Sound attenuation in forest and roadside environments: Implications for avian point-count surveys

Animal science

Climate-sensitive forecasts of marked short-term and long-term changes in the distributions or abundances of Northwestern boreal landbirds

Climate change presents a major threat to biodiversity globally. Northern ecosystems, such as Canada's boreal forest, are predicted to experience particularly severe climate-induced changes. These changes may reduce the carrying capacity and habitat suitability of the boreal forest for many wildlife species. Boreal birds are susceptible to both direct and indirect effects of climate change, and several studies have predicted northward shifts in species distributions as temperatures become warmer. We forecasted spatially-explicit changes in the densities of 72 boreal landbird species using integrated climate change projections and a forest dynamics model in the Taiga Plains ecozone of the Northwest Territories (NT), Canada, over the 2011–2091 horizon. We 1) identified ''winner,'' ''loser,'' and ''bellringer'' species over short (2031) and long-term (2091) forecasts, 2) mapped landbird range and density changes under three contrasting Global Circulation Models (GCMs), and 3) quantify differences in landbird density predictions across a latitudinal gradient. Species that showed a moderate increase or decrease in their predicted abundance were considered ''winners'' and ''losers,'' respectively. Species that showed a marked increase or decrease – a doubling or halving – of their predicted abundance in all three GCMs, were termed ''bellringers''. From 2011–2031, only 2/72 (2.8%) were considered winners, and 3/72 (4.2%) were losers. From 2011–2091, the abundance of more species was predicted to change: 26/72 (36.1%) were winners, and 10/72 species (13.9%) were losers. Four species were considered bellringers: Gray-cheeked Thrush, White-crowned Sparrow, Fox Sparrow, and American Tree Sparrow. Overall, projected range shifts were strongly oriented along a southeast-to-northwest axis. Shifts to the north and south were evenly distributed among all three GCMs. Our results suggest that future climate-mitigated distribution shifts and population declines of boreal landbirds will require targeted conservation actions. They also highlight the importance of the NT as a potential refugium for many boreal-breeding landbird species in Canada

Predação de ninhos artificiais em uma ilha na Mata Atlântica: testando o local e o tipo de ovo Artificial nest predation in Atlantic Forest Island: testing the place and the different types of egg

Experimentos com ninhos artificiais são utilizados para testar hipóteses ecológicas e comportamentais que influenciam na predação de ninhos naturais. O tamanho do ovo, a textura da casca e a cor podem influenciar na taxa de predação, porém poucos estudos avaliam qual modelo de ovo é o mais adequado para simular a predação de ninhos em áreas tropicais. O objetivo deste trabalho foi comparar a predação de diferentes modelos de ovos (ovos de codorna, massa de modelar e canários) no solo e a 1,30 m de altura no sub-bosque. O experimento foi realizado Ilha Anchieta, Ubatuba, São Paulo, Brasil. Foi encontrada uma diferença significativa na taxa de predação entre os ovos de codorna (71,87%) e sintéticos (93,75%) e entre os ovos de codorna e de canário (100%) no solo. Entretanto, não houve diferença significativa entre os ovos sintéticos e de canário. Os ninhos no sub-bosque apresentaram um padrão diferenciado do solo quando se refere aos ovos de codorna (25%) e sintéticos (28,1%), mas houve diferenças significativas quando os ovos de canário foram comparados com os ovos sintéticos e de codorna. Nosso trabalho demonstrou que diferentes tipos de ovos sobre uma mesma pressão de mesopredadores apresentaram taxas de predação diferentes. Portanto, estudos que avaliam o sucesso reprodutivo da avifauna baseado na predação de ninhos artificiais devem considerar a utilização de diferentes tipos de ovos e estratos na vegetação.<br>Experiments on artificial nests are usually used to test ecological hypothesis and behavioural that affects the predation of natural bird nests. It is has been discussed about the size of the egg, texture and color affecting predation rate, but a few studies evaluate which egg type is more appropriate to simulate nest predation in tropical areas. The objective of this work was to compare the predation of different models of eggs (Coturnix coturnix, plasticine and Serinus canarius) on the ground and understory in a island with high abundance of nest predators. The study was carry out in October 2004 at Anchieta Island, Ubatuba, São Paulo, Brazil. The nests on the ground showed a statistical significance difference in the predation of quail eggs, plasticine and canary eggs. However, we did not find differences between plasticine and canaries eggs. The nests in the understory had a different pattern on the ground of quail eggs (25%) and plasticine (28%) and there was a difference when we compare canary eggs with plasticine and quail eggs. Our work pointed out that different eggs may have different predation rates. Therefore, studies that evaluate reproductive fitness of the bird community based on artificial nests must considered different egg types and strata