Frequency of leucism in a colony of Anoura geoffroyi (Chiroptera: Phyllostomidae) roosting in a ferruginous cave in Brazil

Registro de desorden cromático en Trachops cirrhosus (Spix, 1823) (Chiroptera: Phyllostomidae) en la Amazonia del Ecuador

Presentamos un caso de desorden cromático observado en un ejemplar de Trachops cirrhosus proveniente de bosques de tierras bajas de la Amazonía ecuatoriana. Durante el trabajo de campo, seis individuos de esta especie fueron capturados con redes de niebla en un hábitat intervenido, de los cuales, un ejemplar macho juvenil fue distinguible del resto de individuos debido a la presencia manchas blanquecinas en la región ventral, en el pecho y abdomen. Discutimos sobre los reportes previos de este tipo de trastornos pigmentarios en murciélagos de Ecuador, y en el Neotrópico, documentando el primer registro de esta especie con esta condición para el país.

Leucistic plumage as a result of progressive greying in a cryptic nocturnal bird

Leucism, broadly defined as the lack of melanin pigmentation, occurs in many animal species. Most studies on leucism and other colour aberrations are based on opportunistic observations or small cross-sectional samples, thus limiting our ability to produce reliable results and test theoretical predictions. This study combines cross-sectional and longitudinal data collected in 2016-2020 from a population of red-necked nightjars (Caprimulgus ruficollis). The goals of the study are (i) to investigate sex and age effects on partial leucism, (ii) to separate within-subject effects (progressive greying) from between-subject effects (selective disappearance), and (iii) to examine differences in body mass, structural size, and life span between leucistic and non-leucistic individuals. The probability of leucism in nightjars increased from juveniles to adults at similar rates in males and females. Our longitudinal analysis and life-span comparisons indicated a minor contribution of selective disappearance to age-related changes in leucism, but rather suggested that the loss of melanin from feathers can be attributed to progressive greying in ageing adults. Body mass and size were consistently smaller (5% and 1.5%, respectively) in leucistic than in non-leucistic nightjars, although the reason for this difference remains unclear. Our study sheds light on the sources and mechanisms of variation in leucism in natural populations and its relationship with important life-history traits, such as life span.

First report of albinism in a lactating female of the chestnut long-tongued bat Lionycteris spurrelli Thomas, 1913 (Chiroptera, Phyllostomidae)

Albinism is a genetic disorder that causes pigmentation anomalies. Even though supposedly rare in free-living mammals, cases of albinism have been reported worldwide, particularly in bats. In this article we present a new case of albinism in a Lionycteris spurrelli Thomas, 1913. The individual, observed in an Amazon region iron ore cave, in Northern Brazil, was a lactating female with a dark-brown pelage pup.