Disease or predation. Xxxxxx (1998) reported no available information on ectoparasites or infectious diseases in LPCs, although several endoparasites, including nematodes and cestodes are known to infect the species. The Lesser Prairie-Chicken Interstate Working Group (1997) concluded that, while density-dependent transmission of disease was unlikely to have a significant effect on LPC populations, a disease that was transmitted independently of density could have drastic effects. The avian reticuloendotheliosis virus (REV) is a viral disease documented in poultry, which has been found to cause considerable mortality in captive Attwater’s prairie-chickens (Tympanuchus cupido attwateri) and greater prairie-chickens (X. xxxxxx). In 1999 and 2000, researchers surveyed blood samples from 184 LPCs from three states to determine if REV was present in the species. However, all samples were negative, suggesting that REV may not be a serious problem for most wild populations of LPC (Xxxxxxxxxx et al. 2002). The impact of West Nile Virus (WNV) on the LPC is unknown. Ruffed grouse have been documented to harbor WNV infection rates similar to some corvids. For 130 ruffed grouse tested in 2000, all distant from known WNV epicenters, 21 percent tested positive. This was remarkably similar to American crows and blue jays (23 percent for each species), species with known susceptibility to WNV (Xxxxxxx et al. 2001). Recent analysis of the degree of threat to prairie grouse from parasites and infectious disease concluded that microparasitic infections that cause high mortality across a broad range of galliform hosts have the potential to extirpate small, isolated prairie grouse populations (Xxxxxxxx 2004). Currently, CEHMM is conducting a regional assessment of WNV within the indigenous populations of Chihuahuan ravens (Corvus cryptoleucus). Ravens were chosen as environmental sentinels for this study due to their omnivorous/scavenging nature and susceptibility to avian pathogens such as the WNV. Many of the nesting areas currently being investigated overlap with the known occupied range of the LPC. Data collected during this investigation will be made available in the event that WNV becomes a suspect in any suspicious LPC population decline. Prairie falcon (Falco mexicanus), northern harrier (Circus cyaneus), great-horned owl (Bubo virginianus), other unspecified raptors, and coyote (Canis latrans) have been identified as predators of LPC adults and chicks (Xxxxx et al. 1979; Merchant 1982; Hau...
Disease or predation. No information is available on the incidence of disease for any of the four beetle species. The only information available on predation is that nighthawks (Chordeiles sp.) have been observed preying on adult Xxxxxxxx’x dune scarabs at Big Dune (Xxxx 2010, p. 4; Service 2011a, p. 5). The scarabs were above ground as part of their mating activity, which is thought to be limited to a brief period during evenings in April to May (see ‘‘Biology and Population Abundance’’ section above). Except for this brief period of aboveground mating activity by the Xxxxxxxx’x dune scarab, the life cycle of this and the other three sand dune beetles occurs below ground. No information is available on predation of the beetles during belowground parts of their life cycle. We conclude that disease or predation is not a threat to any of the four beetle species.
Disease or predation. No information is available on the impact of disease on Page springsnail populations, and minimal specific information is available on predators. Potential predators of Page springsnails include migratory waterfowl (Anas spp.), aquatic invertebrates, and predatory fish. Xxxxxxxx (1991) examined the stomach contents of nonnative mosquitofish from the Oak Creek springs complex and found remnants of Page springsnail shells. Numerous species of predatory fish, including mosquitofish (Gambusia affinis), have occurred in, Xxxxxxx Xxxxx, including Xxxx Springs and Bubbling springs pond. In addition to nonnative fish, two species of nonnative snails (Chinese mystery snail Cipangopaludina chinensis, and decollate snail Rumina decollata), are sympatric with Page springsnails at Bubbling Springs and Page Springs hatchery. Exotic mollusks can be detrimental to native snails (Landye 1981), however it is unclear whether the nonnatives simply compete for resources or predate any life-stage of the Page springsnail. There is no definitive data available to conclude that competition is a limiting factor. In March 2001, non-native crayfish were discovered in a drainage ditch next to Bubbling Springs Pond (AGFD unpublished data). Crayfish are known predators of aquatic snails. (Xxxxxxxxx and Xxxxx 1996). Crayfish and other predators may negatively affect efforts to maintain extant populations of Page springsnails and future efforts to re-establish others.
Disease or predation. (Factor C) There is currently no information to indicate that disease has played a significant role in the past decline of the Sicklefin Redhorse. However, there are numerous fish diseases with the potential to seriously affect population levels (e.g., Spring Viremia, Columnaris, Aeromonas spp., Viral Hemorrhagic Septicemia). The introduction of nonnative diseases can be especially devastating to native fish species populations. Fish hatcheries/farms and hobbyist ponds in the watersheds of these rivers, especially those with direct links to streams in the systems, pose a significant threat unless adequate measures are implemented to prevent the introduction and spread of pathogens from these facilities/ponds. The early life stages (eggs, fry, and juveniles) of the Sicklefin Redhorse are likely preyed upon by a variety of other species. Predation by naturally occurring predators is a normal aspect of the population dynamics and is not considered to currently pose a threat to the species. However, the introduction of nonnative species could pose a significant threat to the Sicklefin Redhorse. Recently, nonnative Blueback Xxxxxxx (Xxxxx aestivalis) were introduced into the Hiwassee Reservoir, presumably by angler bait release. NCWRC biologists have documented a collapse of natural reproduction of Walleye (Sander vitreus) and White Bass (Xxxxxx chrysops), concurrent with increases in Blueback Xxxxxxx densities. Heavy Blueback Xxxxxxx predation of drifting eggs and early juveniles of both Walleye and White Bass has been observed in the transition zone between the free-flowing Hiwassee and Valley Rivers and the Hiwassee Reservoir. Blueback Xxxxxxx have been observed several miles upstream in the Valley and Nottely Rivers and have unobstructed access to the Hiwassee River upstream to the Mission Dam and lower Brasstown Creek. The occurrence of the Blueback Xxxxxxx has also been documented in the Nottely River, both upstream and downstream of Lake Nottely (X. Xxxxxxxx, GADNR, personal observation). Blueback Xxxxxxx have also been observed congregating at the mouths of other tributaries to the Hiwassee Reservoir in the months of March and April (above is condensed from personal observations by X. X. Xxxxxxx, X. X. Xxx, and X. X. Xxxxxx, NCWRC, 2005 and 2006). The presence of large numbers of known predators of drifting fish eggs and larvae at or near the time of Sicklefin Redhorse spawning and hatching poses a potentially significant threat. Further investigation i...
Disease or predation. 4.1.3.4 The inadequacy of existing regulatory mechanisms
Disease or predation. Because the number of southern Idaho ground squirrels at occupied sites is generally small, a disease outbreak could have a severe effect on this species (Xxxxx et al. 1995). Disease has been suggested as potentially contributing to the decline of these squirrels (Prescott and Yensen 1999, Yensen 1999), though no epizootic infestation has been noticed in either subspecies of Idaho ground squirrel (Yensen et al. 1996, Yensen and Xxxxxxx 1997). Blood analyses to determine whether pandemic diseases are present have not been done but should be considered in the future. Plague, a contagious bacterial disease found in rodents, has not been identified in southern Idaho ground squirrels (Yensen et al. 1996). The disease is of particular concern, once established, it could decimate the remaining small numbers of squirrels at occupied sites. Predation has not been suggested as one of the causes of the Southern Idaho ground squirrels’ decline; however, predators can have a severe impact on prey populations that occur at critically low numbers. For example, badgers have been known to extirpate entire colonies of Washington ground squirrels (Betts 1999).
Disease or predation. Impacts from Predators During radio telemetry experiments, pit fall studies, and surveys a number of predators were observed eating SDLs. A nesting ecology study conducted by Xxxx and Xxxxxxxxxx (2007) showed that 20 percent of female SDLs were predated upon by coachwhips (large, swift, diurnal snakes that feed primarily on SDLs). Twice coachwhips were found leaving pitfall buckets, once with a SDL in its mouth. Another predator, the loggerhead shrike (Xxxxxx ludovicanius) is found in the Mescalero Sands habitat. These small predatory birds occur in many habitats from remote deserts to suburban areas. They perch on trees, shrubs, poles, fences, and utility wires and swoop down to capture their prey. Loggerhead shrikes have weak feet that are of little use for grasping prey while eating. Instead, they impale their prey on sharp objects, such as xxxxx thorns or barbed-wire fences, and use their sharp bills to consume their catch (Xxxxxxxx 2006). SDLs have been found impaled on barbed-wire fences within shinnery oak dunes (Xxxxx and Xxxxxx 2003).
Disease or predation. The Service is not aware of diseases or parasites of the Xxxxxx Springs salamander. Primary predators of the Xxxxxx Springs salamander are believed to be predatory fish and crayfish; however, no information exists to indicate that predation poses a major threat to this species.
Disease or predation. Explore opportunities to design and implement a long-term monitoring plan (greater than 10 years) to determine the agent of herbivory on leaf and reproductive parts and whether herbivory significantly affects species viability.
Disease or predation
