Range and conservation of the regionally Critically Endangered Black-collared Swallow, Pygochelidon melanoleuca (Wied, 1820) (Aves, Hirundinidae), in Minas Gerais, Brazil

The Black-collared Swallow, Pygochelidon melanoleuca, is a Critically Endangered species in the state of Minas Gerais, Brazil, where its distribution remains poorly known. Here we present novel occurrence records in the Paranaíba, São Francisco and Jequitinhonha river basins, and we discuss the conservation of this species in the region.

Although P. melanoleuca is globally classified as Least Concern (BirdLife International 2016), it is considered Near Threatened in Brazil (criterion A3c; MMA 2015), and Critically Endangered in the state of Minas Gerais (criterion A3c; Drummond et al. 2008;COPAM 2010).The main threat to this species is habitat loss due to the installation of hydroelectric dams (Drummond et al. 2008, MMA 2015, Lees et al. 2016).Here, we provide

NOTES ON GEOGRAPHIC DISTRIBUTION
new distributional data for P. melanoleuca in Minas Gerais, where it is known to date from only a few records in the Paranaíba river basin (Drummond et al. 2008).Based on our findings we discuss perspectives for its conservation in this region.

Methods
To update the range of P. melanoleuca in Minas Gerais, we compiled recent records collected by ourselves and those obtained by personal communications with other ornithologists.We also gathered records from grey and published literature and ornithological collections, namely, the Instituto Nacional de Pesquisas da Amazônia (INPA), Museu Paraense Emílio Goeldi (MPEG), Museu de Zoologia of the Universidade de São Paulo (MZUSP), Museu Nacional do Rio de Janeiro (MNRJ) and Centro de Coleções Taxonômicas of the Universidade Federal de Minas Gerais (DZUFMG).We also compiled records available on the following online databases: WikiAves (http://www.wikiaves.com.br/),GBIF (http://www.gbif.org/)and SpeciesLink (http://splink.cria.org.br/).Finally, we plotted all records on a map of Minas Gerais, alongside existing hydroelectric dams and the ones in the planning stage based on information from the Brazilian Ministry of Mines and Energy (Brasil/Sigel 2011).Details on each record are provided in Table 1.

Results
According to Turner (2016), P. melanoleuca (Fig. 1) may be identified as about 15 cm and 11 g, presenting deeply forked tail, glossy blue-black crown and upperparts, black wings and tail, white underparts, with blue-black breastband and blue-black undertail coverts.
We recorded P. melanoleuca at 17 sites in Minas Gerais (Fig. 2).In the São Francisco river basin, new records were obtained in Abaeté, Paraopeba, Santo Antônio and Pará rivers.In Abaeté River, we recorded the species at 7 distinct localities in the municipality of São Gonçalo do Abaeté (18°05ʹ55ʺ S, 045°25ʹ27ʺ W).On the Paraopeba River, 1 individual was observed upstream of the Retiro
In the Jequitinhonha river basin, records of P. mela noleuca are scarce and restricted to the river's main channel in the municipality of Almenara (16°25ʹ59ʺ S, 040°58ʹ59ʺ W), where 4 individuals were observed in 2005 (F.Pacheco pers.comm.), and several others were recorded under a bridge between the city of Almenara and a federal road (BR-367) in January 2015 and October 2016 (16°11ʹ12ʺ S, 040°41ʹ44ʺ W).
In the Paranaíba river basin, P. melanoleuca was recorded from September to November 2009 (Cemig/ Neoinvest 2012) and September 2013 along the central section of the Paranaíba River on the border of the states of Minas Gerais and Goiás (18°10ʹ10ʺ S, 047°27ʹ35ʺ W; 18°12ʹ56ʺ S, 047°34ʹ08ʺ W).Until recently P. melano leuca was only known in Minas Gerais from the Araguari river basin, which is part of the Paranaíba river basin (Barros 2008, Drummond et al. 2008).In July and August 2005 and from February to May and September to December 2006, we observed the species along several lotic sections of the Araguari River on the border of the Uberlândia and Araguari municipalities.In April and November 2006, 150 individuals were observed roosting under a railway bridge of the Araguari River (Table 1).However, in March and October 2012 no individuals were observed at the same lotic sections and the roosting site.At same period some individuals were observed in the residual flow river stretch, that is, the river stretch between dam and powerhouse, of the Amador Aguiar I Hydroeletric Power Plant.

Discussion
All river basins in which new records of P. melanoleuca were obtained were previously visited by ornithologists but there were no previous records of this species for these sites (e.g., Kirwan et al. 2001, 2004, Vasconcelos and Silva 2004, Vasconcelos et al. 2004, 2005, Vasconcelos and D'Angelo Neto 2007, Silveira 2009, Diniz et al. 2012, Schunck et al. 2012, Carrara et al. 2013).This lack of previous records might either reflect recent range expansion or undersampling of the specific microhabitats, rarely visited by ornithologists, required by this species.Thus, unless the exact river sections with suitable and well preserved microhabitats used by P. melanoleuca are visited, the chances of recording the species are low.
Most of the river basins where the species occurs in Minas Gerais are considered suitable for hydroelectric dam construction, which represents a major long-term threat.The construction of hydroelectric dams will likely flood rocky outcrops that are required by this species (Batista et al. 2012, Lees et al. 2016) and likely lead to local extinctions.In the upper portion of the Paranaíba basin (specifically on the Paranaíba and São Marcos rivers) 4 new dams are planned for a near future (ANEEL 2003(ANEEL , 2004)).In the São Francisco basin, all rivers mentioned here (i.e., Abaeté, Santo Antônio, Pará and Paraopeba rivers) have dams under construction or already complete.In the Jequitinhonha basin, 7 new dams are expected to be built on the main river channel (Fig. 2).
The river sections targeted for dam constructions often present steep fluvial gradients and rapids which are the main habitat of P. melanoleuca.Thus, the construction of additional dams may likely lead to dramatic declines of these recently discovered populations, as has potentially happened on the Araguari River with the implementation of 2 dams (Biovet 2012).Currently there are approximately 136 hydropower plants in the state of Minas Gerais (ANA 2016), and another 45 new large hydroelectric ("Usina Hidrelétrica" or "UHE", in Portuguese) and 335 new small hydropower plants ("Pequena Central Hidrelétrica" or "PCH", in Portuguese) are expected to be built in this state in the next 20 years, encompassing 8 river basins, including the São Francisco, Paranaíba and Jequitinhonha Rivers (SEMAD 2007).Importantly, in most cases the hydroelectric projects are licensed and assessed individually, neglecting cumulative negative effects of multiple dams built in the same river on the biodiversity.In this context, the implementation of such individual dams is commonly considered as "low impact" despite the lack of investigation of such cumulative impacts.A comprehensive analysis of the impacts should take into account the entire river basin in order to better understand and forecast the extent of the effects of multiple dams on animal populations.Such comprehensive studies would allow more effective mitigation or compensatory measures (MMA 2006, Lees et al. 2016), such as the establishment of dam-free river sections.
In summary, the records compiled here increase the known range of P. melanoleuca in Minas Gerais.Previous knowledge gaps are likely explained by the patchy distribution of the species as well as lack of sampling on the species habitat.We expect further field surveys to reveal other populations, especially in other tributaries of São Francisco, Paranaíba and Jequitinhonha rivers and also in other river basins where even the main channel remain poorly sampled, like the Mucuri River.We also encourage research on the basic ecology of the species and the potential effects of dams its population viability.

Figure 2 .
Figure 2. New (red) and previous (green circles) of Pygochelidon melanoleuca (Black-collared Swallow) from the state of Minas Gerais.Existing (black triangle) and planned dams (white triangle) according to Brasil/Sigel (2011) are also shown.