Large flood events were part of the historical disturbance regime within the lower basin of most large river systems around the world. Large flood events are now rare in the lower basins of most large river systems due to flood control structures. Endemic organisms that are adapted to this historical disturbance regime have become less abundant due to these dramatic changes in the hydrology and the resultant changes in vegetation structure. The Yuma Clapper Rail is a federally endangered bird that breeds in emergent marshes within the lower Colorado River basin in the southwestern United States and northwestern Mexico. We evaluated whether prescribed fire could be used as a surrogate disturbance event to help restore historical conditions for the benefit of Yuma Clapper Rails and four sympatric marsh-dependent birds. We conducted call-broadcast surveys for marsh birds within burned and unburned (control) plots both pre- and post-burn. Fire increased the numbers of Yuma Clapper Rails and Virginia Rails, and did not affect the numbers of Black Rails, Soras, and Least Bitterns. We found no evidence that detection probability of any of the five species differed between burn and control plots. Our results suggest that prescribed fire can be used to set back succession of emergent marshlands and help mimic the natural disturbance regime in the lower Colorado River basin. Hence, prescribed fire can be used to help increase Yuma Clapper Rail populations without adversely affecting sympatric species. Implementing a coordinated long-term fire management plan within marshes of the lower Colorado River may allow regulatory agencies to remove the Yuma Clapper Rail from the endangered species list.
We investigated home‐range and habitat preferences of Sonoran pronghorn (Antilocapra americana sonoriensis) from 1994 to 2002 as part of a recovery program. Home‐range size varied from 43–2,873 km2, with an average of 511±665.3 (SD) km2 (n=22). We classified vegetation into 3 associations: creosote (Larrea tridentata)‐bursage (Ambrosia spp.; CB), palo verde (Cercidium spp.)‐mixed cacti (PV), or palo verde‐chain fruit cholla (Opuntia fulgida; PVC). Individual pronghorn did not use vegetation associations similarly to each other (χ422=779, P < 0.001). Most pronghorn (n=17) used PVC more than expected and used CB and PV less than or equal to availability. Those pronghorn (n=5) that used CB more than expected or equal to availability had significantly larger home ranges (=1,321 km2) than those that preferred PVC (=272.7 km2, t=86, P=0.028). We pooled locations of all pronghorn to determine the influence of season and range condition (based on rainfall) on vegetation association preference. Range condition and season influenced vegetation association use by pronghorn. Pronghorn used CB more than expected during the cool season of 1997–1998. Pronghorn used washes more than expected in all seasons and range conditions (χ2=277, P < 0.001). This information is useful to managers planning recovery actions (i.e., forage enhancement, water development, and captive breeding).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.