John T. Ratti

Mallard Brood Survival and Wetland Habitat Conditions in Southwestern Manitoba

Although the primary mallard (Anas platyrhynchos) breeding area in North America has been greatly modified by agriculture, the relationship between habitat loss and mallard recruitment is not well understood. Consequently, we used radio telemetry to estimate brood and duckling survival for 69 mallard broods in southwestern Manitoba, 1987-89, and tested for effects of habitat conditions and hatching date. Annual brood and duckling survival averaged 0.49 (range =0.34−0.70) and 0.22 (range =0.16−0.26), respectively

Mallard brood movements and wetland selection in southwestern Manitoba

Wetland drainage has heavily impacted mallard (Anas platyrhynchos) breeding areas and decreased the amount of wetland area available to mallard broods. Also, habitat selection by mallard broods is poorly understood. Therefore, we investigated habitat use by mallard broods, monitored habitat availability, and tested for habitat selection by monitoring 29 mallard hens and their broods via radio telemetry in southwestern Manitoba, 1987-89. Habitat availability varied (P 0.10) by broods

Energy dynamics, foraging ecology, and behavior of prenesting greater white-fronted geese

We collected greater white-fronted geese (Anser albifrons frontalis) on their nesting grounds on the Yukon-Yuskokwim Delta, Alaska, when they arrived and again before incubation during 1986 and 1987. Body mass, water content, crude fat, and crude protein increased in female geese between arrival and incubation onset in 1986 and 1987 (P=0.0001, 0.0002, 0.0003, respectively). Body mass of male geese during prenesting did not change, but total fat content decreased by about 30%. Crude protein of males was different between years (P=0.0014). Female geese spent more time feeding than did males (P<0.001). Primary foods during the prenesting period were pendent grass (Arctophila fulva) shoots and arrowgrass (Triglochin palustris) bulbs

EFFECTS OF PREDATOR REMOVAL ON MALLARD DUCKLING SURVIVAL

Abstract We experimentally evaluated the effect of predator removal on mallard (Anas platyrhynchos) duckling survival in south-central Saskatchewan, Canada, in 2000 and 2001. Previous predator-removal research has focused on nest success, but our study was the first to document an effect on duckling survival. We compared 4 control sites (no predator removal) with 4 treatment sites where professional trappers removed common nest predators. Survival of 686 ducklings from 78 broods was determined using radiotelemetry and periodic counts of ducklings. Duckling survival was higher on predator-removal sites relative to control sites in 2000 and 2001 and negatively correlated with hatch date in 2000. Results of analyses including and excluding hatch date as a covariate suggest that hatch date was confounded with predator removal (i.e., predator removal influenced hatch dates). Based on these results, we concluded that duckling survival was affected by predator removal in 2 ways. First, predator removal increased duckling survival by removing predators that likely caused total brood loss. Second, in-the-year hatch date was negatively correlated with duckling survival, earlier average hatch dates on predator-removal areas contributed to increased duckling survival. Combining the 2 effects and averaging over years, 30-day duckling survival was 0.573 (90% CI: 0.492 to 0.657) on predator-removal sites and 0.357 (90% CI: 0.275 to 0.456) on control sites. We concluded that predator-removal efforts conducted primarily to increase nest success of upland-nesting ducks also increased survival of mallard ducklings.

Comparison of avian communities on restored and natural wetlands in north and south Dakota

We compared avian use of 39 restored and 39 natural wetlands in North and South Dakota during spring and summer of 1997 and 1998. Wetlands were widely distributed, but restored- and natural-wetland pairs were from the same geographic locale and had similar characteristics, including wetland size. We conducted paired comparisons between restored and natural wetlands for wetland-bird density, waterfowl-breeding pairs, and wetland-avian abundance, species richness, and diversity. We also compared abundance, species richness, and diversity of birds on upland areas adjacent to wetlands. Canada goose (avian scientific names in Appendix A), mallard, redhead, and ruddy duck had higher densities on restored wetlands. We failed to detect differences in overall avian abundance, species richness, or diversity between restored and natural wetlands. We conclude that restored wetlands in the Prairie Pothole Region supported similar avian communities with equal or higher abundances than those of natural wetlands.

Use of methoxyflurane to reduce nest abandonment of mallards

We used methoxyflurane anesthesia to reduce nest abandonment by incubating dabbling ducks trapped on nests. We anesthetized 80 individuals with only 2 abandonments following attachment of radio transmitters. This technique apparently reduces capture and handling trauma

Habitat Use and Home Range of Gray Partridge in Eastern South Dakota

Gray partridge (Perdix perdix) habitat use was studied in eastern South Dakota by monitoring 46 radio-tagged birds between 22 December 1978 and 21 August 1980. Partridge coveys used pastures in a winter with deep snow (56 cm, 1979) and row crops in a winter with little snow (4 cm, 1980). During spring dispersal, partridge used many different habitat types. Idle habitat (roadside, fencerows, shelterbelts) was used in late spring during the nesting period and small grain crops in early summer as broodrearing cover. Partridge used standing row crops during late summer after small grain harvest. They continued to use row crops after fall harvest. Partridge did not use different habitat types during 3 diurnal time periods. Mean home range was 96 ha (N = 8); however, individual home ranges were variable (SD = 110.6). Variability in home range may be related to season, weather, and stage in the partridge life cycle. J. WILDL. MANAGE. 46(3):580-587 Gray partridge are becoming more important as a game species in the northern prairies. In South Dakota, hunter harvest of partridge increased from 3,125 birds in 1970 to 69,170 in 1978 (South Dakota Dep. Game, Fish and Parks, unpubl. rep., 1980). Although partridge are an important wildlife resource, few data are available on their ecology in South Dakota. The objectives of this study were to examine seasonal habitat use and home range size of gray partridge in eastern South Dakota. We thank W. L. Tucker and G. C. White for assisting with statistical analysis and J. E. Dunn for providing the home range program. K. McElvain provided assistance with computer programming. W. Balda, D. Doudna, B. Gehring, J. Jasmer, E. Keyser, and D. Lundborg assisted with field work and R. P. Davison, L. D. Flake, C. G. Scalet, J. P. Weigand, and W. A. We tz reviewed drafts of the manuscript. We thank the study area landowners for their support and L. Ratti for editorial suggestions.

Long-term population analysis of gray partridge in eastern Washington

Recent studies reported that gray partridge (Perdix perdix) populations have declined throughout Europe and Asia. Gray partridge on the Palouse Prairie of Washington also have been reported to be in decline. Therefore, we analyzed densities of gray partridge on the Palouse Prairie of Washington to determine long-term population trends (1940-92). We also tested for density dependence in recruitment and fall-and-winter mortality rates and attempted to relate annual variation in recruitment and mortality to weather and habitat variables. Spring and/or fall estimates of density were available for 33 of 53 years and varied from 1.3 to 23.2 birds/km 2 in the spring and from 0.1 to 28.6 birds/km 2 in the fall. The populations return point from 1940 to 1954 was 3.45 birds/km 2 versus 6.72 birds/km 2 from 1982 to 1992, indicating that density was higher in the more recent period. Surprisingly, this result contrasts with a series of reports that indicated that the population was in serious decline. We detected density-dependent effects on recruitment rate, fall-and-winter mortality rate, and annual change in population size. Density dependence had the strongest effects on recruitment rate. Recruitment rate averaged 1.55 (SE = 0.27) but ranged widely (0.38-3.38). Fall-and-winter mortality averaged 0.29 (SE = 0.06). We were not able to explain variation in population-growth rate or fall-and-winter mortality rate using habitat and/or weather variables (P > 0.11). Under current habitat conditions, density typically will be 6.7 birds/km 2 in the spring and 10.4 birds/km 2 in the fall and can be expected to vary markedly independent of density. By combining available datasets, we developed a lengthy time series adequate for investigating long-term population dynamics. Such an approach may be possible and informative for other populations.

LINE TRANSECT ESTIMATES OF DENSITY AND THE WINTER MORTALITY OF GRAY PARTRIDGE

Line transect sampling was used to estimate density of gray partridge (Perdix perdix) on a 160- km2 study area in eastern South Dakota using newly developed estimation techniques. We traversed 272 transects during surveys in fall, mid-winter, and early spring 1979-80. Density estimates were 48 birds/km2 (SE = 10.3) in late fall, 21/km2 (SE = 5.0) in mid-winter, and 29/km2 (SE = 5.9) in early spring, but only fall to mid-winter estimates were different (P < 0.05). Partridge were behaviorally compatible with the assumptions of line transect sampling. We illustrate that this technique is more reliable than an index of abundance based on numbers observed per unit of distance traveled for appraising population fluctuations. Assuming a closed population and based on fall and mid-winter density estimates, early winter mortality was 56% (SE = 14). Our data indicate that estimates of gray partridge mortality based on reduction in

Bird Community Response to Vegetation Cover and Composition in Riparian Habitats Dominated by Russian Olive (Elaeagnus angustifolia)

Abstract Riparian systems in the western United States provide important habitat for bird communities during all times of the year. In recent decades, invasive plants, such as Russian olive (Elaeagnus angustifolia), have achieved broad distribution and local dominance in many western riparian areas, raising concerns over the loss of ecological function within these systems. In 2005 and 2006 we conducted avian point counts and surveyed vegetation cover at 95 points along the Snake and Columbia Rivers in southeastern Washington to investigate the effects of total woody vegetation cover and the relative proportion of Russian olive cover on breeding and wintering riparian bird communities. Our results indicated that riparian habitats dominated by Russian olive can support diverse and abundant bird communities, though cavity nesting species were noticeably sparse. Bird density and species richness were best explained by a quadratic relationship to total woody vegetation cover in both seasons, as was breeding bird community composition, with greatest density and richness in intermediate cover levels. We found no indication that the proportion of the woody vegetation comprised of Russian olive strongly influenced any of these bird community metrics. Given that Russian olive comprised 81.6% of the riparian vegetation in our study area, it is unclear from our results how Russian olive would affect bird communities in regions where native vegetation is more abundant. Regardless, complete eradication of Russian olive from riparian systems where the plant is a major component will reduce the overall habitat value for birds by eliminating significant structural complexity.