Banca de DEFESA: GUILHERME SANTOS TOLEDO DE LIMA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : GUILHERME SANTOS TOLEDO DE LIMA
DATA : 27/10/2017
HORA: 08:30
LOCAL: Sala de videoconferência da Rede Nacional de Ensino e Pesquisa, Centro de Convivência da UFRN
TÍTULO:

Birds of Caatinga – Individuals, populations and community-level persistence in a seasonally dry tropical forest during drought years

PALAVRAS-CHAVES:

 Birds, Caatinga, capture-recapture analysis, communities, drought, populations

 

PÁGINAS: 100
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

Global climate change is expected to increase the frequency and intensity of drought events in arid and semi-arid tropical regions. Although dry spells have been natural weather events in these regions, increases in your frequency may have cumulative effects on vertebrate populations and communities, exacerbating the severity of resource bottlenecks. Vertebrates with high mobility potential such as birds respond in different ways to drought events: diet and behavior changes to explore alternative resources, regional scale movements to track food, and adjust the territory sizes to local availability of resources. However, more severe and prolonged droughts can reduce recruitment and increase mortality rates in populations of sedentary and specialist birds. Current knowledge about the effects of drought on the avifauna of arid and semi-arid regions have been based on studies in Australia and Africa, while few studies have been conducted in the Neotropics. The objective of this thesis was to understand how a community and populations of insectivorous birds responded to a prolonged drought in Caatinga, between 2012 – 2015. Data were collected in Estação Ecológica do Seridó – RN, through systematic mist-netting in a seasonal frequency. Birds were captured in two grids of 12 ha with 48 sampling points each, established in two habitats: wood and shrubby caatinga. The captured birds were marked with aluminum bands and an individual color-combination of plastic bands. In the first chapter, we used capture-marking-recapture/resighting analysis to test the effects of habitat, precipitation, seasonality and of an unusually dry period on the monthly survival rates and population densities of four insectivorous passerines. Monthly survivals of Myiarchus tyrannulus, Hemitriccus margaritaceiventer and Polioptila plumbea fluctuated seasonally throughout the study, with the lowest values recorded in the dry intervals. Formicivora melanogaster survived constantly throughout the study. Annual survival rates of H. margaritaceiventer and F. melanogaster were markedly low in wood caatinga compared to shrubby caatinga. Densities of populations were higher in shrubby caatinga over almost all monitoring, and peak density in three of them occurred just after the rainy season of 2013, which followed the driest period of the study. In the second chapter, we used multiple-season occupancy models in a community approach to estimate the relative species richness in each sampling session, colonization, and local extinction rates during the intervals between sessions. Additionally, we tested for variations related to time, habitat, and functional groups. Relative species richness or the ratio of species at the study site to the number of species in the regional pool remained low throughout the study (20% – 51%), with higher estimates in shrubby compared to wood caatinga, ~ 42% vs. ~ 31%, respectively. Pollinators, seed dispersers and ecosystem engineers were characterized by colonization rates of less than 50%, and median to high extinction rates (40% – 60%), suggesting low fidelity to the study area. In contrast, granivorous and insectivorous species were resident in the community, with both low colonization and extinction probabilities (< 30%). Finally, in the third chapter we estimate territory sizes of Formicivora melanogaster during six resighting campaigns. We tested for the effects of habitat and relative air humidity (proxy of food availability) on territory sizes through an analysis of covariance. Between October 2014 and June 2016, we monitored six adult pairs and mapped 15 territories, whose estimates ranged from 0.52 to 3.94 ha. Territory sizes were inversely correlated with relative air humidity (F = 42.07; p < 0.01) and significantly higher in wood than shrubby caatinga (F = 14.53; p < 0.01), suggesting that adult pairs of F. melanogaster adjusted their territory sizes to the availability of resources in time and space.

MEMBROS DA BANCA:
Interno - 1678202 - CARLOS ROBERTO SORENSEN DUTRA DA FONSECA
Interno - 1718346 - EDUARDO MARTINS VENTICINQUE
Externo à Instituição - LUIZ AUGUSTO MACEDO MESTRE - UFPR
Presidente - 1439088 - MAURO PICHORIM
Externo à Instituição - RODRIGO LIMA MASSARA - UFMG