Biology subjects

Nason, D.

Publications and source records attributed to Nason, D..

4 recordsLinked to original sources

bioRxiv2024

Lost to science for 126 years: Indigenous Knowledge and Camera Trapping Document the Critically Endangered Black-Naped Pheasant-Pigeon Otidiphaps insularis

We combined questionnaires collecting local ecological knowledge with passive and directed camera trapping and bird surveys to scientifically document the Black-Naped Pheasant-Pigeon Otidiphaps insularis for the first time since 1896. This species is endemic to Fergusson Island, in eastern Papua New Guinea, and is New Guineas most endangered terrestrial bird species. Indigenous subsistence-based hunters who participated in this research as informants had high levels of local bird knowledge and helped direct camera trapping for one of two successful camera trap captures. Local participants also shared traditional ecological knowledge about the Black-Naped Pheasant-Pigeon, including legends, chants, and a local name for this taxon, Auwo. The scarcity of observations over the course of a month-long expedition, its obscurity to the majority of local respondents interviewed, and prevalent threats from habitat destruction and introduced alien species further support its current Red List status (CR). Our results provide a case study for leveraging local ecological knowledge in combination with standardized survey techniques and may be an especially effective strategy for determining the status of other undocumented or data-deficient species in the southwest Pacific.

ecology↗

bioRxiv2024

An ornithological survey of Fergusson Island, D'Entrecasteaux Archipelago, Papua New Guinea, reveals new island records and noteworthy natural history observations

Fergusson Island lies off the southeastern end of New Guinea and is the largest landmass in the DEntrecasteaux and Trobriand Island Endemic Bird Area. We conducted audiovisual and camera trapping surveys in eastern Fergusson in September 2022 and recorded 97 bird species, documenting breeding and vocalizations for several of the EBAs endemic taxa. Notably, we provide the first confirmed documentation of the "lost" insularis subspecies of Pheasant Pigeon Otidiphaps nobilis (often recognized as a distinct species, Black-naped Pheasant-pigeon), in 126 years, observations of eight bird species not previously recorded from Fergusson, and nesting of Goldies Bird-of-Paradise Paradisea decora and the endemic crookshanki taxon of Capped White-eye Zosterops fuscicapilla (or Oya Tabu White-eye). Our new distributional records were mostly either migratory species or species found in open habitats, highlighting the value of surveying across seasons and habitats. We summarise our results and provide comments on distributional records, breeding behaviour, and vocalizations.

ecology↗

bioRxiv2023

Impacts of mate quality on female intrasexual aggression in two sister Malurus fairywren species

In a large and ever-growing number of animal species, it is now appreciated that females use colors as a visual signal in a range of social interactions, including both courtship and territorial aggression. Yet, it remains unclear whether female color phenotypes and/or aggressive behaviors are correlated with any attributes of their mates phenotype. For example, we might expect species in which males contribute more to parental care or territorial defense to have more colorful or aggressive females. On the other hand, within species, we might expect those females mated to higher quality males to be more colorful or aggressive than those mated to lower quality males. To begin to address these possibilities, we conducted a preliminary study in two sister taxa of fairywren (Maluridae) with distinct life-history strategies and plumage dichromatism: white-shouldered fairywrens (Malurus alboscapulatus moretoni) in tropical Papua New Guinea, a species in which both males and females have ornamented plumage and jointly defend territories year-round, and red-backed fairywrens (M. melanocephalus melanocephalus) in temperate Australia, a sexually dichromatic species with ornamented males and unornamented females. At the between species level, we predicted white-shouldered fairywren females would be more aggressive in same-sex interactions than red-backed fairywrens, as both white-shouldered males contribute to year-round territorial defense, whereas territories break-down during non-breeding in red-backed fairywrens. Further, we predicted that, within species, females mated to males of higher quality would be more aggressive in simulated same-sex encounters. Between species, female white-shouldered fairywrens were more aggressive on average than female red-backed fairywrens as predicted. Within both species, indices of male quality were not related to female aggression (although there was a non-significant tendency for more aggressive female white-shouldered fairywren to have heavier mates with longer tails). These results point to a need for additional research exploring relationships between life history, female plumage, and female aggressive behaviors in a wider range of species.

ecology↗

bioRxiv2020

Testosterone induces a female ornament followed by enhanced territoriality in a tropical songbird

We know little of the proximate mechanisms underlying expression of signaling traits in female vertebrates. Across males the expression of sexual and competitive traits, including ornamentation and aggressive behavior, is often mediated by testosterone. In the White-shouldered Fairywren (Malurus alboscapulatus) of New Guinea, females of different subspecies differ in presence or absence of white shoulder patches and melanic plumage, while males are uniformly ornamented. Previous work has shown that ornamented females circulate more testosterone and exhibit more territorial aggression than do unornamented females. We investigated the degree to which testosterone regulates expression of ornamental plumage and territorial behavior by implanting free-living unornamented females with testosterone. Every testosterone-treated female produced a male-like cloacal protuberance, and 15 of 20 replaced plucked brown feathers with white shoulder patch feathers, but did not produce melanic plumage characteristic of ornamented females. Testosterone treatment did not elevate territorial behavior prior to production of the plumage ornament and exhaustion of the implant. However, females with experimentally induced ornamentation, but exhausted implants, increased the vocal components of territory defense relative to fully unornamented control and also to testosterone-implanted females. Our results suggest that testosterone induces partial acquisition of the ornamental plumage phenotype, and that ornament expression, rather than testosterone alone, results in elevated territorial behavior. Lay SummaryTestosterone regulates expression of a suite of competitive traits in male organisms and could have similar function in females. Empirical tests are needed to determine the extent to which testosterone promotes production of ornamentation and competitive behaviors in female animals. We supplemented testosterone in unornamented females of a species where naturally occurring ornamented females circulate higher testosterone and are more territorially aggressive. Implanted females produced partial ornamentation, which was followed by increased territoriality that was apparently unrelated to testosterone circulation itself.

animal behavior and cognition↗