Entries in rare species (2)

Thursday
Dec212017

New Paper on Effects of Fire, Habitat and Climate on Regal Fritillary

TPOS notes:

 

In "Disentangling effects of fire, habitat, and climate on an endangered prairie-specialist butterfly," the authors present an analysis of long-term datasets on populations of an endangered species, habitat quality, and prescribed fire management.

 

Abstract:
Tallgrass prairie, arguably the most fire-dependent system in North America, is a Biome that has been essentially eliminated and is now exceedingly rare. Absent frequent disturbance, remnant tallgrass prairie rapidly converts to a dominant cover of woody plants. This creates unique challenges for conservation of prairie-specialist insects dependent on increasingly small and isolated habitats prone to direct and indirect threats from climate variability, habitat degradation, and management activities; or lack thereof. Regal fritillary butterflies (Speyeria idalia) exemplify this problem, with sharp population declines in recent decades and considerable disagreement on management practices, particularly in the use of prescribed burning to maintain habitat. Spanning 20-years (1997–2016), we evaluated regal fritillary populations within seven sites in relation to fire, habitat, and climate records to better understand these interacting effects on interannual and long-term population changes. Though fire had short-term negative effects on regal fritillary abundance, habitat quality was one of the most important factors explaining populations and was positively associated with prescribed fire. Burning every 3–5 years maximized regal fritillary abundance, but even annual burning was more beneficial to regal populations than no burning at all. Unburned refugia are important in maintaining populations, but creating and maintaining high quality habitat with abundant violets (Viola spp) and varied nectar sources, may be the most impactful management and conservation tool. Regal fritillary butterflies were consistently more than twice as abundant on high quality habitats and this relationship held across, and often dwarfed the effects of, various prescribed fire regimes or climate variability.

 

Keywords
Grasslands; Habitat quality; Pollinators; Prairie; Prescribed fire; Regal fritillary

 

Citation:

 

Richard A. Henderson, Jed Meunier, Nathan S. Holoubek, Disentangling effects of fire, habitat, and climate on an endangered prairie-specialist butterfly, Biological Conservation, Volume 218, February 2018, Pages 41-48, ISSN 0006-3207, https://doi.org/10.1016/j.biocon.2017.10.034.

 

Corresponding author: Richard A. Henderson, tpe.rhenderson "at" tds.net
Friday
Nov032017

"Landscape context drives breeding habitat selection by an enigmatic grassland songbird"

TPOS notes:

This study of habitat use by the rare Henslow's sparrow in eastern Kansas sampled grassland sites in the fragmented agricultural landscape ("Western Corn Belt Plains" ecoregion) as well as the extensive remnant grasslands of the Flint Hills. The species avoided woody vegetation and cropland, preferring landscapes with a higher proportion of grassland; for example, individuals were more likely to be detected in smalll patches of CRP embedded in rangeland than small patches of CRP surrounded by agricultural land. However, even in the Flint Hills the sparrows occupied less than 4% of the grassland area preferring CRP to intensively managed rangeland (typically grazed or burned then grazed). By using multiple sampling periods, researchers found that the sparrows were highly mobile within any given year, and in some cases occupied sites after mid-June that had been burned earlier in the year, though none were detected at completely burned sites during early season sampling.

First online 10/5/17 in Landscape Ecology.

Authors
Mark R. Herse, Michael E. Estey, Pamela J. Moore, Brett K. Sandercock, W. Alice Boyle

 

Abstract

 

Purpose
Wildlife conservation requires understanding how landscape context influences habitat selection at spatial scales broader than the territory or habitat patch.

 

Objectives
We assessed how landscape composition, fragmentation, and disturbance affected occurrence and within-season site-fidelity of a declining grassland songbird species (Henslow’s Sparrow, Ammodramus henslowii).

 

Methods
Our study area encompassed eastern Kansas (USA) and North America’s largest remaining tracts of tallgrass prairie. We conducted 10,292 breeding-season point-count surveys over 2 years, and related occurrence and within-season site-occupancy dynamics of sparrows to landscape attributes within 400-, 800-, and 1600-m radii.

 

Results
Sparrows inhabited < 1% of sites, appearing and disappearing locally within and between breeding seasons. Early in spring, sparrows responded to landscape attributes most strongly within 400-m radii, settling in areas containing > 50% unburned prairie. Later in summer, sparrows responded to landscape attributes most strongly within 800-m radii, settling in areas containing > 50% unfragmented prairie, including sites burned earlier the same year. Sparrows avoided landscapes containing woody vegetation, disappeared from hayfields after mowing, and were most likely to inhabit landscapes containing Conservation Reserve Program (CRP) fields embedded within rangeland.

 

Conclusions
Landscape context influenced habitat selection at spatial scales broader than both the territory and habitat patch. Protecting contiguous prairies from agricultural conversion and woody encroachment, promoting CRP enrollment, and maintaining portions of undisturbed prairie in working rangelands each year are critical to reversing the conservation crisis in North America’s remaining grasslands. As landscape change alters natural areas worldwide, effective conservation requires suitable conditions for threatened species at multiple spatial scales.

 

Link to article: http://rdcu.be/x2OX

 

Citation

 

Herse, M.R., Estey, M.E., Moore, P.J. et al. Landscape Ecol (2017). https://doi.org/10.1007/s10980-017-0574-z