Estudo etológico do casuar (Casuarius casuarius) durante a época reprodutiva no Parque Ornitológico de Lourosa
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2016-10-04
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Recentemente tem-se assistido ao fenómeno da globalização que, apesar de ser uma
mais-valia para o Homem, evidenciou-se devastadora para algumas espécies de animais,
de entre as quais se destaca o Casuar. Este, sofreu um acentuado declínio populacional
provocado por inúmeros fatores de entre os quais nos parecem ser de salientar a
fragmentação do habitat (p.ex., construção de estradas que causaram uma enorme
incidência de mortes por atropelamento), ataques por parte de cães e a degradação do
habitat (principalmente pelos incêndios). O acentuado declínio destes animais incitou a
criação de programas que visassem a sua reprodução em cativeiro, tendo-se esta
mostrado muito difícil devido ao desconhecimento de muitos pormenores relativos à
biologia da espécie. Deste modo, o presente trabalho tem como principal objetivo o
estudo de aspetos do ciclo de vida do casuar, concretamente o seu processo reprodutivo.
Para a execução do trabalho prático foram utilizados 3 espécimes de casuares
(Casuarius casuarius), existentes no Parque ornitológico de Lourosa, cujo
comportamento reprodutivo foi objeto de descrição. Os trabalhos compreenderam 4
fases. Numa primeira fase foi aperfeiçoado o etograma, tendo sido acrescentados
comportamentos complementares aos inicialmente previstos. Numa segunda fase, os
animais foram observados separadamente, a fim de descrever os comportamentos
manifestados fora da época reprodutiva, bem como para identificar os comportamentos
que influenciam a escolha de um parceiro por parte da fêmea. Finalmente, numa terceira
e quarta fases, foi feito o registo dos comportamentos reprodutivos dos casais 1 (C1) e 2 (C2), respetivamente.
A observação sistemática das aves e a análise dos resultados obtidos, permitiu chegar a
algumas conclusões sobre os hábitos manifestados por estes animais. Com a
aproximação da época reprodutiva, os animais mostraram-se mais agitados e
vocalizaram mais, principalmente durante o início da corte à fêmea. Nesse período, esta
mostrou-se mais recetiva ao macho_1, formando com este o C1. Alguns dos
comportamentos manifestados durante a época reprodutiva pelos diferentes casais (C1 e
C2) podem ter sido determinantes para a postura de ovos fecundados, já que daí
resultaram 6 ovos (3 de cada casal). Destes apenas 5 foram incubados, não tendo
eclodido nenhum e estando apenas os ovos de C2 fecundados e com desenvolvimento
fetal. Assim sendo, o próprio ato copulatório pode ser considerado um fator de insucesso,
já que, o macho_1 mostrou sérios problemas para executar este comportamento,
comparativamente ao macho_2. Tendo o número de cópulas efetuadas pelo macho_2
sido até superior. A morte embrionária atrás referida pode ter acontecido devido a fatores
ambientais, uma vez que o final do período de incubação coincidiu com um período em
que as condições ambientais apresentam picos de temperatura e muito baixa humidade relativa.
Recently we have witnessed the globalization phenomenon, which revealed to be devastating for some species of animals, among which is the Cassowary. This species suffered a sharp population decline caused by many factors among which we may highlight the habitat fragmentation (e.g., road construction that caused a huge incidence of deaths by trampling), dog attacks, and habitat degradation (mainly by fire). Thus, this paper aims to study aspects of the cassowary lifecycle, specifically its reproductive process. For the implementations of the practical work, 3 specimens of the Cassowary (Casuarius casuarius), belonging to the avian collection of the Lourosa Ornithological Park were used, in order to describe it’s reproductive behaviour. The work was comprised of four phases. Initially, the work aimed at perfecting the ethogram, with the addition of complementary behaviours. Subsequently, the animals were observed separately in order to describe the manifested behaviours outside the breeding season as well as to identify the behaviours that encourage the choice of a partner by the female. Finally, in the third and fourth phases, the reproductive behaviours of married couples were recorded, firstly for couple 1, and later for couple 2, respectively. The systematic observation of the birds, and the analysis of the results allowed to draw some conclusions about the habits manifested by these animals. With the approach of reproductive age, the animals were more agitated and vocalized more, especially during the early courtship to the female. During this period, the female was more receptive to the male number 1, forming with the couple 1 (C1). Some of the behaviours manifested during the breeding season for the different couples (C1 and C2) may have been decisive for laying fertilized eggs, since it resulted in 6 eggs (3 of each couple). Of these, only 5 were incubated but any hatched. Only the eggs of C2 were fertilized and showed foetal development. Also, the copulatory act can be considered a failure factor, since the male 1 showed serious problems to perform this behaviour, compared to male_2. Also, the number of copulations performed by male_2 was superior. The embryonic death mentioned above may be due to environmental factors, since the end of the incubation period, and coincided with a period when there were high temperature and very low relative humidity environmental peaks.
Recently we have witnessed the globalization phenomenon, which revealed to be devastating for some species of animals, among which is the Cassowary. This species suffered a sharp population decline caused by many factors among which we may highlight the habitat fragmentation (e.g., road construction that caused a huge incidence of deaths by trampling), dog attacks, and habitat degradation (mainly by fire). Thus, this paper aims to study aspects of the cassowary lifecycle, specifically its reproductive process. For the implementations of the practical work, 3 specimens of the Cassowary (Casuarius casuarius), belonging to the avian collection of the Lourosa Ornithological Park were used, in order to describe it’s reproductive behaviour. The work was comprised of four phases. Initially, the work aimed at perfecting the ethogram, with the addition of complementary behaviours. Subsequently, the animals were observed separately in order to describe the manifested behaviours outside the breeding season as well as to identify the behaviours that encourage the choice of a partner by the female. Finally, in the third and fourth phases, the reproductive behaviours of married couples were recorded, firstly for couple 1, and later for couple 2, respectively. The systematic observation of the birds, and the analysis of the results allowed to draw some conclusions about the habits manifested by these animals. With the approach of reproductive age, the animals were more agitated and vocalized more, especially during the early courtship to the female. During this period, the female was more receptive to the male number 1, forming with the couple 1 (C1). Some of the behaviours manifested during the breeding season for the different couples (C1 and C2) may have been decisive for laying fertilized eggs, since it resulted in 6 eggs (3 of each couple). Of these, only 5 were incubated but any hatched. Only the eggs of C2 were fertilized and showed foetal development. Also, the copulatory act can be considered a failure factor, since the male 1 showed serious problems to perform this behaviour, compared to male_2. Also, the number of copulations performed by male_2 was superior. The embryonic death mentioned above may be due to environmental factors, since the end of the incubation period, and coincided with a period when there were high temperature and very low relative humidity environmental peaks.
Descrição
Dissertação de Mestrado em Engenharia Zootécnica
Palavras-chave
Comportamento animal , Casuariiformes , Reprodução , Incubação do ovo