Lara, C. E. | bioRxiv Science

bioRxiv2024

Distribution, ecology, and natural history of the recently rediscovered and critically endangered Santa Marta Sabrewing

The Santa Marta Sabrewing is a critically endangered (CR) hummingbird endemic to the Sierra Nevada de Santa Marta, Colombia. Prior to 2022, there were only three documented sightings of the sabrewing since it was described in 1879, including only one record between 1946 and 2022. As a result, this "lost" species has long been one of the most poorly-known birds in Colombia. We located a resident population of Santa Marta Sabrewing along the Guatapuri River near the Chemesquemena and Guatapuri villages in July 2022, and at its type locality, San Jose, in January 2023. Based on historical data and newly-collected field observations, we assess the species status and describe aspects of its natural history and ecology. Our review indicates the species has been frequently misidentified in the past, and that to date, documented evidence of its presence is limited to five localities, almost all of them restricted to the south-eastern slope of the Sierra Nevada de Santa Marta, along the mid Guatapuri river basin. Consequently, this bird appears to represent a case of microendemism. Following IUCN criteria, our data suggest that Santa Marta Sabrewing should remain listed as CR. Field observations indicate that the species is highly associated with watercourses, where males hold year-round territories and form leks. We obtained records of males in mid-elevation habitats (1,150-1,850 m) for 16 consecutive months between July 2022 and October 2023, suggesting that the species might not be an elevational migrant, as previously speculated. More information is needed to understand the species ecology so that effective conservation actions can be designed in collaboration with the indigenous communities with which the species coexists.

ecology↗

bioRxiv2022

Genetic, vocal, and body size divergence across the Northern Peruvian Low supports two species within the Masked Flowerpiercer (Diglossa cyanea)

Populations that become genetically isolated by geographical barriers may express phenotypic divergence more strongly in some traits than in others. Even when genetic differentiation among isolated populations accumulates at a rapid rate, this may not be reflected in phenotypic differentiation. This decoupling of trait divergence from genetic divergence has been found in multiple Andean bird lineages that occupy latitudinally long, linear ranges that are fragmented by ecological and topographic barriers. One of these montane birds is Diglossa cyanea (Thraupidae; Masked Flowerpiercer), a species with a distribution bisected by valleys and lowlands. Across these dispersal barriers one finds subspecies that differ only in subtle but diagnostic phenotypic differences. We evaluated genetic and phenotypic divergence throughout its distribution and found support for two distinct lineages sharply separated by the Maranon River valley at the Northern Peruvian Low (NPL). Specifically, we found that the two populations from the opposite sides of the NPL show deep divergence in mitochondrial DNA (mtDNA; [~]6.7% uncorrected p distance, n = 122), in song structure (exclusive final notes in southern populations, n = 88), and in wing length (longer wings in the southern population, n = 364). No genetic variation or song structure was observed within the large range of the southern group (from the NPL to central Bolivia) or within all northern populations (from the NPL to Venezuela). Moreover, these two lineages are possibly paraphyletic with respect to D. caerulescens (Bluish Flowerpiercer). Our results suggest that the southern taxon, D. c. melanopis, should be recognized as a species-level taxon, distinct from a redefined D. cyanea. We highlight the need to continue amassing complementary suites of datasets from field observations and experiments, laboratory analyses, and collection-based assessments, to better characterize the evolutionary history and taxonomic diversity of Neotropical montane birds. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=184 SRC="FIGDIR/small/492535v2_ufig1.gif" ALT="Figure 1"> View larger version (69K): org.highwire.dtl.DTLVardef@199ddfborg.highwire.dtl.DTLVardef@bc8fb0org.highwire.dtl.DTLVardef@17d7da1org.highwire.dtl.DTLVardef@1c2d9e5_HPS_FORMAT_FIGEXP M_FIG C_FIG LAY SUMMARY We analyzed variation in genetics, songs, and body size among populations of a bird species of the Andean mountains (Masked Flowerpiercer) that shows relatively little plumage variation across its 3800-km long distribution from northern Venezuela to central Bolivia. We found that the Masked Flowerpiercer consists of two divergent populations separated by a deep geographic depression known as the Northern Peruvian Low (NPL) The degree of genetic divergence between them (in terms of mtDNA) is as great as between either of them and another species, the Bluish Flowerpiercer. The two populations also have distinct songs, with the song of the southern group ending with clear whistles that are completely absent in the northern group. The southern group also tend to have longer wings than do populations north of the NPL. The southern population should be treated as a separate species, Diglossa melanopis.

evolutionary biology↗