Martinez P.J.,711 Independent Avenue |
Martinez P.J.,U.S. Fish and Wildlife Service
Aquatic Invasions | Year: 2012
No crayfish species are native to the Colorado River Basin (CRB), including the portion of the state of Colorado west of the Continental Divide. Virile crayfish [Orconectes virilis (Hagen, 1870)], a recent invader in the middle Yampa River in northwestern Colorado, displayed an abrupt increase in abundance in the early 2000s, which coincided with a drought, a severe decline in the abundance of smallbodied and juvenile native fishes, and a dramatic increase in the abundance of nonnative smallmouth bass [Micropterus dolomieu (Lacepède, 1802)]. The annual density of virile crayfish was 6.4/m2 in 2005 and 9.3/m2 in 2006. The annual biomass density of virile crayfish was 9.0g/m2 in 2005 and 15.8 g/m2 in 2006, representing a riverwide biomass of 122 kg/ha, which equaled that of other macroinvertebrates and fish combined (120.7 kg/ha). Efforts to recover and preserve native fishes in the Upper Colorado River Basin (UCRB), particularly in the Yampa River, have been hampered by nonnative predatory fishes, but the implications of crayfish may have been overlooked and underestimated. Stream conditions during the drought apparently facilitated proliferation by virile crayfish in the middle Yampa River, likely contributing to hyperpredation on native fishes by invasive smallmouth bass. This trophic interaction between virile crayfish and smallmouth bass, in conjunction with regional projections for climate change, will likely make efforts to reduce the abundance and negative ecological impact of smallmouth bass in this ecosystem more difficult and costly. Given the nonnative status of all crayfishes in the CRB, and their invasive capacity and potential to negatively reconfigure native lotic food webs, all states in the UCRB should prohibit the importation, movement, sale, possession and stocking of any live crayfish. © 2012 The Author(s).
Bishop C.J.,17 W. Prospect Road |
Anderson Jr. C.R.,711 Independent Avenue |
Walsh D.P.,17 W. Prospect Road |
Bergman E.J.,17 W. Prospect Road |
And 2 more authors.
Journal of Wildlife Management | Year: 2011
Our understanding of factors that limit mule deer (Odocoileus hemionus) populations may be improved by evaluating neonatal survival as a function of dam characteristics under free-ranging conditions, which generally requires that both neonates and dams are radiocollared. The most viable technique facilitating capture of neonates from radiocollared adult females is use of vaginal implant transmitters (VITs). To date, VITs have allowed research opportunities that were not previously possible; however, VITs are often expelled from adult females prepartum, which limits their effectiveness. We redesigned an existing VIT manufactured by Advanced Telemetry Systems (ATS; Isanti, MN) by lengthening and widening wings used to retain the VIT in an adult female. Our objective was to increase VIT retention rates and thereby increase the likelihood of locating birth sites and newborn fawns. We placed the newly designed VITs in 59 adult female mule deer and evaluated the probability of retention to parturition and the probability of detecting newborn fawns. We also developed an equation for determining VIT sample size necessary to achieve a specified sample size of neonates. The probability of a VIT being retained until parturition was 0.766 (SE = 0.0605) and the probability of a VIT being retained to within 3 days of parturition was 0.894 (SE = 0.0441). In a similar study using the original VIT wings (Bishop et al. 2007), the probability of a VIT being retained until parturition was 0.447 (SE = 0.0468) and the probability of retention to within 3 days of parturition was 0.623 (SE = 0.0456). Thus, our design modification increased VIT retention to parturition by 0.319 (SE = 0.0765) and VIT retention to within 3 days of parturition by 0.271 (SE = 0.0634). Considering dams that retained VITs to within 3 days of parturition, the probability of detecting at least 1 neonate was 0.952 (SE = 0.0334) and the probability of detecting both fawns from twin litters was 0.588 (SE = 0.0827). We expended approximately 12 person-hours per detected neonate. As a guide for researchers planning future studies, we found that VIT sample size should approximately equal the targeted neonate sample size. Our study expands opportunities for conducting research that links adult female attributes to productivity and offspring survival in mule deer. © The Wildlife Society, 2011.
Thompson T.R.,University of Idaho |
Apa A.D.,711 Independent Avenue |
Reese K.P.,University of Idaho |
Tadvick K.M.,711 Independent Avenue
Journal of Wildlife Management | Year: 2015
Both species of North American sage-grouse (Centrocercus spp.) have experienced declines in distribution and abundance. Translocation of adult birds from a stable population to a small or declining population has been a management tool used by wildlife managers to support population persistence in these areas. Captive rearing chicks and releasing them into wild surrogate broods is an untested alternative to augment declining populations of sage-grouse. We developed techniques to successfully rear sage-grouse chicks in captivity, evaluated explanatory variables that could influence hatch and captive-rearing success, and estimated the survival of domestically hatched (DH) chicks to 28 days of age following introduction to a surrogate wild brood. We collected 304 eggs from radiomarked female greater sage-grouse (C. urophasianus) during 2004-2007 in 3 study areas in northwestern Colorado. Estimated hatching success of collected eggs was 0.745 (SE=0.022, 95% CI=0.700-0.786) and was negatively influenced by the number of days an egg was stored and the percent egg weight loss that occurred during storage and incubation. We monitored 175 DH chicks in captivity for 1-10 days before introduction and adoption into surrogate wild broods. Model-averaged captive-rearing success was 0.792 (SE=0.045, 95% CI=0.686-0.865) across years, and was positively influenced by initial chick mass at hatch and daily weight gain in captivity but negatively influenced by the number of days the egg was stored and advancing hatch date. We were able to radiomark and monitor 133 DH chicks adopted into surrogate wild broods until 28 days of age. Eighty-eight percent of DH chicks were successfully adopted within 24hours. Our overall estimate of DH chick survival to 28 days (0.423; 95% CI=0.257-0.587) was comparable to published wild-hatched chick survival. Predation and exposure-related deaths accounted for 26.3% and 25.6% of the known fates, respectively. Our captive-rearing protocols and techniques were successful for collecting greater sage-grouse eggs, hatching and rearing chicks in captivity, and releasing chicks into wild surrogate broods. This success further implies that captive rearing and release can be a potential management strategy to demographically and genetically reinforce or augment small populations of sage-grouse. © 2015 The Wildlife Society. © The Wildlife Society, 2015.