Paul F. Doherty

Factors Influencing Reporting and Harvest Probabilities in North American Geese

Abstract We assessed variation in reporting probabilities of standard bands among species, populations, harvest locations, and size classes of North American geese to enable estimation of unbiased harvest probabilities. We included reward (US

Occupancy of Mountain Plover and Burrowing Owl in Colorado

10,

Mallard Response to Experimental Walk-In and Shooting Disturbance

20,

Monitoring of the Flat-Tailed Horned Lizard With Methods Incorporating Detection Probability

30,

Survival and Breeding Transitions for a Reintroduced Bison Population: a Multistate Approach

50, or

Temporal Patterns of Apparent Leg Band Retention in North American Geese

100) and control (

Effects of hunting season structure, weather and body condition on overwintering mallard Anas platyrhynchos survival

0) banded geese from 16 recognized goose populations of 4 species: Canada (Branta canadensis), cackling (B. hutchinsii), Rosss (Chen rossii), and snow geese (C. caerulescens). We incorporated spatially explicit direct recoveries and live recaptures into a multinomial model to estimate reporting, harvest, and band-retention probabilities. We compared various models for estimating harvest probabilities at country (United States vs. Canada), flyway (5 administrative regions), and harvest area (i.e., flyways divided into northern and southern sections) scales. Mean reporting probability of standard bands was 0.73 (95% CI = 0.69–0.77). Point estimates of reporting probabilities for goose populations or spatial units varied from 0.52 to 0.93, but confidence intervals for individual estimates overlapped and model selection indicated that models with species, population, or spatial effects were less parsimonious than those without these effects. Our estimates were similar to recently reported estimates for mallards (Anas platyrhynchos). We provide current harvest probability estimates for these populations using our direct measures of reporting probability, improving the accuracy of previous estimates obtained from recovery probabilities alone. Goose managers and researchers throughout North America can use our reporting probabilities to correct recovery probabilities estimated from standard banding operations for deriving spatially explicit harvest probabilities.

Nest Success of Gunnison Sage-Grouse in Colorado, USA.

Abstract Concern over the decline of grassland birds has spurred efforts to increase understanding of grassland bird–habitat relationships. Previous studies have suggested that black-tailed prairie dogs (Cynomys ludovicianus) provide important habitat for shortgrass prairie avifauna, such as mountain plover (Charadrius montanus) and western burrowing owl (Athene cunicularia hypugaea), although such studies are lacking in Colorado (USA). We used methods to estimate occupancy (ψ) of mountain plover and burrowing owl on prairie dog colonies and other shortgrass prairie habitats in eastern Colorado. Mountain plover occupancy was higher on prairie dog colonies (ψ = 0.50, 95% CI = 0.36–0.64) than on grassland (ψ = 0.07, 95% CI = 0.03–0.15) and dryland agriculture (ψ = 0.13, 95% CI = 0.07–0.23). Burrowing owl occupancy was higher on active prairie dog colonies (ψ = 0.80, 95% CI = 0.66–0.89) compared with inactive colonies (ψ = 0.23, 95% CI = 0.07–0.53), which in turn was much higher than on grassland (ψ = 0.01, 95% CI = 0.00–0.07) and dryland agriculture (ψ = 0.00, 95% CI = 0.00–0.00). Mountain plover occupancy also was positively correlated with increasing amounts of prairie dog colony in the landscape. Burrowing owl occupancy was negatively correlated with increasing amounts of prairie dog colony in the surrounding landscape. Our results suggest that actions to conserve mountain plovers and burrowing owls should incorporate land management to benefit prairie dogs. Because managing for specific colony attributes is difficult, alternative management that promotes heterogeneity may ensure that suitable habitat is available for the guild of grassland inhabitants.

Anthropogenic Disturbances Drive Domestic Dog Use of Atlantic Forest Protected Areas

Abstract Spatial and temporal closures of anthropogenic activities are a common management strategy to increase waterfowl usage of an area. However, empirical evidence, specifically how individual waterfowl respond to disturbance, is lacking to support their efficacy. We exposed radiomarked mallards (Anas platyrhynchos) to walk-in, shooting, or no disturbance along the South Platte River corridor in Colorado, USA, from September to February during 2006–2007 and 2007–2008. Mallards exposed to shooting disturbance had greater mean flight distance after disturbance (FDAD) during September–November (4.58 km, 95% CI  =  3.55–5.62) than December–February (3.04 km, 95% CI  =  2.51–3.58) and were 35% and 17% greater than mean FDAD of mallards exposed to walk-in disturbance, respectively. Walk-in and shooting disturbance had a similar effect on return rates, and disturbed mallards had higher (0.09–0.41) movement probabilities away from and lower (0.15–0.20) probabilities of returning to treatment locations than controls. Probability of presence of disturbed mallards was 37% lower than controls during the daytime but was equal at night. Mallards exposed to walk-in (0.38 [95% CI  =  0.30–0.46]) and shooting (0.23 [95% CI  =  0.17–0.30] disturbance had low return rates the first afternoon after a disturbance compared to controls (0.71 [95% CI  =  0.65–0.77]). A high proportion of mallards exposed to walk-in (0.75 [95% CI  =  0.67–0.83]) and shooting (0.70 [95% CI  =  0.64–0.76]) disturbance returned to treatment locations in ≤1 day. Managers may be able to more effectively manage disturbance regimes by 1) accounting for surrounding lands within <10 km, especially lands within <5 km, 2) being conscientious when establishing regulations that will affect levels of disturbance 1–2 days after a previous disturbance, and 3) considering shooting and walking disturbance equally for refuge design.

A distance sampling approach to estimate density and abundance of gibbon groups

Abstract Difficulty in monitoring the flat-tailed horned lizard (Phrynosoma mcallii) has led to controversy over its conservation status. The difficulty in detecting this species has discouraged large-scale estimates of abundance and led to uncertainty over whether the species exists in population sizes of sufficient size for long-term persistence. We incorporated detection probability into monitoring of this species using closed mark–recapture and distance-sampling methods. Density estimation from mark–recapture abundance estimates was improved using an estimate of the proportion of time lizards were on the plot. We estimated the probability of detection on the line for distance sampling and adjusted density estimates accordingly. We estimated the populations of the Yuha Basin Management Area in 2002 and the East Mesa Management Area, Imperial County, California, USA, in 2003 to be 25,514 (95% CI 14,444–38,970) and 42,619 (95% CI 23,161–67,639), respectively. Two estimates of detection probability on the line in distance sampling by different methods were 0.45 and 0.65. Density estimates derived from distance analyses for 3 East Mesa Management Area plots and the Yuha Basin Management Area were 1.55 per ha (95% CI 0.64–3.76) and 0.41 per ha (95% CI 0.22–0.7), respectively. These are the first large-scale estimates of abundance and density for P. mcallii.