Publications

We applied Hyperion sensor satellite data acquired by the National Aeronautics and Space Administration’s Earth Observing-1 (EO-1) satellite in conjunction with reconnaissance surveys to map the occurrences of the invasive Chinese tallow tree (Triadica sebifera) in the Toledo Bend Reservoir study area of northwestern Louisiana and northeastern Texas. The rationale for application of high...

Salt concentrations in lakes are dynamic. In the western United States, water diversions have caused significant declines in lake levels resulting in increased salinity, placing many aquatic species at risk (Galat and Robinson 1983, Beutel et al. 2001). Severe droughts can have similar effects on salt concentrations and aquatic communities (Swanson et al. 2003). Conversely, large inputs...

“Dave, would you do another legal declaration on the wolf for us?” The weary voice on the phone belonged to Mike Jimenez, Northern Rocky Mountain Wolf Management and Science Coordinator for the U.S. Fish and Wildlife Service (FWS). He was calling from Wyoming to ask me to prepare a document to address a legal challenge to the FWS’s August 2012 delisting of the wolf (Canis lupus) in...

The Rainwater Basin in Nebraska has been a historic staging area for midcontinent greater white-fronted geese (Anser albifrons frontalis) since the 1950s and, in the mid-1990s, millions of midcontinent lesser snow geese (Chen caerulescens caerulescens) expanded their spring migration route to include this region. In response to speculation that snow geese may be in direct competition...

Theory has predicted, and many experimental studies have confirmed, that resident plant species richness is inversely related to invisibility. Likewise, potential invaders that are functionally similar to resident plant species are less likely to invade than are those from different functional groups. Neither of these ideas has been tested in the context of an operational prairie...

Unlike most raptors, the Swainson's Hawk (Buteo swainsoni) migrates long distances between breeding and wintering ranges, which elevates the importance of stopover sites for foraging. We conducted three years of fall surveys in the Southern High Plains of Texas. Migrant Swainson's Hawks moved through the area mostly between July and mid-October, peaking in September. Subadults tended to...

No abstract available.

Recruitment is a key factor influencing duck population dynamics. Understanding what regulates recruitment of ducks is a prerequisite to informed habitat and harvest management. Quantity of May ponds (MP) has been linked to recruitment and population size (Kaminski and Gluesing 1987, Raveling and Heitmeyer 1989). However, wetland productivity (quality) is driven by inter-annual...

“Is Science in Danger of Sanctifying the Wolf” (Mech, 2012), contends that some scientists have claimed that wolf (Canis lupus) restoration has led to many ecological benefits lower in the food chain but that other scientists have questioned the evidence for those claims. Furthermore, my article claims that “the media become complicit [in promoting positive studies about wolves] by...

Introduction The effects of climate change on the natural resources protected by Parks will likely be substantial, but geographically variable, due to local variation in climate trajectories and differences among ecosystems in their vulnerability to climate change. The projections of general circulation models (GCMs) indicate the possible magnitude and direction of future climate change...

A five-day odyssey, spanning 58 hours without decent sleep or meals, taught these researchers one thing-how not to find a wolf den.

1.The management and removal of invasive species may give rise to unanticipated changes in plant–pollinator mutualisms because they can alter the composition and functioning of plant–pollinator interactions in a variety of ways. To utilize a functional approach for invasive species management, we examined the restoration of plant–pollinator mutualisms following the large-scale removal of...