Habitats and landscapes associated with bird species in a lowland conifer-dominated ecosystem

Abstract

Human-induced effects on lowland conifer forests in hemiboreal regions are increasing because of expanded use of these northern ecosystems for raw materials, energy, and minerals as well as the potential effects of climatic changes. These forests support many breeding bird species across the Holarctic and allow the persistence of several boreal bird species in hemiboreal and even temperate regions. These bird species are of particular conservation concern as shifting patterns northward in forest composition caused by climate change will likely affect their populations. However, effective management and conservation options are limited because the specifics of these species' breeding habitats are not well understood. We modeled and mapped habitat suitability for 11 species of boreal birds that breed in the lowland conifer forests of the Agassiz Lowlands Ecological Subsection in northern Minnesota and are likely to have reduced breeding habitat in the future: Spruce Grouse (Falcipennis canadensis), Black-backed Woodpecker (Picoides arcticus), Olive-sided Flycatcher (Contopus cooperi), Yellow-bellied Flycatcher (Empidonax flaviventris), Boreal Chickadee (Poecile hudsonicus), Golden-crowned Kinglet (Regulus satrapa), Ruby-crowned Kinglet (Regulus calendula), Swainson's Thrush (Catharus ustulatus), Connecticut Warbler (Oporornis agilis), Palm Warbler (Setophaga palmarum), and Dark-eyed Junco (Junco hyemalis). Sets of 7 to 16 potential environmental covariates, including both stand-level and landscape attributes, were used to develop individual species models. Within this lowland conifer-dominated ecosystem, we found significant selection for specific forest and landscape characteristics by all but one of these species, with the best models including between one and nine variables. Habitat suitability maps were developed from these models and predictions tested with an independent dataset. Model performance depended on species, correctly predicting 56-96% of test data. We present a map combining suitability scores for five species of conservation concern that has been used for conservation planning and management opportunities across a broad, lowland forest landscape. We recommend managers utilize the detailed model development and validation framework to address local and regional conservation issues.

Keywords

• bird conservation
• boreal birds
• boreal forests
• forest management
• habitat suitability
• hemiboreal
• lowland coniferous forest
• MaxEnt