Divisão parental do cuidado à prole no sabiá-barranco (Turdus leucomelas)
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Data
2020-10-21
Autores
Haddad, Renan Nasser Medeiros [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Aves tropicais apresentam estratégias reprodutivas particulares em comparação às espécies da região temperada do hemisfério norte, como a menor prole, maior investimento em cada filhote, estágio de ninhego mais curto e estágio pós-ninho extenso. No entanto, estudos sobre o cuidado parental entre as aves da região tropical são escassos em relação às aves do hemisfério norte temperado especialmente quando se considera a diversidade de aves tropicais. Portanto, são necessários mais estudos para compreender as diferenças, diversidade das espécies e padrões comportamentais da região. Nesta dissertação descrevemos a divisão do cuidado parental entre os sexos do sabiá-barranco (Turdus leucomelas), espécie de passeriforme socialmente monogâmico e monomórfico. Abordamos os dois estágios do ciclo reprodutivo das aves altriciais que são considerados os mais custosos em relação ao gasto energético parental, o estágio de ninhego e o estágio pós-ninho, isto é, após os filhotes terem deixado o ninho. O estudo foi feito no campus da Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP) em Rio Claro, São Paulo. Usando câmeras instaladas junto aos ninhos, obtivemos 153,5 h de gravações do estágio de ninhego em 33 ninhos e 24 casais diferentes entre 2015 e 2017. Com observações diretas, fizemos 84,8 h de observação efetiva do estágio de pós-ninho em oito famílias e 13 filhotes diferentes em 2018. No estágio de ninhego ambos os sexos forneceram alimento e realizaram limpeza do ninho. No entanto, machos alimentaram os filhotes de proles grandes mais frequentemente do que fêmeas. Apenas fêmeas realizaram a termorregulação dos filhotes, e o tempo desta atividade diminuiu com a idade dos filhotes. Não houve diferença na limpeza do ninho entre os sexos. No estágio pós-ninho, não houve diferença no fornecimento de alimento aos filhotes entre os sexos, que também não variou com o tamanho da ninhada e sua idade. A taxa de fornecimento de alimento também não alterou a frequência dos comportamentos de solicitação de alimento ou de forrageio pelos filhotes, mas este último se tornou mais frequente ao longo do desenvolvimento. Observamos a divisão do cuidado parental no cuidado à prole, segundo quatro padrões: divisão da prole, cuidado único do macho, cuidado único da fêmea, e cuidado biparental de proles de um único filhote. Filhotes que receberam fornecimento de alimento biparental foram mais frequentemente alimentados, do que aqueles que receberam uniparental. Portanto, o investimento parental é distinto entre o macho e a fêmea durante o cuidado dos ninhegos, especialmente em proles maiores, no entanto, durante o cuidado pósninho a provisão de alimento é similar entre os sexos, e a diferença é existe na divisão da prole, e em quantos filhotes cada indivíduo do casal cuida durante este período.
Tropical birds have particular reproductive strategies in comparison to north temperate species, such as smaller clutch size, higher investment per individual chick, shorter nesting stages and extended post-fledging stages. However, studies regarding parental care of birds in the tropical region are scarce in comparison to the temperate northern hemisphere, especially when you consider the bird diversity of the tropics. Therefore, more studies are necessary to a better understanding of the differences, unique diversity, and behavioural patterns of the region. In this dissertation we describe the division of parental care between the sexes of the Pale-breasted Thrush (Turdus leucomelas), a socially monogamous and monomorphic passerine. We studied the two stages considered more energetically expensive for altricial birds, the nesting and post-fledging stages. The study was conducted in the campus of the Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP) located in Rio Claro, São Paulo. Using cameras positioned close to the nests, we recorded 153.5 h of the nesting stage care from 33 nests and 24 different reproductive pairs between 2015 and 2017. With direct observations, we carried out 84.8 h of effective observation of post-fledging care in eight families and 13 different fledglings in 2018. In the nesting stage, both sexes provisioned food for the nestlings and performed nest sanitation. However, males fed more frequently larger broods than females did. Only females brooded nestlings and the time spent on this activity reduced as the brood aged. There was no difference in nest sanitation between sexes. In the post-fledging stage, there was no difference in food provisioning rates between sexes, neither brood age nor brood size affected rates of food provisioning. Food provisioning rates did not affect frequency of fledgling behaviour of foraging and fledgling vocalization, but foraging became more frequent as fledglings aged. There was brood division in parental care of the brood, of which there was four patterns: brood division, male-only care, female-only care, and biparental care of broods with a single fledgling. Fledglings that received biparental food provisioning were more frequently fed than those that received uniparental feeding. Therefore, parental investment was similar between males and females during the nestling stage, especially in larger broods, however, during the post-fledging stage there is no apparent difference between food provisioning between sexes, only differing in regards to brood division, and how many fledglings each parent cares for.
Tropical birds have particular reproductive strategies in comparison to north temperate species, such as smaller clutch size, higher investment per individual chick, shorter nesting stages and extended post-fledging stages. However, studies regarding parental care of birds in the tropical region are scarce in comparison to the temperate northern hemisphere, especially when you consider the bird diversity of the tropics. Therefore, more studies are necessary to a better understanding of the differences, unique diversity, and behavioural patterns of the region. In this dissertation we describe the division of parental care between the sexes of the Pale-breasted Thrush (Turdus leucomelas), a socially monogamous and monomorphic passerine. We studied the two stages considered more energetically expensive for altricial birds, the nesting and post-fledging stages. The study was conducted in the campus of the Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP) located in Rio Claro, São Paulo. Using cameras positioned close to the nests, we recorded 153.5 h of the nesting stage care from 33 nests and 24 different reproductive pairs between 2015 and 2017. With direct observations, we carried out 84.8 h of effective observation of post-fledging care in eight families and 13 different fledglings in 2018. In the nesting stage, both sexes provisioned food for the nestlings and performed nest sanitation. However, males fed more frequently larger broods than females did. Only females brooded nestlings and the time spent on this activity reduced as the brood aged. There was no difference in nest sanitation between sexes. In the post-fledging stage, there was no difference in food provisioning rates between sexes, neither brood age nor brood size affected rates of food provisioning. Food provisioning rates did not affect frequency of fledgling behaviour of foraging and fledgling vocalization, but foraging became more frequent as fledglings aged. There was brood division in parental care of the brood, of which there was four patterns: brood division, male-only care, female-only care, and biparental care of broods with a single fledgling. Fledglings that received biparental food provisioning were more frequently fed than those that received uniparental feeding. Therefore, parental investment was similar between males and females during the nestling stage, especially in larger broods, however, during the post-fledging stage there is no apparent difference between food provisioning between sexes, only differing in regards to brood division, and how many fledglings each parent cares for.
Descrição
Palavras-chave
Cuidado parental, Parental care, Fornecimento de alimento, Food provisioning, Limpeza de ninho, Nest sanitation, Conflito sexual, Sexual conflict, Estágio de ninhego, Nestling stage, Estágio pós-ninho, Post-fledging stage, Filhote, Fledgling, Sabiá-barranco, Pale-breasted thrush, Turdus leucomelas