EAGER: Utilizing arthropod prey species' phenology, availability, and life history at the deciduous-boreal ecotone to assess bird range geographic shifts

University Of Maine, Orono ME

Investigators

Abstract

While there is much evidence that plants and animals are changing where they live in response to shifts in climate, it remains unclear how they do so and whether changes in one species affect those in other species. Birds, for example, can move easily from one region to another, but the plants and insects they depend on for food cannot. This project explores the possibility that birds may find suitable climatic conditions in a new area but be deterred from moving there because the plants and insects they typically feed on have not been able to move there. Researchers in Maine will use DNA to measure the diets of birds in a broad area where one type of forest stops and another type begins. They will test two possible explanations for why some birds are expanding into one of the forest types where they did not occur previously, while others species appear stuck in one place and are experiencing declines. The first explanation is that the type of food used by the birds is more available for the expanding species than for the declining species. The second explanation is that there is a mismatch in timing between the when food becomes available and when the declining species start to breed. Researchers will engage undergraduate students, citizen scientists, and public school children in the project; everyone will work together to collect data and to discover the links between birds, their food, and climate. The insects and spiders consumed by birds within the boreal-deciduous ecotone will be identified using metabarcoding of 16S mitochondrial and cytochrome oxidase I genes. Three groups of insectivorous forest birds will be sampled: "leading edge" species (those that are expanding from a southern/deciduous range), "trailing edge" species (those that are declining and typically occur in boreal forest), and habitat generalists (those that occur more broadly across the region or habitat types). Food availability and use will be assessed relative to both time (phenology) and place (habitat). Life history, range, and behavioral characteristics of prey items will be used to compare the diets of the three bird groups. Measures of food use will also be compared to timing of breeding and regional long-term population trends from the Breeding Bird Survey to examine possible effects of food availability and use on demography.