Avian relationships with wildfire at two dry forest locations with different historical fire regimes

Abstract

Wildfire is a key factor influencing bird community composition in western North American forests. We need to understand species and community responses to wildfire and how responses vary regionally to effectively manage dry conifer forests for maintaining biodiversity. We compared avian relationships with wildfire burn severity between two dry forest locations of Arizona and Idaho. We predicted different responses to wildfire between locations due to regional differences in historical fire regime. We conducted point count surveys for 3 yr following wildfire (Arizona: 1997–1999; Idaho: 2008–2010) and used multispecies hierarchical models to analyze relationships of bird occupancy with burn severity. Consistent with our prediction for mixed‐severity fire regimes characterizing the Idaho location, we observed proportionately more positive species occupancy relationships and, consequently, a positive species richness relationship with burn severity in Idaho. We also observed the opposite pattern in Arizona, which was congruent with our prediction for the low‐severity fire regime characterizing that location. Cavity nesters and aerial insectivores occupied more severely burned sites following wildfire, corresponding with predicted increases in nesting substrate and foraging opportunities for these species. In contrast, canopy‐nesting foliage gleaners and pine seed consumers exhibited negative relationships with burn severity. Our results were consistent with predictions based on species life histories and with patterns from the literature, suggesting generality of observed relationships and locational difference in relationships with wildfire. We therefore suggest that optimal management strategies for maintaining avian diversity could differ regionally. Specifically, intensive fuels management may be ecologically less appropriate for promoting biodiversity in areas such as the Idaho location where mixed‐severity wildfires and dense forest stands were historically more common.

Interacting and non‐linear avian responses to mixed‐severity wildfire and time since fire

“…, Latif et al. ), but we show that such conditions are similarly important for species associated with understory vegetation and shrubs, particularly after roughly a decade following fire. Forest managers should consider these lasting effects of high‐severity fire on shrub development and supporting shrub‐associated birds that are far less abundant in unburned forest.…”

“…Nonetheless, our results suggest that suppressing high-severity fire would negatively affect a number of species in the Sierra Nevada. Recent studies emphasize the value of mixed-severity fire for snagassociated species (Lorenz et al 2015, White et al 2015, Latif et al 2016), but we show that such conditions are similarly important for species associated with understory vegetation and shrubs, particularly after roughly a decade following fire. Forest managers should consider these lasting effects of high-severity fire on shrub development and supporting shrub-associated birds that are far less abundant in unburned forest.…”

“…However, disagreement remains regarding the historical relative contributions of low-, moderate-, and high-severity fire and the current departure from those historical levels (Marlon et al 2012, Ful e et al 2014, Hanson and Odion 2014. Yet, characterizing animal responses to fire can provide important insight toward both historical fire regimes and future forest management , Latif et al 2016, Dellasala et al 2017.…”

Relationships between Wildfire Burn Severity, Cavity-Nesting Bird Assemblages, and Habitat in an Eastern Ponderosa Pine Forest

“…The response of cavity-nesting birds to the legacy effects of mixed-severity wildfires has been observed in many western ponderosa pine forested regions (e.g., Saab and Dudley, 1998;Kotliar et al, 2007;Dudley et al, 2012), but less is known on how cavity-nesting birds respond to the legacy of mixed-severity wildfires in eastern ponderosa pine forests. Many cavity-nesting bird species tend to respond positively in abundance and occupancy likelihood to burned areas due to increased snags for nesting substrate or foraging opportunities (Saab et al, 2005;Kalies et al, 2010;Latif et al, 2016), though cavity-nesting species' responses to wildfire can also range from neutral to negative based on severity, time since fire, and region (Saab and Powell, 2005;Smucker et al, 2005;Fontaine and Kennedy, 2012). Cavity-nesting species responses to wildfires can also vary in different regions based on the historical fire regime (Latif et al, 2016).…”

“…Many cavity-nesting bird species tend to respond positively in abundance and occupancy likelihood to burned areas due to increased snags for nesting substrate or foraging opportunities (Saab et al, 2005;Kalies et al, 2010;Latif et al, 2016), though cavity-nesting species' responses to wildfire can also range from neutral to negative based on severity, time since fire, and region (Saab and Powell, 2005;Smucker et al, 2005;Fontaine and Kennedy, 2012). Cavity-nesting species responses to wildfires can also vary in different regions based on the historical fire regime (Latif et al, 2016). Therefore, understanding the response of cavity-nesting birds to habitat created following mixed-severity wildfire across different regions of ponderosa pine is of high relevance to understanding the avian ecology of these systems.…”