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1. A bird’s eye view of ecosystem conversion: Examining the resilience of piñon-juniper woodlands and their avian communities in the face of fire regime change

   https://doi.org/10.1016/j.foreco.2023.121368  

   Woolet, Jamie; Stevens-Rumann, Camille S; Coop, Jonathan D; Pejchar, Liba (August 2023, Forest Ecology and Management)

   Climate change and land-use legacies have caused a shift in wildfires and post-fire growing conditions. These changes have strong potential to diminish the resilience of many ecosystems, with cascading effects and feedbacks across taxa. Piñon-juniper (PJ) woodlands are a diverse and widespread forest type in the western US and are home to many obligate and semi-obligate bird species. As such, this system is ideal for understanding wildfire resilience, or lack thereof, in terms of both vegetation and wildlife associations. This study evaluated post-fire vegetation structure and associated avian communities following three wildfires; one that burned one year prior to sampling (recent fire), and two that burned approximately 25 years previously (old fires). Vegetation characteristics and the habitat use of PJ-associated bird species were compared across severely burned patches, unburned refugia, and unburned sites outside of the burn perimeter. We expected wildfire to alter vegetation and bird usage for the first few years post-fire, which we observed in our recent burns. However, even 25-years post-fire, little recovery to PJ woodland had occurred and the associated bird communities had not returned, compared to unburned areas. No piñon regeneration was observed in any burned areas and no juniper regeneration in the recent fire. Piñon seedling densities in unburned sites and refugia averaged 80 ha−1 and 151 ha−1, respectively, while juniper seedling densities were 220 ha−1 in both habitat types. Habitat use for thirteen PJ-associated species were modeled, three of which (Woodhouse’s Scrub Jay, Ash-throated Flycatcher, and Virginia’s Warbler) used all habitats. Four species (American Robin, Gray Vireo, Black-throated Gray Warbler, and Gray Flycatcher) were essentially absent from the old burn habitat, reflecting species-specific need for mature piñon or juniper trees and/or greater canopy cover. Conversely, birds that were present in the old burn habitat (including Virginia’s Warbler, Blue-gray Gnatcatcher, Woodhouse’s Scrub-jay, Ash-throated Flycatcher, and Spotted Towhee) are typically associated with habitat edges, high shrub cover, or cavity nests. Altered vegetation structure and bird habitat use in burned areas 25 years post-fire are evidence for enduring conversion to non-forest vegetation types. However, unburned refugia embedded in burned areas maintain forest attributes and support obligate bird communities, supporting ecological function and biological diversity. 

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2. Effects of Prairie Degradation and Restoration on Box Turtle Thermal Ecology

   Yerdon, Gabriel L; Royal, Ethan J; Kross, Chelsea S; Willson, John D (March 2023, Journal of herpetology)

   Prairie habitat loss in the United States has led to population declines in many prairie-associated species, including Ornate Box Turtles (Terrapene ornata). Northwest Arkansas is an intergrade zone between the prairie-dwelling T. ornata and the more forestassociated Three-Toed Box Turtle (Terrapene carolina). As such, limited information exists on the potential differences in physiology and thermal ecology between the two box turtle species and how those differences might influence their habitat use. We addressed gaps in our knowledge of the thermal and spatial ecology of T. ornata and T. carolina with a three-part study. First, we compared the thermal profiles of refugia, open, and vegetated microhabitats across degraded prairie, restored prairie, and adjacent forest macrohabitats using operative temperature models and a linear mixed effect model. Second, we measured total evaporative water loss of both species across a range of body sizes. Finally, we fitted a subset of turtles with iButton data loggers and monitored them in the field to examine carapace temperatures and habitat use. Operative temperature models recorded high, largely homogeneous temperatures across microhabitats in degraded prairie and heterogeneous temperatures across restored prairie microhabitats, while forest habitat maintained stable, cool temperatures. Both species exhibited similar evaporative water loss rates; however, T. ornata experienced a broader range of temperatures in the field. Terrapene ornata were exclusively found in prairie habitat, whereas T. carolina was often found in forested habitats and subsurface refugia. Our results demonstrate key differences in box turtle thermal biology and highlight suboptimal thermal characteristics in degraded prairie and forest habitat that should be considered in prairie restoration and management for T. ornata conservation. 

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3. Amazonian birds in more dynamic habitats have less population genetic structure and higher gene flow

   https://doi.org/10.1111/mec.16886  

   Johnson, Oscar; Ribas, Camila C.; Aleixo, Alexandre; Naka, Luciano N.; Harvey, Michael G.; Brumfield, Robb T. (March 2023, Molecular Ecology)

   Abstract Understanding the factors that govern variation in genetic structure across species is key to the study of speciation and population genetics. Genetic structure has been linked to several aspects of life history, such as foraging strategy, habitat association, migration distance, and dispersal ability, all of which might influence dispersal and gene flow. Comparative studies of population genetic data from species with differing life histories provide opportunities to tease apart the role of dispersal in shaping gene flow and population genetic structure. Here, we examine population genetic data from sets of bird species specialized on a series of Amazonian habitat types hypothesized to filter for species with dramatically different dispersal abilities: stable upland forest, dynamic floodplain forest, and highly dynamic riverine islands. Using genome‐wide markers, we show that habitat type has a significant effect on population genetic structure, with species in upland forest, floodplain forest, and riverine islands exhibiting progressively lower levels of structure. Although morphological traits used as proxies for individual‐level dispersal ability did not explain this pattern, population genetic measures of gene flow are elevated in species from more dynamic riverine habitats. Our results suggest that the habitat in which a species occurs drives the degree of population genetic structuring via its impact on long‐term fluctuations in levels of gene flow, with species in highly dynamic habitats having particularly elevated gene flow. These differences in genetic variation across taxa specialized in distinct habitats may lead to disparate responses to environmental change or habitat‐specific diversification dynamics over evolutionary time scales. 

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4. Meta-analysis shows that overabundant deer (Cervidae) populations consistently decrease average population abundance and species richness of forest birds

   https://doi.org/10.1093/ornithapp/duab040  

   Crystal-Ornelas, Robert; Brown, Jeffrey A; Valentin, Rafael E; Beardsley, Caroline; Lockwood, Julie L (September 2021, Ornithological Applications)

   Abstract Local-scale studies have shown that an overabundance of Cervidae species (deer, elk, moose) impacts forest bird communities. Through meta-analysis, we provide a generalized estimate of the overall direction and magnitude of the indirect effects overabundant cervids have on avian species. We conducted 2 distinct meta-analyses that synthesized data on 130 bird species collected from 17 publications. These analyses compared bird species’ population abundance and/or species richness at sites with overabundant cervids to sites with lower cervid abundance or without cervids. We evaluated whether the impacts of overabundant cervids are generally in the same direction (positive, negative) across avian species and locations and if effects vary in magnitude according to avian nesting location and foraging habitat. We found that where cervids were overabundant, there was a significant decrease in mean bird population abundance and species richness. Species that nest in trees, shrubs, and on the ground showed the largest decreases in abundance, as did species whose primary habitat is forest and open woodland and species that are primarily insectivores or omnivores. We did not find significant decreases in abundance for avian species that nest in cavities, whose primary habitat is grassland or scrub, nor for species that mainly eat seeds. Our results indicate that overabundant cervids, likely through their direct effects on vegetation and indirect effects on insects and forest birds, negatively impact individual bird populations and decrease overall avian species richness. 

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5. Climate-Related Distribution Shifts of Migratory Songbirds and Sciurids in the White Mountain National Forest

   https://doi.org/10.3390/f10020084  

   Tatenhove, Aimee Van; Filiberti, Emily; Sillett, T. Scott; Rodenhouse, Nicholas; Hallworth, Michael (February 2019, Forests)

   Climate change has been linked to distribution shifts and population declines of numerous animal and plant species, particularly in montane ecosystems. The majority of studies suggest both that low-elevation avian and small mammal species are shifting up in elevation and that high-elevation avian communities are either shifting further upslope or relocating completely with an increase in average local temperatures. However, recent research suggests numerous high elevation montane species are either not shifting or are shifting down in elevation despite the local increasing temperature trends, perhaps as a result of the increased precipitation at high elevations. In this study, we examine common vertebrate species distributions across the Hubbard Brook valley in the White Mountain National Forest, including resident and migratory songbirds and small mammals, in relation to historic spring temperature and precipitation. We found no directional change in distributions through time for any of the species. However, we show that the majority of low-elevation bird species in our study area respond to warm spring temperatures by shifting upslope. All bird species that shifted were long-distance migrants. Each low-elevation migrant species responded differently to warm spring temperatures, through upslope distribution expansion, downslope distribution contraction, or total distribution shift upslope. In contrast, we found a majority of high-elevation bird species and both high- and low-elevation mammal species did not shift in response to spring temperature or precipitation and may be subject to more complex climate trends. The heterogeneous response to climate change highlights the need for more comprehensive studies on the subject and careful consideration for appropriate species and habitat management plans in northeastern montane regions. 

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