Taxonomy, natural history, and conservation of the Great-billed Seed-Finch Sporophila maximiliani (Cabanis, 1851) (Thraupidae, Sporophilinae)

Abstract

Seed-finches are small-sized Neotropical granivorous birds characterized by extremely strong and thick beaks. Among these birds, the Great-billed Seed-Finch Sporophila maximiliani has been selectively and intensively trapped to the extent that has become one of the most endangered bird species in South America, yet its taxonomy remains complex and controversial. Two subspecies have been recognized: S. m. maximiliani (Cabanis, 1851), mainly from the Cerrado of central South America, and S. m. parkesi Olson (= Oryzoborus m. magnirostris), from northeastern South America. Originally, S. m. parkesi was diagnosed as being larger than the Large-billed Seed-Finch, S. c. crassirostris (Gmelin, 1789), but proper comparisons with S. m. maximiliani, which is larger than S. c. crassirostris, were never performed. Here we provide a review of the taxonomic and nomenclatural history of S. maximiliani, reevaluate the validity and taxonomic status of the subspecies based on morphological characters, and significantly revise its geographic distribution. Analyses based on plumage patterns and a Principal Component Analysis of morphometric characters indicated that S. m. parkesi is most appropriately treated as a synonym of the nominate taxon, which results in a monotypic S. maximiliani comprising two disjunct populations. Further, we conducted systematic searches for S. maximiliani in Brazil, in an attempt to obtain natural history information. After more than 6,000 hours of fieldwork in 45 areas of potential and historical occurrence, S. maximiliani was located only in two sites, in marshy environments called veredas, confirming the critical conservation status of this species, at least in Brazil. We discuss the conservation potential for, and the problems involved with, captive breeding of S. maximiliani for reintroduction into the wild.

Quantitative genetic analyses provide parameters for selection and conservation of captive Great-billed Seed-finches (Sporophila maximiliani)

“…Even though kept in the relatively controlled environment of the aviaries in terms of nutrition and management, the breeding period of captive Great-billed Seed-Finches was similar to that observed for free-living individuals between November and March, spring and summer in the south hemisphere [ 1 , 50 ]. Since most breeders keep their birds under natural lighting, photoperiod seems to be one of the major factors determining the breeding of Great-billed Seed-Finches under captivity.…”

“…For the first time, a trait related to singing and territorialism of Great-billed Seed-Finches was defined and evaluated, which was called STT. As stated earlier, Great-billed Seed-Finches are territorial birds [ 1 ], which during male-male competition events encourage them to sing. The total time that a bird sings within a predetermined period has been used as the primary criterion for the empirical selection of most captive Great-billed Seed-Finches.…”

“…The mating of Great-billed Seed-finches is a crucial point in stimulating male-male competition. In the reproductive period, these birds become extremely territorial and aggressive [ 1 ]. The female of each male, also individually caged, accompanied his mate until the tournament began.…”

“…The Great-billed Seed-finch ( Sporophila maximiliani ) is a South American bird, occurring mainly in flooded areas and marshy borders in the Brazilian Cerrado biome [ 1 ]. This little bird has suffered from trafficking and the destruction of its natural habitat.…”

“…This little bird has suffered from trafficking and the destruction of its natural habitat. Currently, Great-billed Seed-finch is rarely found in nature [ 1 ] and is therefore regarded as endangered by the International Union for Conservation [ 2 ] and as critically endangered by the Brazilian government (ICMBio-MMA, 2018). Probably due to the small number of free individuals, records of trafficking of Great-billed Seed-finches today have been relatively rare [ 3 – 6 ].…”