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Trap Nights (trap + night)
Selected AbstractsSpatial distribution of vectors of Ross River virus and Barmah Forest virus on Russell Island, Moreton Bay, QueenslandAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002Jason AL Jeffery Abstract We used a network of 20 carbon dioxide- and octenol-supplemented light traps to sample adult mosquitoes throughout Russell Island in southern Moreton Bay, south-east Queensland. Between February and April 2001, an estimated 1365 564 adult female mosquitoes were collected. In contrast to an average catch of 9754 female mosquitoes per trap night on Russell Island, reference traps set on Macleay Island and on the mainland returned average catches of 3172 and 222, respectively. On Russell Island, Ochlerotatus vigilax (Skuse), Coquillettidia linealis (Skuse), Culex annulirostris Skuse and Verrallina funerea (Theobald), known or suspected vectors of Ross River (RR) and/or Barmah Forest (BF) viruses, comprised 89.6% of the 25 taxa collected. When the spatial distributions of the above species were mapped and analysed using local spatial statistics, all were found to be present in highest numbers towards the southern end of the island during most of the 7 weeks. This indicated the presence of more suitable adult harbourage sites and/or suboptimal larval control efficacy. As immature stages and the breeding habitat of Cq. linealis are as yet undescribed, this species in particular presents a considerable impediment to proposed development scenarios. The method presented here of mapping the numbers of mosquitoes throughout a local government area allows specific areas that have high vector numbers to be defined. [source] Evaluating the Predicted Local Extinction of a Once-Common MouseCONSERVATION BIOLOGY, Issue 4 2005OLIVER R.W. PERGAMS Chicago; declinación de especies comunes; extinción pronosticada; Peromyscus leucopus; Peromyscus maniculatus bairdii Abstract:,In an earlier paper (Pergams & Nyberg 2001) we found that the proportion of the prairie deer mouse (Peromyscus maniculatus bairdii), among all local Peromyscus museum specimens collected in the Chicago region, had significantly declined over time. This proportion changed from about 50% before 1900 to <10% in the last 25 years. Based on this proportion a regression model predicted the local extinction of the prairie deer mouse in 2009. To evaluate that prediction, we estimated current deer mouse abundance by live trapping small mammals at 15 preserves in Cook and Lake counties, Illinois (USA) at which prairie deer mice had previously been caught or that still contained their preferred open habitat. In 1900 trap nights, 477 mammals were caught, including 251 white-footed mice (P. leucopus), but only one prairie deer mouse. The observed proportion of Peromyscus that were prairie deer mice, 0.4%, was even lower than the 4.5% predicted for 2000. Here we also introduce a simple, new community proportions model, which for any given geographic region compares the proportions of species recently caught with the proportions of species in museums. We compared proportions of seven species collected in Cook and Lake counties and examined by Hoffmeister (1989) with proportions of these species that we caught. Ten percent of the museum community was prairie deer mice, but only 0.2% of our catch was. The current local scarcity of the prairie deer mouse is consistent with the regression-based prediction of its eminent local extinction. More conservation attention should be paid to changes in relative abundance of once-common species. Resumen:,En un artículo previo (Pergams & Nyberg 2001) encontramos que la proporción de Peromyscus maniculatus bairdii, entre todos los especimenes de museo de Peromyscus recolectados en la región de Chicago, había declinado significativamente. Esta proporción cambió de 50% antes de 1900 a <10% en los últimos 25 años. Con base en esta proporción, un modelo de regresión pronosticó la extinción local de P. m. bairdii en 2009. Para evaluar esa predicción, estimamos la abundancia actual de P. m. bairdii mediante el trampeo de mamíferos pequeños en 25 reservas en los condados Cook y Lake, Illinois (E.U.A.) en las que se había capturado a P. m. bairdii previamente o que aun contenían su hábitat abierto preferido. En 1900 noches-trampa, capturamos a 477 mamíferos, incluyendo a 251 P. leucopus pero solo a un P. m. bairdii. La proporción observada de P. m. bairdii, 0.4%, fue menor a 4.5% pronosticado para 2000. Aquí también introducimos un modelo, nuevo y sencillo, de proporciones de la comunidad que compara, para cualquier región geográfica, las proporciones de especies recientemente capturadas con la proporciones de especies en los museos. Comparamos las proporciones de siete especies recolectadas en los condados Cook y Lake y examinadas por Hoffmeister (1989) con las proporciones de especies que capturamos. Diez por ciento de la comunidad de museos era P. m. bairdii, pero solo 0.2% de nuestra muestra lo fue. La actual escasez local de P. m. bairdii es consistente con la predicción de su inminente extinción local con base en la regresión. La conservación debe prestar mayor atención a los cambios en la abundancia relativa de una especie anteriormente común. [source] Elevational gradients of small mammal diversity on the northern slopes of Mt. Qilian, ChinaGLOBAL ECOLOGY, Issue 6 2003Jun Sheng Li ABSTRACT Aim, Small mammal species richness and relative abundance vary along elevational gradients, but there are different patterns that exist. This study reports the patterns of distribution and abundance of small mammals along the broader elevational gradient of Mt. Qilian range. Location, The study was conducted in the Mt. Qilian range, north-western China, from June to August 2001. Methods, Removal trapping was conducted using a standardized technique at 7 sites ranging between 1600 and 3900 m elevation within three transects. Correlation, regression and graphical analyses were used to evaluate the diversity patterns along this elevational gradient. Results, ,In total, 586 individuals representing 18 nonvolant small mammal species were collected during 20 160 trap nights. Species composition was different among the three transects with 6 (33%) of the species found only within one transect. Elevational distribution and relative abundance of small rodents showed substantial spatial variation, with only 2 species showing nonsignificant capture frequencies across elevations. Despite these variations, some general patterns of elevational distribution emerged: humped-shape relationships between species diversity and elevation were noted in all three transects with diversity peaks at middle elevations. In addition, relative abundance was negatively correlated with elevation. Conclusions, Results indicate that maximum richness and diversity of nonvolant small mammals occurred at mid-elevations where several types of plants reached their maximum diversity and primary productivity, and where rainfall and humidity reached a maximum. It is demonstrated that the mid-elevation bulge is a general feature of at least a large portion of the biota on the Mt. Qilian range. [source] Evaluating capture,recapture population and density estimation of tigers in a population with known parametersANIMAL CONSERVATION, Issue 1 2010R. K. Sharma Abstract Conservation strategies for endangered species require accurate and precise estimates of abundance. Unfortunately, obtaining unbiased estimates can be difficult due to inappropriate estimator models and study design. We evaluate population,density estimators for tigers Panthera tigris in Kanha Tiger Reserve, India, using camera traps in conjunction with telemetry (n=6) in a known minimum population of 14 tigers. An effort of 462 trap nights over 42 days yielded 44 photographs of 12 adult tigers. Using closed population estimators, the best-fit model (program capture) accounted for individual heterogeneity (Mh). The least biased and precise population estimate ( (SE) []) was obtained by the Mh Jackknife 1 (JK1) [14 (1.89)] in program care -2. Tiger density ( (SE) []) per 100 km2 was estimated at 13 (2.08) when the effective trapping area was estimated using the half mean maximum distance moved (1/2 MMDM), 8.1 (2.08), using the home-range radius, 7.8 (1.59), with the full MMDM and 8.0 (3.0) with the spatial likelihood method in program density 4.1. The actual density of collared tigers (3.27 per 100 km2) was closely estimated by home-range radius at 3.9 (0.76), full MMDM at 3.48 (0.81) and spatial likelihood at 3.78 (1.54), but overestimated by 1/2 MMDM at 6 (0.81) tigers per 100 km2. Sampling costs (Rs. 450 per camera day) increased linearly with camera density, while the precision of population estimates leveled off at 25 cameras per 100 km2. At simulated low tiger densities, a camera density of 50 per 100 km2 with an effort of 8 trap nights km,2 provided 95% confidence coverage, but estimates lacked precision. [source] | ||||||||||