Microhabitat use by three species of egret (Pelecaniformes, Ardeidae) in southern Brazil

Abstract

In the present study, we examined the role of different habitat components and their relationship with microhabitat use by three species of egret: Cocoi heron (Ardea cocoi), Great egret (Ardea alba), and Cattle egret (Bubulcus ibis), in wetlands of southern Brazil. Ardea alba and A. cocoi were not habitat-specific (e.g. vegetation cover and flooding level). Conversely, B. ibis was associated with drier microhabitats. Relative air humidity and air temperature were the main variables which correlated with the occurrence of these species and supported the plasticity of B. ibis and its predominance in drier habitats.Keywords: Aquatic birds, marsh, habitat, Taim. Uso de micro-habitat por três espécies de garça (Pelecaniformes, Ardeidae) no sul do Brasil ResumoNo presente estudo foi avaliado o papel de diferentes componentes do habitat e sua relação quanto ao uso do microambiente por três espécies de Ardeidae: garça-moura (Ardea cocoi), garça-branca-grande (Ardea alba) e garça-vaqueira (Bubulcus ibis), em banhados do extremo sul brasileiro. Aparentemente, A. alba e A. cocoi não apresentaram especificidade a algum tipo de habitat (e.g. cobertura vegetal e nível de alagamento). Por outro lado B. ibis revelou associações a microambientes mais secos. A temperatura do ar e umidade relativa do ar foram as principais variáveis correlacionadas com a ocorrência dessas espécies, além disso, reforçou-se a plasticidade de B. ibis e sua predominância em ambientes secos.

Genetic structuring among populations of the great egret, Ardea alba egretta, in major Brazilian wetlands

“…This is alarming, as previous studies on foraging ecology (Gimenes and Anjos, ), microhabitat use (Pinto et al ., ) and breeding behaviour (Nunes and Tomas, ; Scherer et al ., ) have shown that the great egret in Brazil tends to occupy regions with very specific abiotic characteristics. In southern Brazilian wetlands, for example, the presence of this species is influenced by precise air temperature and relative humidity levels, which affect foraging patterns due to reduced prey availability on hotter days (Pinto et al ., ). Thus, changes in the major environmental variables of the wetlands used by the great egret are likely to exert an influence on population dynamics.…”

“…Although this species is globally listed as ‘least concern’ by the International Union for Conservation of Nature (IUCN, ), with trends indicating increasing populations (Morales, ), it is increasingly affected by the many threats to the wetlands in which it forages, roosts and breeds. This is alarming, as previous studies on foraging ecology (Gimenes and Anjos, ), microhabitat use (Pinto et al ., ) and breeding behaviour (Nunes and Tomas, ; Scherer et al ., ) have shown that the great egret in Brazil tends to occupy regions with very specific abiotic characteristics. In southern Brazilian wetlands, for example, the presence of this species is influenced by precise air temperature and relative humidity levels, which affect foraging patterns due to reduced prey availability on hotter days (Pinto et al ., ).…”

“…Great egrets can travel large distances, which can lead to gene flow between populations from different regions (i.e. homogenization of allele frequencies) but, at the same time, they occupy particular breeding sites annually for many years (Ogden et al ., ; Bancroft et al ., ; Pinto et al ., ). Hence, we expected that populations distributed throughout the country may show some degree of significant genetic differentiation.…”

Richness, abundance and microhabitat use by Ardeidae (Aves: Pelecaniformes) during one seasonal cycle in the floodplain lakesof the lower Amazon River

“…According to Gimenes and Anjos (2011), A. cocoi, A. alba and T. lineatum did not demonstrate a clear preference for a particular habitat of the Paraná River, whereas Pinto et al (2013) reported that A. cocoi and A. alba used similar substrates in the presence or absence of water. This results differ from ours, since in our data these species showed preference for aquatic macrophytes in the four phases of the seasonal cycle.…”

“…However, the use of habitats by these birds can vary considerably according to their degree of specialization (Dimalexis et al 1997, Bancroft et al 2002, Isacch and Martínez 2003. While some species use various types of habitats, others are strongly associated with a particular habitat or microhabitat (Accordi and Hartz 2006, Gimenes and Anjos 2011, Alves et al 2012, Pinto et al 2013.…”