Estratanãgia de economia de energia ajuda os colibris a abastecer suas longas migrações
As descobertas ajudam a provar uma suspeita de longa data entre os cientistas que estudam os colibris. Eles também fornecem novos insights sobre as regras que os pa¡ssaros usam para determinar se devem conservar energia ou armazenar gordura.
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)
Um beija-flor de garganta rubi macho adulto em voo. Crédito: Brock e Sherri Fenton (CC BY 4.0)
Os colibris de garganta rubi usam a mesma estratanãgia de conservação de energia para sobreviver a jejuns noturnos e construir os depa³sitos de gordura de que precisam para alimentar longas migrações, mostra um estudo publicado na eLife .
As descobertas ajudam a provar uma suspeita de longa data entre os cientistas que estudam os colibris. Eles também fornecem novos insights sobre as regras que os pa¡ssaros usam para determinar se devem conservar energia ou armazenar gordura.
Minaºsculos colibris de garganta rubi comem constantemente nanãctar aa§ucarado para alimentar os movimentos rápidos das asas que os permitem pairar. Para conservar energia durante seus jejuns noturnos, os pa¡ssaros podem mudar para um modo de economia de energia chamado torpor , baixando a temperatura corporal e desacelerando seu metabolismo em até95%.
"Queraamos saber se os colibris usam esse mesmo mecanismo de economia de energia para construir mais rapidamente os depa³sitos de gordura que usara£o para alimentar suas migrações de 5.000 quila´metros entre seus criadouros na Amanãrica do Norte e as casas de inverno da Amanãrica Central", disse o primeiro autor Erich Eberts. , um Ph.D. estudante do Welch Lab, Universidade de Toronto Scarborough, Onta¡rio, Canada¡.
Para estudar como e quando os colibris implementam essa estratanãgia de economia de energia, Eberts e a equipe mediram asmudanças dia¡rias no corpo, na gordura e na massa magra de 16 colibris de garganta rubi durante três períodos: A estação de reprodução, final do vera£o, quando os pa¡ssaros se preparam para migrar, e durante o período tapico de migração das aves. Eles também mediram o consumo de oxigaªnio dos pa¡ssaros usando uma técnica chamada respirometria para determinar quando eles entraram em torpor.
Durante a anãpoca de reprodução , os colibris mantinham a massa corporal magra e são entravam em torpor quando seus estoques de gordura caaam abaixo de 5% de sua massa corporal. Essa "estratanãgia de emergaªncia energanãtica" costumava ser implantada nas noites em que iam dormir com reservas de energia mais baixas.
Mas no final do vera£o, quando os pa¡ssaros normalmente aumentam sua massa corporal em 20% para se sustentar durante a longa migração, eles param de usar o limite de 5% para entrar em torpor. Em vez disso, eles entram em torpor com mais frequência e em naveis mais elevados de gordura. Isso permite que eles conservem energia e acumulem gordura, mesmo a medida que as noites ficam cada vez mais longas. "Mostramos que os colibris abandonam a estratanãgia de emergaªncia energanãtica no final do vera£o e comea§am a usar o torpor para acumular o depa³sitos de gordura de que precisam para a migraçãoâ€, explica Eberts.
Os autores acrescentam que aprender mais sobre esta estratanãgia de economia de energia pode ser importante para a conservação de colibris de garganta rubi e outras espanãcies de aves migrata³rias que enfrentam o estresse crescente dasmudanças climáticas e perda de habitat.
"Nossas descobertas de que os colibris podem usar o torpor para lidar com diferentes desafios energanãticos ao longo do ciclo anual são importantes para compreender as diferenças em como esses e outros animais migrata³rios que não usam o torpor podem responder a futurasmudanças ambientais na disponibilidade de alimentos e na temperatura", conclui Kenneth Welch Jr., Professor Associado e Presidente Interino do Departamento de Ciências Biola³gicas da University of Toronto Scarborough, e coautor do estudo ao lado de Christopher Guglielmo, Professor da University of Western Ontario, Canada¡.