Modeling the effects of environmental disturbance on wildlife communities: avian responses to prescribed fire

Abstract

Prescribed fire is a management tool used to reduce fuel loads on public lands in forested areas in the western United States. Identifying the impacts of prescribed fire on bird communities in ponderosa pine (Pinus ponderosa) forests is necessary for providing land management agencies with information regarding the effects of fuel reduction on sensitive, threatened, and migratory bird species. Recent developments in occupancy modeling have established a framework for quantifying the impacts of management practices on wildlife community dynamics. We describe a Bayesian hierarchical model of multi-species occupancy accounting for detection probability, and we demonstrate the model's usefulness for identifying effects of habitat disturbances on wildlife communities. Advantages to using the model include the ability to estimate the effects of environmental impacts on rare or elusive species, the intuitive nature of the modeling, the incorporation of detection probability, the estimation of parameter uncertainty, the flexibility of the model to suit a variety of experimental designs, and the composite estimate of the response that applies to the collection of observed species as opposed to merely a small subset of common species. Our modeling of the impacts of prescribed fire on avian communities in a ponderosa pine forest in Washington indicate that prescribed fire treatments result in increased occupancy rates for several bark-insectivore, cavity-nesting species including a management species of interest, Black-backed Woodpeckers (Picoides arcticus). Three aerial insectivore species, and the ground insectivore, American Robin (Turdus migratorius), also responded positively to prescribed fire, whereas three foliage insectivores and two seed specialists, Clark's Nutcracker (Nucifraga columbiana) and the Pine Siskin (Carduelis pinus), declined following treatments. Land management agencies interested in determining the effects of habitat manipulations on wildlife communities can use these methods to provide guidance for future management activities.

Detection biases yield misleading patterns of species persistence and colonization in fragmented landscapes

“…This is of important concern when considering that using just one annual or seasonal point count is the most widely applied protocol for monitoring bird communities (Forcey et al 2006). Our results lend support to the utility of dynamic, multispecies occupancy models to characterize spatial patterns of habitat use across species within a community (Russell et al 2009, Ruiz-Gutierrez et al 2010.…”

“…This can lead to an improved composite analysis of species groups (in this case LOW, MED, and HIGH FD species) as well as more precise estimates for individual species (Sauer and Link 2002, Kéry and Royle 2008, Russell et al 2009). Both the model that incorporated detection and the one that assumed perfect detection included an additional, grouplevel component that linked together speciesspecific parameters, within FD categories, with a common distribution (Dorazio et al 2006, Royle andDorazio 2008).…”

Detecting diversity: emerging methods to estimate species diversity

“…Birds have been the primary target [7,35,54,60], but applications include amphibians [61,62], freshwater and reef fish [56,63,64], and invertebrates [31,32,65]. MSOM estimation…”

Occupancy modeling of Black-backed Woodpeckers on burned Sierra Nevada forests

“…Highseverity stand-replacing wildfires have been suggested to be particularly important for this species (Hutto 1995, Murphy and Lehnhausen 1998, Kotliar et al 2002, Smucker et al 2005, Hanson and North 2008, with habitat quality peaking within the first few years of a high-severity fire (Murphy and Lehnhausen 1998, Saab et al 2007, Nappi and Drapeau 2009. However, the species may also respond positively to lower intensity fires such as controlled burns (Russell et al 2009), and it also occurs to some extent in unburned forests (Dixon andSaab 2000, Tremblay et al 2009). Habitat heterogeneity, with low-severity and unburned areas interspersed with more severely burned patches, may be important in maintaining the quality of woodpecker habitat beyond the first few years post fire (Nappi et al 2010).…”