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Dennis L. Orthmeyer

Publications and source records attributed to Dennis L. Orthmeyer.

5 recordsLinked to original sources
USGS2024

Mitigating risk: Predicting H5N1 avian influenza spread with an empirical model of bird movement

Understanding timing and distribution of virus spread is critical to global commercial and wildlife biosecurity management. A highly pathogenic avian influenza virus (HPAIv) global panzootic, affecting ~600 bird and mammal species globally and over 83 million birds across North America (Dec 2023), poses a serious global threat to animals and public health. We combined a large, long-term waterfowl GPS tracking dataset (16 species) with on-ground disease surveillance data (county-level HPAIv detections) to create a novel empirical model that evaluated spatiotemporal exposure and predicted future spread and potential arrival of HPAIv via GPS tracked migratory waterfowl through 2022. Our model was effective for wild waterfowl, but predictions lagged HPAIv detections in poultry facilities and among some highly impacted non-migratory species. Our results offer critical advance warning for applied biosecurity management and planning and demonstrate the importance and utility of extensive multi-species tracking to highlight potential high-risk disease spread locations and more effectively manage outbreaks.

Transboundary and Emerging Diseases↗
USGS2009

Effects of avian cholera on survival of Lesser Snow geese Anser caerulescens: An experimental approach

Avian cholera, caused by the bacterium Pasteurella multocida , is one of the most important diseases affecting waterfowl in North America but little is known about the epizootiology of this disease or its impacts on annual survival rates. We ringed Lesser Snow Geese Anser caerulescens nesting at Wrangel Island, Russia and Banks Island, Canada with metal rings and individually coded plastic neck-collars or radio-transmitters to determine survival, movement and cause of death. We vaccinated half of the neck-collared and radiotagged geese to provide protection from avian cholera for up to one year following ringing and thus experimentally determine the impacts of this disease on survival. We found that vaccination did not reduce short-term survival of the experimental birds, compared with control geese. Neck-collared geese vaccinated in 1993 at Wrangel Island had higher survival during winter 1993–94 than control birds. In contrast, we found similar survival during winter 1994–95 between vaccinated and control geese neck-collared in 1994 at Wrangel and Banks Islands. Survival of radiotagged geese on wintering areas during 1994–95 was consistent with the vaccination versus control results for neck-collared geese during the same winter. However, we found that radiotagged geese that were vaccinated had better survival than control geese during winter 1995–96. We believe that harvest and avian cholera are the two principal causes of mortality for Lesser Snow Geese wintering in the Pacific Flyway and that avian cholera may be one of the factors affecting these populations.

Bird Study↗
USGS2005

Evaluation of current population indices for band-tailed pigeons

There is no formal population survey specifically designed to index population abundance of band-tailed pigeons ( Patagioenas fasciata ) throughout their range. Data from the Breeding Bird Survey (BBS), Washington and Oregon Mineral-Site (WAORMS) surveys, and Washington Call Count (WACC) survey offer evidence of long-term population decline. We investigated the potential to augment BBS, WACC, and WAORMS surveys to provide more precise population indices for the Pacific Coast band-tailed pigeon ( P. f. monilis ) and augment the BBS to index the Interior or “Four Corners” population ( P. f. fasciata ). We calculated statistical power, the probability of detecting population change given that a change exists, and analyzed survey data to investigate the effect of route length, survey repetition, and sample size. Sample sizes of 50 sites or routes yielded corresponding powers of 99% for WAORMS, 54% for WACC, and 30% for Pacific BBS, to detect a 10% annual change over a 5-year period (a = 0.10). Route length and repetition of surveys had little impact on power. Mineral-site surveys provide the greatest potential to monitor breeding populations and detect short-term trends in the Pacific Coast population. New survey techniques are needed for the Interior band-tailed pigeon.

Wildlife Society Bulletin↗
USGS1995

Survival of adult female northern pintails in the Sacramento Valley, California

North American populations of northern pintails (Anas acuta) declined between 1979 and the early 1990s. To determine if low survival during winter contributed to declines, we estimated winter (last week of Aug-Feb 1987-90) survival for 190 adult (after hatching yr [AHY]) female radio-tagged pintails in late summer in Sacramento Valley (SACV), California. Survival rates did not vary by winter ( P = 0.808), among preseason, hunting season, or postseason intervals ( P = 0.579), or by body mass at time of capture ( P = 0.127). Premolt (wing) pintails ( n = 10) tended to survive at a lower rate (0.622, SE = 0.178) than pintails that had already replaced flight feathers (0.887, SE = 0.030) ( P = 0.091). The pooled survival (all years) estimate for the 180-day winter was 0.874 (SE = 0.031). Hunting mortality rate (0.041-0.087) and nonhunting mortality rate (0.013-0.076) did not differ among years ( P = 0.332) or within years (all P > 0.149). Legal hunting ( n = 7), predation ( n = 4), cholera ( n = 2), illegal shooting ( n = 2), botulism ( n = 1), and unknown cause ( n = 1) accounted for all mortality. Nonwintering survival (annu. survival/winter survival = 0.748) was lower than winter survival; thus, if gains in annual survival are desired for this population, managers should first examine the breeding-migration period for opportunities to achieve increases.

California↗