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M.D. Samuel

Publications and source records attributed to M.D. Samuel.

36 records · Page 2Linked to original sources
USGS2000

Lead exposure in American black ducks after implementation of non-toxic shot

Lead poisoning from the ingestion of spent shotgun pellets has been recognized as an important disease of North American waterfowl since Bellrose's (1959) research >40 years ago. Nation-wide regulations banning the use of lead shot for waterfowl hunting were established in 1991. We compared the prevalence of lead exposure in American black ducks ( Anas rubripes ) wintering on 2 areas in Tennessee before (1986-88) and after the ban (1997-99) to assess the effect of the ban on lead shot on this species. Prevalence of elevated blood lead in black ducks declined by 44% from before (11.7% prevalence) to after (6.5% prevalence) the implementation of non-toxic shot. The reduction in lead exposure was pronounced in adult black ducks (from 14.3% to 5.3%). However, prevalence in lead exposure remained similar in juvenile black ducks (from 8.2% to 8.3%). Additional evidence from lead ingestion and lead poisoning mortality events also indicates that lead exposure has declined in waterfowl in the Mississippi flyway. We believe that lead ingestion will continue to decline, despite the persistence of lead shot in some wetlands. The impact of reduced lead exposure on waterfowl populations needs to be assessed.

Tennessee↗
USGS2000

Efficacy of a type C botulism vaccine in green-winged teal

We tested the efficacy of a single dose of Botumink toxoid for protecting wild green-winged teal (Anas crecca) during botulism epizootics caused by Clostridium botulinum type C. We challenged control and immunized ducks with four different doses of type C botulinum toxin to determine the LD50 for this species and to evaluate vaccine protection. Fewer immunized ducks were affected with botulism than control ducks, indicating that a single dose of Botumink toxoid could increase the survival of ducks during epizootics. However, the frequency of immunized ducks with signs of botulism increased with the challenge dose of botulinum toxin. Even at doses of botulinum toxin approximately 2 to 4 green-winged teal LD50, about 50% of the immunized ducks were affected. We believe an improved vaccine or a better delivery system is required to justify immunization of wild birds for experimental survival studies.

California, Utah↗
USGS1999

Antibodies against Pasteurella multocida in snow geese in the western arctic

To determine if lesser snow geese (Chen caerulescens caerulescens) are a potential reservoir for the Pasteurella multocida bacterium that causes avian cholera, serum samples and/or pharyngeal swabs were collected from > 3,400 adult geese breeding on Wrangel Island (Russia) and Banks Island (Canada) during 1993-1996. Pharyngeal swab sampling rarely (> 0.1%) detected birds that were exposed to P. multocida in these populations. Geese with serum antibody levels indicating recent infection with P. multocida were found at both breeding colonies. Prevalence of seropositive birds was 3.5% at Wrangel Island, an area that has no recorded history of avian cholera epizootics. Prevalence of seropositive birds was 2.8% at Banks Island in 1994, but increased to 8.2% during 1995 and 1996 when an estimated 40,000-60,000 snow geese were infected. Approximately 50% of the infected birds died during the epizootic and a portion of the surviving birds may have become carriers of the disease. This pattern of prevalence indicated that enzootic levels of infection with P. multocida occurred at both breeding colonies. When no avian cholera epizootics occurred (Wrangel Island, Banks Island in 1994), female snow geese (4.7%) had higher antibody prevalence than males (2.0%).

Journal of Wildlife Diseases↗
USGS1999

Avian cholera mortality in lesser snow geese nesting on Banks Island, Northwest Territories

Avian cholera is one of the most important diseases affecting waterfowl in North America, but little is known about its ecology and its impact on waterfowl populations. We documented avian cholera mortality in breeding lesser snow geese (Chen c. caerulescens) at the Egg River colony on Banks Island, Northwest Territories, Canada, in 1995 and 1996. Area of the breeding colony, core nesting area, and number of nesting geese were greater in 1996 (colony=7,537 ha, core area=1,581 ha, 401,000 nesting geese) than in 1995 (colony=6,637 ha, core area=996 ha, 318,000 nesting geese). Density of nesting geese also was greater in the core area during 1995 (120 geese/ha) than in 1996 (90 geese/ha). Pasteurella multocida (serotype 1) was cultured from the leg bones of adult snow goose carcasses collected after outbreaks. Mortality from avian cholera began during nesting and continued until birds dispersed at hatch. Mortality appeared to be in foci scattered throughout the nesting colony, but generally was greater where there were greater densities of nesting geese. We estimated that 30,000 and 20,000 geese died in 1995 and 1996, respectively, about 5-9% of the nesting colony. Between 1991 and 1997, at least 4 avian cholera outbreaks occurred at Banks Island. It appears that avian cholera has become endemic in this population of snow geese, and these birds have the potential to transmit the disease to other waterfowl, especially on wintering areas where waterfowl are very concentrated.

Northwest Terrritories↗
USGS1997

Pasteurella multocida serotype 1 isolated from a lesser snow goose

Pharyngeal swabs were collected from 298 lesser snow geese (Chen caerulescens caerulescens) at Banks Island (Northwest Territories. Canada) in the summer of 1994. Pasteurella multocida serotype 1 was isolated from an adult male bird and P. multocida serotype 3 was isolated from an adult female goose. Pathogenicity of the serotype 1 isolate was confirmed by inoculation in Pekin ducks (Anas platyrhynchos). The serotype 3 isolate was non-pathogenic in Pekin ducks. This is the first documented isolation of pathogenic P. multocida serotype 1 from apparently healthy wild snow geese.

Northwest Territories↗
USGS1996

Exposure of wild waterfowl to Mycoplasma anatis

We developed an ELISA procedure to assess the presence of M. Anatis-specific serum antibody in ducks. Sera from exposed and unexposed Pekin ducks (Anas platyrhynchos) were used to standardize tile ELISA and to establish reference ranges to classify ELISA results as exposed or not exposed. We conducted serological surveys of female waterfowl in the central and eastern United States between 1988 and 1992 to assess the frequency of exposure in wild waterfowl. Adult breeding mallards (Anas platyrhynchos), wintering mallards, and black ducks (Anas rubripes) had high prevalences of exposure to M. Anatis (25% to >80%). In comparison, none of the breeding adult canvasbacks (Aythya valisineria) had serum antibody levels indicating exposure. Approximately 50% of the juvenile mallards and black ducks were exposed to M. Anatis by 8 months of age, indicating high transmission rates among wild birds.

Journal of Wildlife Diseases↗
USGS1996

Technique for implanting radio transmitters subcutaneously in day-old ducklings

We developed and evaluated a surgical procedure for implanting radio transmitters in 1-d-old Canvasback (Aythya valisineria) ducklings. Transmitters (1.5 g) were implanted subcutaneously on the back of ducklings while under a general anesthetic, isoflurane, within a few hours of hatching. Evaluations indicate that the procedure is a reliable method for radio-marking ducklings.

Journal of Field Ornithology↗
USGS1995

Journal news

Statistical power (and conversely, Type II error) is often ignored by biologists. Power is important to consider in the design of studies, to ensure that sufficient resources are allocated to address a hypothesis under examination. Deter- mining appropriate sample size when designing experiments or calculating power for a statistical test requires an investigator to consider the importance of making incorrect conclusions about the experimental hypothesis and the biological importance of the alternative hypothesis (or the biological effect size researchers are attempting to measure). Poorly designed studies frequently provide results that are at best equivocal, and do little to advance science or assist in decision making. Completed studies that fail to reject Ho should consider power and the related probability of a Type II error in the interpretation of results, particularly when implicit or explicit acceptance of Ho is used to support a biological hypothesis or management decision. Investigators must consider the biological question they wish to answer (Tacha et al. 1982) and assess power on the basis of biologically significant differences (Taylor and Gerrodette 1993). Power calculations are somewhat subjective, because the author must specify either f or the minimum difference that is biologically important. Biologists may have different ideas about what values are appropriate. While determining biological significance is of central importance in power analysis, it is also an issue of importance in wildlife science. Procedures, references, and computer software to compute power are accessible; therefore, authors should consider power. We welcome comments or suggestions on this subject.

Journal of Wildlife Management↗
USGS1995

Seasonal ingestion of toxic and nontoxic shot by Canada geese

We used rates of ingested shot and elevated blood-lead levels (≥0.18 ppm) to estimate the proportion of Canada geese (Branta canadensis) exposed to lead on 3 study areas in Manitoba, Minnesota, and Missouri. Lead exposure was prevalent on all areas and was common after the hunting season closed, when up to 15% of geese could have been exposed to lead shot. However, the proportion of steel shot ingested by geese has increased during the past 2 decades. We suggest that lead exposure is still a source of indirect hunting mortality in Canada geese but project that the prevalence of lead exposure in the Eastern Prairie Population and other waterfowl populations will decrease as nontoxic shot regulations persist and hunters use steel or other nontoxic shot.

Minnesota, Missouri, Manitoba↗
USGS1994

Horvitz-Thompson survey sample methods for estimating large-scale animal abundance

Large-scale surveys to estimate animal abundance can be useful for monitoring population status and trends, for measuring responses to management or environmental alterations, and for testing ecological hypotheses about abundance. However, large-scale surveys may be expensive and logistically complex. To ensure resources are not wasted on unattainable targets, the goals and uses of each survey should be specified carefully and alternative methods for addressing these objectives always should be considered. During survey design, the impoflance of each survey error component (spatial design, propofiion of detected animals, precision in detection) should be considered carefully to produce a complete statistically based survey. Failure to address these three survey components may produce population estimates that are inaccurate (biased low), have unrealistic precision (too precise) and do not satisfactorily meet the survey objectives. Optimum survey design requires trade-offs in these sources of error relative to the costs of sampling plots and detecting animals on plots, considerations that are specific to the spatial logistics and survey methods. The Horvitz-Thompson estimators provide a comprehensive framework for considering all three survey components during the design and analysis of large-scale wildlife surveys. Problems of spatial and temporal (especially survey to survey) heterogeneity in detection probabilities have received little consideration, but failure to account for heterogeneity produces biased population estimates. The goal of producing unbiased population estimates is in conflict with the increased variation from heterogeneous detection in the population estimate. One solution to this conflict is to use an MSE-based approach to achieve a balance between bias reduction and increased variation. Further research is needed to develop methods that address spatial heterogeneity in detection, evaluate the effects of temporal heterogeneity on survey objectives and optimize decisions related to survey bias and variance. Finally, managers and researchers involved in the survey design process must realize that obtaining the best survey results requires an interactive and recursive process of survey design, execution, analysis and redesign. Survey refinements will be possible as further knowledge is gained on the actual abundance and distribution of the population and on the most efficient techniques for detection animals.

Transactions of the North American Wildlife and Na↗
USGS1992

A stochastic population model of mid-continental mallards

We developed a simulation model that integrates infonnation on factors affecting the population dynamics of mallards in the mid-continental region of the United States. In the model we vary age, body mass, and reproductive and molt status of simulated females. Females use several types of nesting and foraging habitat in 15 geographic areas. Deterministic and stochastic events cause mortality or attribute changes on a daily basis, depending on current attributes, habitat, area, calendar date, wetland conditions, temperature, and various mortality agents. Because the model encompasses the entire year, it can be used to examine cross-seasonal effects. A simulated increase in nest success from 0.14 to 0.17 changed the annual rate of population growth from -6% to -1 %. A simulated 75% reduction in lead poisoning changed the rate from -6% to -3%.

Book chapter↗
USGS1991

Effects of resighting errors on capture-resight estimates for neck-banded Canada geese

Biologists who study neck-banded Canada Geese (Branta canadensis) have used capture and resighting histories to estimate annual resighting rates, survival rates and the number of marked birds in the population. Resighting errors were associated with 9.4% ( n = 155) of the birds from a sample of Canada Geese neckbanded in the Mississippi flyway, 1974-1987, and constituted 3.0% ( n = 208) of the resightings. Resighting errors significantly reduced estimated resighting rates and significantly increased estimated numbers of marked geese in the sample. Estimates of survival rates were not significantly affected by resighting errors. Recommendations are offered for using neck-band characters that may reduce resighting errors.

Wisconsin↗