The influence of environmental variables on capybara (Hydrochoerus hydrochaeris: Rodentia, Hydrochoeridae) detectability in anthropogenic environments of southeastern Brazil

Abstract

Capybaras were monitored weekly from 1998 to 2006 by counting individuals in three anthropogenic environments (mixed agricultural fields, forest and open areas) of southeastern Brazil in order to examine the possible influence of environmental variables (temperature, humidity, wind speed, precipitation and global radiation) on the detectability of this species. There was consistent seasonality in the number of capybaras in the study area, with a specific seasonal pattern in each area. Log-linear models were fitted to the sample counts of adult capybaras separately for each sampled area, with an allowance for monthly effects, time trends and the effects of environmental variables. Log-linear models containing effects for the months of the year and a quartic time trend were highly significant. The effects of environmental variables on sample counts were different in each type of environment. As environmental variables affect capybara detectability, they should be considered in future species survey/monitoring programs.

Counting Capybaras

“…In counting capybaras, the distance to the animals can affect their detectability by observers, even on a relatively small spatial scale (i.e., <100 m) . In addition, environmental variables can affect capybara counts in different ways according to the environment (Ferraz et al 2010 ) . It is prudent to test the homogeneous detectability assumption as a hypothesis for the focused population.…”

Interação Acústica De Anuros Em Uma Poça Temporária No Município De Cruz Das Almas, Bahia

“…As modificações antrópicas no ambiente, principalmente aquelas relacionadas com a introdução de culturas agrícolas, geram problemas já que, além de diminuir a área útil aos animais, as culturas se tornam fontes acessíveis e estáveis de alimento, permitindo o aumento aparente em grupos sociais e tamanho da população de animais silvestres (FERRAZ et al, 2009;FERRAZ et al, 2010) que podem invadir ambientes agrícolas (FERRAZ et al, 2003;GIANNONI, 1996) e urbanos, causando danos às culturas e risco para a saúde humana (FERRAZ et al, 2009).…”

“…O controle da fauna é uma forma eficaz de minimizar estes problemas (CAUGHLEY e SINCLAIR 1994;FERRAZ et al, 2010). Na província de Corrientes, Argentina, o…”

EFFECT OF TEMPERATURE AND RELATIVE HUMIDITY ON THE BEHAVIOR OF CAPYBARAS (Hydrochoerus hydrochaeris) IN AN URBAN AREA

“…Thus, this intensive aquatic behavior could be due to the need for thermoregulation, since capybaras have sparse, insufficient sweat glands (approximately 10 to 12 per cm 2 ) to exercise this function (Santos et al 2005), making the animals seek to stay in the water or rest near it during the hottest period of the day. This activity pattern is an ecophysiological adaptation of the capybaras (Ferraz et al 2010).…”

“…These information in urban areas are needed both for increasing our basic understanding of the ecology of many tropical organisms and for understanding impacts of human activity on the behavior of them (Blake et al 2012). The behavior and activity pattern of mammals can be influenced by intrinsic factors, such as: sex, age (Fernandez-Duque 2004), reproductive period (Halle & Stenseth 2000), and extrinsic factors, like as lunar phases (Sábato et al 2006), photoperiod (Everts et al 2004), temperature (Ferraz et al 2010), precipitation and relative humidity (Carvalho et al 2011). Temperature, relative humidity, precipitation and solar radiation can have effects on animal behavior, as these factors are directly related to thermoregulation, energy expenditure and animal wellbeing (Takahashi et al 2009).…”