter_ne_br.
Only 3 existing records of this species from the Brazilian Northeast were identified (Fig. 3, Table 1): an adult specimen collected by F. Schwanda in August 1910, in the municipality of Humberto de Campos, Maranhão (MPEG 7408); an adult female collected in 1944 in the municipality of Ilhéus, Bahia (MZUSP 32857); and undated specimen collected in the municipality of Salvador, Bahia (SMF 14191).
In the Brazilian Northeast, this species has been recorded in the states of Alagoas, Bahia, Ceará, Paraíba, Pernambuco, and Piauí (Table 1).
Identification.Adults of the Gray-bellied Hawk were identified by the black crown and back and 3 broad, gray bars on the white-tipped tail (Bierregaard et al. 2018).Juveniles were remarkably similar to adults of Ornate Hawk-Eagle, Spizaetus ornatus (Daudin, 1800), which is distinguished from Gray-bellied Hawk by being larger and having a longer crest and fully-feathered tarsi (Bierregaard et al. 2018).The Rufous-thighed Hawk was identified by its relatively small size, slender shape, rufous thighs, and underparts with rufous barring (White et al. 2018).In addition, we compared our recordings to audio recordings available from online databases (Xeno-canto, WikiAves) in order to confirm the identifications.
The only other records from the Brazilian Northeast are 1,200 km to the south and east in the Atlantic Forest of the state of Bahia (Fig. 3).There are no records whatsoever in the arid Caatinga biome.In contrast with A. s. erythronemius, A. poliogaster appears to depend on well-stratified, mature forests.Despite being the largest and most robust Accipiter species found in the Neotropics, its shy and elusive behavior, together with its low population densities, may contribute to the relative paucity of records available for this hawk (Pinto 1952, Sick 1997).
Our new records of A. s. erythronemius extend the known geographic distribution of this species in the Cerrado biome by approximately 350 km to the north and east; the nearest previously known locality is 300 km further northeast in the Caatinga biome.The data set compiled here indicates that A. s. erythronemius is amply distributed in the Brazilian Northeast, where it has been recorded in the Atlantic Forest, Caatinga, and Cerrado biomes.This species appears to be extremely versatile in its habitat use, inhabiting primary and secondary forests, edge habitats, savannas, and even urban areas that are sufficiently wooded (Sick 1997).
Studies of the geographic distribution of species are essential for the development of effective conservation strategies, as well as supporting biogeographic and ecological research ( Piacentini et al. 2006).Occasional

Discussion
Our records of A. poliogaster are only the second and third for the state of Maranhão (for the previous record, see Table 1 and Fig. 3 #1).These extends the range in Maranhão of this species by 250 km towards the south.
occurrence records, such as those presented here and, in particular, those of rare or threatened species from poorly known regions, are fundamentally important for the understanding and conservation of biodiversity (Godoi et al. 2012).
Our new records of the 2 Accipiter species presented here contribute to the understanding of their distribution patterns in the Brazilian Northeast, and in particular, in the state of Maranhão.Further surveys of the avian fauna of this poorly studied region are required to cover the considerable gaps in the databases.
Table 1.Records of the Gray-bellied Hawk (Accipiter poliogaster) and Rufous-thighed Hawk (Accipiter striatus erythronemius) in the Brazilian Northeast.Years of records are presented in ascending order.Only the oldest voucher is presented for the same locality if more are available.American Museum of Natural History (AMNH), Carnegie Museum of Natural History (CMNH), Museu Paraense Emílio Goeldi (MPEG), Museu de Zoologia da Universidade de São Paulo (MZUSP), Forschungsinstitut Senckenberg (SMF), WikiAves (WA), Xeno-canto (XC).* Unspecified localities were georeferenced at the municipality headquarters.M = museum specimens, P = photo, S = sound record.