Evidence of vertical migration in the Ipanema bat Pygoderma bilabiatum (Chiroptera: Phyllostomidae: Stenodermatinae)

Abstract

Migration is defined as a seasonal and cyclic population movement observed in all animal classes and studied mainly in vertebrates. A considerable part of the knowledge on migration comes from birds, for which migration is an important aspect of their biology. In the case of bats, females usually migrate larger distances than males in some species. The present study analyzes the seasonal occurrence of Pygoderma bilabiatum (Wagner, 1843) at different elevations, in order to test for a pattern that evidences migration, using data from the states of Espírito Santo, Minas Gerais, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul, Brazil. A total of 529 specimens of P. bilabiatum were captured. Pygoderma bilabiatum seems to be more frequent at intermediate and high elevations (over 80% of all captures were made above 250 m a.s.l.) and at latitudes above 22°S, where rainfall is high (over 1,500 mm) and temperatures are mild (16-23°C). Sex ratio varied with elevation; it was skewed towards males at lower elevations (N = 9, r² = 0.60, F = 12.311, p = 0.008, Sex ratio = 0.0004*elevation + 0.976), though females predominated at all altitudinal bands and in all states analyzed

Population Composition and Ectoparasite Prevalence on Bats (Sturnira ludovici; Phyllostomidae) in Forest Fragments and Coffee Plantations of Central Veracruz, Mexico

“…, Esbérard et al . ). Based on this, we suggest that in our study, more females were found in forest fragment landscapes because of the higher density of resource plants in this habitat (Saldaña‐Vázquez et al .…”

“…As females are present year-round in cloud forest, the abundance is skewed toward females when the males have migrated. Significant differences in sex proportions have been reported in other species of phyllostomids such as Artibeus jamaicensis, Anoura geoffroyi, Glossophaga soricina, Pygoderma bilabiatum, and Carollia perspicillata, possibly due to seasonal and altitude variations in food resources (Stoner 2001, Zortea 2003, Mello et al 2004, Esbérard et al 2011. Based on this, we suggest that in our study, more females were found in forest fragment landscapes because of the higher density of resource plants in this habitat (Saldaña-Vázquez et al 2010), whereas the males either migrated during parts of the year, or used the marginal habitat found in coffee plantations to avoid competition with females.…”

Long-distance movement by a great fruit-eating bat, Artibeus lituratus (Olfers, 1818), in southeastern Brazil (Chiroptera, Phyllostomidae): evidence for migration in Neotropical bats?

“…This author suggested that the increase was caused by migration of some individuals to the region, because in this season temperature was warmer in lower altitudes and more food would be available when compared to highlands. Some years ago, Esberard et al (2011) gathered data on extensive year-round sampling at multiple elevations to test for evidence of altitudinal migration in Ipanema broad-nosed bats, Pygoderma bilabiatum (Wagner, 1843). P. bilabiatum was absent in regions where the temperature varied seasonally, and less common during cooler seasons at higher elevations.…”

Principles and Patterns of Bat Movements: From Aerodynamics to Ecology

“…The feeding preferences of frugivorous bats seem to influence their foraging decisions even within a population as, for instance, individual Sturnira lilium differ in the fruit genera they prefer (Muylaert et al 2014), and consequently differ also in the main habitats they use, depending on the availability of different edible fruits. Novel evidence points out that nomadism and migration may be influenced by flower and fruit availability in some phyllostomid bats, such as Pygoderma bilabiatum (Esbérard et al 2011) and Sturnira lilium (Mello et al 2008). In summary, a combination of dietary specialization, plant phenology (e.g., unpredictable fluctuations), plant distribution (e.g., patchiness), and climate seasonality appears key to understanding the movement ecology of these and other phytophagous bats.…”