Banca de DEFESA: PHOEVE MACARIO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : PHOEVE MACARIO
DATA : 28/06/2019
HORA: 08:30
LOCAL: Sala de videoconferência do centro de convivência
TÍTULO:

Population and reproductive parameters of granivorous birds in the Caatinga: life strategies in a seasonally dry tropical environment


PALAVRAS-CHAVES:

Ammodramus humeralis, apparent survival, Columbina picui, Columbina minuta, MARK program, nest predation, nomadism.


PÁGINAS: 133
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

The establishment of patterns that explain latitudinal variations in avian life history is based on data from tropical rainforests, and there are gaps regarding the evolution of their traits in seasonal tropical environments. The strong seasonality of these environments is related to the rainfall regime, with wet and dry seasons well-marked. In addition, they have atypical climatic variation, exhibiting cycles with prolonged dry periods. As consequence, they limit the availability of food, shelter and nesting sites, altering the dynamics of bird populations. The effects of these periods reflect what is to come in a scenario of global climate change, where is foreseen the increase of shorter rainy seasons. Thus, it is important to understand the strategies of bird populations to keep up with seasonality, and how they respond to severely dry periods, especially granivorous, which are among the most abundant species in such environments. The Caatinga is an example of a tropical seasonally dry ecosystem. This domain presents a variable and stressful rainfall regime, where in many regions annual rainfall does not exceed 500 mm. Therefore, the aim of this thesis was to estimate population and reproductive parameters of granivorous birds in a Caatinga area, during and after a severely dry period. We developed the study at the Estação Ecológica do Seridó, city of Serra Negra do Norte, RN, Brazil. The thesis is structured in three chapters. In Chapter 1, we estimated detection and survival rates of the passerine Ammodramus humeralis. We tested the hypotheses that apparent survival would be lower than that described for tropical rainforests, influenced by seasonality and negatively affected by the prolonged dry period. To analyze the data, we used Huggins' robust design model in the MARK program. Contrasting our hypotheses, the best fit model considered apparent survival as constant, and the annual estimates among those observed in rain forests. We believe that the population studied here was able to maintain a constant survival, even in the face of a period where resources were severely scarce, because they did not reproduce. Since reproduction involves an energy cost, not reproducing compensates the waste that reduces survival rates. In chapter 2, we describe reproductive characteristics (egg size and weight, incubation and nestling period, nest density and behavioral traits) of Columbina minuta and Columbina picui. We also estimated nest daily survival rates (TSD) investigating whether the height, plant support, camouflage, stage (egg or nestling) and nest age influence this parameter. From it, we obtained rates of reproductive success and predation. We evaluated the hypothesis that TSD would be affected by environmental characteristics, higher during the nestling stage, and that predation would be lower than other orders species. We used the Mayfield method and developed nest survival models in the MARK program for data analysis. We verified that both species nest in several plant species at heights between 0 and 400 cm, and that only camouflage was an important factor in TSD. The estimates were higher during the nestling phase, corroborating our hypothesis. Predation was the main cause of losses, however with rates similar to those observed for species of other orders and other environments. Our results contribute to a better understanding of the evolution of life history of birds inhabiting tropical regions, since the existing pattern is based on data from rain forests. In chapter 3, we estimated detection rates and abundance of C. minuta and C. picui in two different physiognomies. We evaluated the hypothesis that the density is higher in the open physiognomy, that the species are more abundant during the wet season, and that they are able to perform regional movements. For analyzes, we developed Huggins’ closed population models in MARK program. The results corroborate our three hypotheses. The population size suggested greater abundance in savanna shrub and during the wet season. Recoveries of C. minuta in other Caatinga localities, combined with low capture and recapture rates, and low fidelity to the sample areas, indicate that nomadism can be the main strategy adopted by this species to maintain its populations in face of the climatic unpredictability of the Caatinga. The present thesis presents unprecedented results regarding the natural history of birds inhabiting tropical seasonally dry environments. In addition, it contributes to the understanding of the strategies adopted by granivorous species to maintain their populations in periods of severe resource scarcity, which will be much more frequent in a climate change scenario.


MEMBROS DA BANCA:
Presidente - 1439088 - MAURO PICHORIM
Interna - 3058386 - VANESSA GRAZIELE STAGGEMEIER
Externa à Instituição - ANA MARIA DE OLIVEIRA PASCHOAL
Externa à Instituição - ANGELICA MARIA KAZUE UEJIMA - UFPE
Externa à Instituição - Luciana Vieira de Paiva - UFERSA
Notícia cadastrada em: 11/06/2019 08:50
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