DISTRIBUTION, DIET, AND PREVALENCE OF AMPHIBIAN CHYTRID FUNGUS IN NON-NATIVE AMERICAN BULLFROGS (LITHOBATES CATESBEIANUS) AT THE VALENTINE NATIONAL WILDLIFE REFUGE, NEBRASKA, USA

American Bullfrogs (Lithobates catesbeianus) have been widely introduced beyond their native range in North America and can negatively affect organisms in wetland environments via a suite of mechanisms including interspecific interactions and disease transmission. Bullfrogs were introduced to the Valentine National Wildlife Refuge in the Sandhill Region of Nebraska, USA, yet little is known regarding their distribution, abundance, and potential effects on other vertebrates in the Refuge. Surveys in 1991-1992 documented bullfrogs in only one lake by the Refuge headquarters, and anecdotal historical observations indicated that bullfrogs were present primarily in lakes open to public fishing. In 2012, we determined the distribution of bullfrogs across the Refuge, examined their diets, and sampled them for the occurrence of the pathogenic fungus, Batrachochytrium dendrobatidis. We documented that bullfrogs were almost ubiquitous across the Refuge lakes and wetlands. From diet analyses, we observed that adult bullfrogs consumed several vertebrate species on the Refuge including: a Blanding’s Turtle (Emydoidea blandingii), small bullfrogs, an unidentifiable frog species, and numerous invertebrates, including crayfish. The amphibian chytrid fungus was prevalent on the refuge with 73.7% of bullfrogs testing positive for the fungus in early June and 6.3% in late June-July. Preliminary data indicate that bullfrogs likely have already affected interspecific interactions with native amphibians via predation, competition, and/or disease transmission. Bullfrogs likely cannot be eradicated from the Refuge, but expanding the season of harvest of bullfrogs might reduce their abundance, which may benefit native amphibians and reptiles

High Abundance of Nesting Long-Eared Owls in North Dakota

The long-eared owl (Asio otus) is a secretive, poorly understood species in the Great Plains of the United States and Canada. In North Dakota the long-eared owl has been considered a species of special concern (Petersen 1991), due mainly to lack of information on its occurrence and nesting status. We discovered 39 long-eared owl nests while searching for Cooper\u27s hawk (Accipiter cooperii) nests in northwestern and north central North Dakota during April and May 2000. Long-eared owl nests mainly were observed at J. Clark Salyer and Des Lacs National Wildlife Refuges (NWRs) in the Souris River basin (for study area descriptions see Nenneman et al. 2002) and at Lostwood NWR on the Missouri Coteau landform (Murphy 1993). These 39 nests exceed the total of all state breeding records for the long-eared owl through the early 1970\u27s (Stewart 1975: 159). During 1994 to 1999 we annually found 2 to 12 long-eared owl nests while searching for Cooper\u27s hawk nests in approximately the same area of North Dakota

Effects of Management Practices on Grassland Birds: Grasshopper Sparrow

Grasshopper Sparrow (Ammodramus savannarum): Breeding range Suitable habitat Area requirements Brown-headed Cowbird brood parasitism Breeding-season phenology and site fidelity Species’ response to management Management Recommendations Habitat Characteristic

Effects of Management Practices on Grassland Birds: Sprague’s Pipit

Sprague’s Pipit (Anthus spragueii): Breeding range Suitable habitat Area requirements Brown-headed Cowbird brood parasitism Breeding-season phenology and site fidelity Species’ response to management Management Recommendations Habitat Characteristic

Effects of Management Practices on Grassland Birds: Sprague’s Pipit

Sprague’s Pipit (Anthus spragueii): Breeding range Suitable habitat Area requirements Brown-headed Cowbird brood parasitism Breeding-season phenology and site fidelity Species’ response to management Management Recommendations Habitat Characteristic

Effects of Management Practices on Grassland Birds: Grasshopper Sparrow

Grasshopper Sparrow (Ammodramus savannarum): Breeding range Suitable habitat Area requirements Brown-headed Cowbird brood parasitism Breeding-season phenology and site fidelity Species’ response to management Management Recommendations Habitat Characteristic

COMMON RAVEN NESTS IN NORTH DAKOTA AFTER 100-YEAR HIATUS

Our observations represent the first documented nesting by the common raven in North Dakota since the late 1800\u27s. Houston (1977) suggested that the expansion of the American crow onto the Canadian prairies was limited by the scarcity of trees for nest sites, which also might have limited the extent of the common raven. Aspen woodland has increased substantially in and around J. Clark Salyer National Wildlife Refuge since European settlement, due primarily to fire suppression and extirpation of large herbivores (Grant and Murphy 2005). Thus, plausibly these increases in woodland habitat might be providing nest sites necessary for the common raven to recolonize the region. Conversely, the common raven is currently a year-round resident in northern McHenry County, in the Turtle Mountains (Bottineau and Rolette counties), and in the Pembina Hills (Pembina and Cavalier counties), areas which represented extensive natural woodland areas prior to settlement of the region. Common raven numbers have increased during the second half of the twentieth century, and the common raven has returned to parts of its previous range (Boarman and Heinrich 1999). Indeed, analysis of Breeding Bird Survey routes from 1966 through 2003 indicates an increasing population trend for the common raven across most of its range in North America. An increase of greater than 1.5% change per year is indicated for neighboring northwestern Minnesota, southern Manitoba, and southeastern Saskatchewan (Sauer et al. 2008). Possibly, these opportunistic Corvids are adapting to and expanding into previously unoccupied habitats

Common carp abundance, biomass, and removal from Dewey and Clear lakes on the Valentine National Wildlife Refuge: Does trapping and removing carp payoff?

Common carp Cyprinus carpio is a nonnative invasive nuisance species to North America. Many authors have documented the detrimental affects of common carp invasions on waterfowl habitats (Chamberlain 1948; Robel 1961), game fish habitat (Cahn 1929), and the overall decline in native fishes (Bernstein and Olson 2001; Koehn 2004). Common carp reduce water quality by mobilizing nutrients and increasing turbidity; therefore, increasing phytoplankton biomass and reducing zooplankton biomass and rooted aquatic vegetation (Lougheed et al. 1998). Common carp are capable of rapidly colonizing shallow lakes and altering a body of water from a clear stable state, dominated by submergent vegetation to a more turbid state, dominated by phytoplankton (Northcote 1988; Parkos et al. 2003). Management and control of common carp has been well documented through much of North America (Meronek et al. 1996; Wydoski and Wiley 1999) with millions of dollars invested on research and control (Pimentel et al. 2000). Removal projects included mechanical harvest by netting (Ritz 1987; Pinto et al. 2005), water level manipulation to disrupt spawning (Summerfelt 1999), exclusion from spawning habitat (Lougheed and Chow-Fraser 2001), and piscicide application (Meronek et al. 1996). Northern pike Esox lucius have additionally been used as a biological tool to control common carp recruitment in the Sandhill lakes in Nebraska (Paukert et al. 2003). All methods of carp control have had varying degrees of success (Meronek et al. 1996). Common carp gained access to the U.S. Fish and Wildlife Service (USFWS), Valentine National Wildlife Refuge (NWR) lake system through Gordon Ditch, which was dug during the 1930\u27s (Wanner 2009). The ditch was plugged shortly after completion to eliminate fish movement onto the Refuge. Refuge lakes have a long history of chemical renovation to remove common carp (Wanner 2009). For approximately five years after renovation and the re-stocking of game fish, angling is excellent, waterfowl use is high; however, both decline soon after carp recolonization and subsequent habitat degradation (M. Lindvall, Valentine NWR, personal communication). Fisheries biologists from the USFWS and Nebraska Game and Parks Commission (NGPC) have also experimented with the use of northern pike and largemouth bass Micropterus salmoides to control common carp recruitment. Early attempts were unsuccessful because northern pike were introduced after carp populations were well established and subsequently the population and individual fish were too large to be controlled by predation (Wanner 2009). Common carp recruitment in the Refuge lakes is low due to predation or other abiotic factors (Phelps et al. 2008). Common carp have also been physically removed on Valentine NWR lakes by releasing water through control structures between lakes, luring fish into ditches during spawning migrations where they are subsequently trapped. In the ditches between Whitewater and Dewey lakes and Dewey and Clear lakes (Figure 1), thousands of common carp, with an estimated biomass of several tons, were trapped in 1993 and 2008 (Wanner 2009). Trapping was also attempted in 2003 with little success due to scour holes around the trap that allowed carp to escape (M. Nenneman, unpublished data). These methods of controlling common carp have never been thoroughly evaluated; therefore, the objectives of this study were to 1) estimate abundance, biomass, and size structure of common carp in Dewey Lake, 2) estimate the proportion of the abundance, biomass, and size structure of the common carp removed from the lake during the trapping operation, and 3) monitor water quality and carp relative abundance before and after carp removal

COMMON RAVEN NESTS IN NORTH DAKOTA AFTER 100-YEAR HIATUS

Our observations represent the first documented nesting by the common raven in North Dakota since the late 1800\u27s. Houston (1977) suggested that the expansion of the American crow onto the Canadian prairies was limited by the scarcity of trees for nest sites, which also might have limited the extent of the common raven. Aspen woodland has increased substantially in and around J. Clark Salyer National Wildlife Refuge since European settlement, due primarily to fire suppression and extirpation of large herbivores (Grant and Murphy 2005). Thus, plausibly these increases in woodland habitat might be providing nest sites necessary for the common raven to recolonize the region. Conversely, the common raven is currently a year-round resident in northern McHenry County, in the Turtle Mountains (Bottineau and Rolette counties), and in the Pembina Hills (Pembina and Cavalier counties), areas which represented extensive natural woodland areas prior to settlement of the region. Common raven numbers have increased during the second half of the twentieth century, and the common raven has returned to parts of its previous range (Boarman and Heinrich 1999). Indeed, analysis of Breeding Bird Survey routes from 1966 through 2003 indicates an increasing population trend for the common raven across most of its range in North America. An increase of greater than 1.5% change per year is indicated for neighboring northwestern Minnesota, southern Manitoba, and southeastern Saskatchewan (Sauer et al. 2008). Possibly, these opportunistic Corvids are adapting to and expanding into previously unoccupied habitats