Passerine birds specialized in Giant Bulrush for nesting in subtropical salt marshes
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Data
2023-01-19
Autores
Pereira-Lima, Tamiris
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Universidade Estadual Paulista (Unesp)
Resumo
A reprodução e a nidificação das aves estão intrinsecamente relacionadas com as características ambientais do seu habitat. Ambientes com diversidade florística reduzida podem tornar aves especialistas em uma espécie vegetal particular para a sua nidificação. Hipotetizamos que, em brejos salinos subtropicais, ambientes com baixa diversidade vegetal, os passeriformes bate-bico (Phleocryptes melanops) e papa-piri (Tachuris rubrigastra) são especialistas e dependentes da Cyperaceae piri (Schoenoplectus californicus) como apoio para seus ninhos e como fonte de material nidular. Especificamente, objetivamos analisar os apoios dos ninhos e o material nidular das aves em um brejo salino subtropical, na Baía de Guaratuba, sudeste do Brasil, averiguando se há especialização ou não no uso do piri. Para tal, fizemos busca de ninhos de ambas as aves, em períodos entre 2011 e 2021, descrevemos suas medidas, os apoios de fixação e a composição do seu material nidular, bem como caracterizamos o ambiente local por meio de análises fitossociológicas. Analisamos se há uso especialista ou aleatório da vegetação contrapondo os dados de cobertura das espécies vegetais no ambiente com a sua respectiva utilização nos ninhos. Constatamos que o piri foi a planta mais utilizada tanto como apoio para fixação dos ninhos como para material nidular em ambas as espécies, apesar de não ser a planta mais abundante do ambiente. No geral, cerca de 60% dos ninhos de bate-bico (n = 160) e 80% dos ninhos do papa-piri (n = 102) estavam fixos em piri e que os ninhos diminuíram em altura ao longo dos anos (p < 0.01) para ambas as espécies). Notamos, entretanto, que embora o piri tenha ocorrido em baixas em proporções no ambiente (~10-20% da cobertura vegetal), foi encontrado em altas proporções no ninho (~70% do material nidular). Esses resultados indicam uma seleção especialista do piri pelas aves para a nidificação. Considerando que os brejos salinos são atualmente ameaçados pelas mudanças climáticas, o sucesso reprodutivo de ambas as espécies também poderá ser comprometido pela falta de ambiente para nidificação e/ou recurso nidular, ou até mesmo por tornar os ninhos mais suscetíveis a inundações. Portanto, nós sugerimos que a perpetuação das aves nestes ecossistemas pode estar em risco nas próximas décadas, alertando para a necessidade de estratégias de conservação.
Birds' reproduction and nesting are intrinsically related to the environmental features of their habitat. Environments with reduced floristic diversity can make birds specialists in a particular plant species for nesting. We hypothesized that in subtropical salt marshes, an environment with low plant richness, the passerines Wren-Like Rushbird (Phleocryptes melanops) and Many-Colored Rush Tyrant (Tachuris rubrigastra) are specialists and dependent on the Cyperaceae Giant Bulrush (Schoenoplectus californicus) for nesting. Specifically, we aimed to analyze the nesting support and the nesting material of these birds in a subtropical salt marsh, located in Guaratuba Bay, southern Brazil, to investigate a possible specialization in the use of Giant Bulrush. Thereunto, for both bird species, in periods between 2011 and 2021, we made nests measurements, described their nesting supports and nesting material, as well as we characterized the local environment using phytosociological analyzes. We analyzed if there is a specialization in the use of vegetation, comparing the coverage data of plant species with their respective use in nests. We found that Giant Bulrush was the most used plant both as support and as nesting material, despite not being the most abundant plant in the environment. In general, about 60% of Wren-Like Rushbird (n = 160) and 80% of Many-Colored Rush Tyrant (n = 102) nests found were fixed in Giant Bulrush, and we noticed that the nests decreased in height over the years (p < 0.01 for both species). We also noticed that, although the Giant Bulrush occurred in low proportions in the local environment (10-20% of vegetation cover), it was found in high proportions in nests (~70% of the nesting material). These results indicate a specialist selection of the Giant Bulrush by the birds for nesting. Considering that the salt marshes is currently threatened by climatic changes, the reproductive success of both species can also be compromised by the lack of a nesting environment and/or nesting resource, or even being more susceptible to flooding (i. e.). Therefore, we suggest that the bird’s perpetuation in these ecosystems may be at risk in the future decades, warning to the need for conservation strategies.
Birds' reproduction and nesting are intrinsically related to the environmental features of their habitat. Environments with reduced floristic diversity can make birds specialists in a particular plant species for nesting. We hypothesized that in subtropical salt marshes, an environment with low plant richness, the passerines Wren-Like Rushbird (Phleocryptes melanops) and Many-Colored Rush Tyrant (Tachuris rubrigastra) are specialists and dependent on the Cyperaceae Giant Bulrush (Schoenoplectus californicus) for nesting. Specifically, we aimed to analyze the nesting support and the nesting material of these birds in a subtropical salt marsh, located in Guaratuba Bay, southern Brazil, to investigate a possible specialization in the use of Giant Bulrush. Thereunto, for both bird species, in periods between 2011 and 2021, we made nests measurements, described their nesting supports and nesting material, as well as we characterized the local environment using phytosociological analyzes. We analyzed if there is a specialization in the use of vegetation, comparing the coverage data of plant species with their respective use in nests. We found that Giant Bulrush was the most used plant both as support and as nesting material, despite not being the most abundant plant in the environment. In general, about 60% of Wren-Like Rushbird (n = 160) and 80% of Many-Colored Rush Tyrant (n = 102) nests found were fixed in Giant Bulrush, and we noticed that the nests decreased in height over the years (p < 0.01 for both species). We also noticed that, although the Giant Bulrush occurred in low proportions in the local environment (10-20% of vegetation cover), it was found in high proportions in nests (~70% of the nesting material). These results indicate a specialist selection of the Giant Bulrush by the birds for nesting. Considering that the salt marshes is currently threatened by climatic changes, the reproductive success of both species can also be compromised by the lack of a nesting environment and/or nesting resource, or even being more susceptible to flooding (i. e.). Therefore, we suggest that the bird’s perpetuation in these ecosystems may be at risk in the future decades, warning to the need for conservation strategies.
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Palavras-chave
Aves, Pássaros, Ecologia, Ninhos, Charcos e brejos, Nesting material, Nesting support, Specialist bird, Many-Colored Rush Tyrant, Wren-Like Rushbird