Flying the Gantlet: Population Characteristics, Sampling Bias, and Migration Routes of Eared Grebes Downed in the Utah Desert

Jehl, Joseph R.; Henry, Allison; Bond, Suzanne I.

doi:10.2307/4089464

Cited by 25 publications

(7 citation statements)

References 5 publications

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“…Our results indicate that interactions with commercial harvesters of brine shrimp cysts do not negatively impact Eared Grebe abundances on the GSL. Jehl et al (1999) argued that Mono Lake hosts more Eared Grebes because of a safer migration corridor, but our data suggest that more birds have used the GSL in recent years, despite constant brine shrimp cyst harvest. In addition, our data further support population regulation of Eared Grebes at wintering areas or breeding areas, rather than at the GSL or Mono Lake during the fall-staging period.…”

Section: Densities Of Eared Grebes (Podicepsmentioning

confidence: 52%

Population fluctuations and distribution of staging Eared Grebes (Podiceps nigricollis) in North America

Roberts

Conover

Luft³

et al. 2013

Can. J. Zool.

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Eared Grebes (Podiceps nigricollis Brehm, 1831) use saline ecosystems throughout much of their life cycle, and greater than 90% of the North American population stage during fall at two hypersaline lakes. At one of these lakes, Great Salt Lake (GSL), Utah, a commercial harvest of brine shrimp (Artemia franciscana Kellogg, 1906) cysts occurs during fall and may impact Eared Grebe populations. We used photo surveys on the other hypersaline lake, Mono Lake, California, and on the GSL, as well as aerial counts on the GSL, to describe population fluctuations of Eared Grebes staging on these lakes. The long-term (1997-2012) Eared Grebe population was 1.4 million on the GSL and 1.0 million on Mono Lake. Populations changed on GSL and Mono Lake in synchrony, indicating population regulation is likely occurring at wintering, not staging, areas and is influenced by El Niño effects. Location of Eared Grebes on the GSL was influenced by brine shrimp densities and did not overlap with concentrations of commercial harvest boats. Spatial segregation of commercial harvesters and Eared Grebes reduces negative impacts of anthropogenic disturbance on Eared Grebes. Knowledge of population changes within and among staging areas will help managers monitor long-term abundances and reduce negative impacts between Eared Grebes and commercial harvesters. Résumé : Les grèbes à cou noir (Podiceps nigricollis Brehm, 1831) utilisent des écosystèmes salins pendant une bonne partie de leur cycle biologique, et plus de 90 % de la population nord-américaine utilise deux lacs hypersalins comme haltes migratoires à l'automne. À l'un de ces deux lacs, le Grand Lac salé (Utah; GSL), une récolte à des fins commerciales de kystes d'artémia (Artemia franciscana Kellogg, 1906) a lieu à l'automne et pourrait avoir un impact sur les populations de grèbes à cou noir. Nous avons utilisé des levés photographiques sur l'autre lac hypersalin, le lac Mono (Californie), et sur le GSL, et des décomptes aériens sur le GSL pour décrire les fluctuations des populations de grèbes à cou noir en halte migratoire à ces lacs. Les populations à long terme (1997-2012) de grèbes à cou noir étaient de 1,4 million et 1,0 million d'individus, respectivement, sur le GSL et le lac Mono. Les variations des populations sur le GSL et sur le lac Mono sont synchrones, ce qui indique que la régulation des populations s'opère vraisemblablement dans les aires d'hivernage plutôt qu'aux haltes migratoires, et qu'elle est influencée par les effets d'El Niño. La répartition des grèbes à cou noir sur le GSL était influencée par les densités d'artémias et ne recoupait pas les concentrations de bateaux s'adonnant à l'exploitation commerciale d'artémia. La ségrégation spatiale des exploitants et des grèbes à cou noir limite les impacts négatifs des perturbations humaines sur ces oiseaux. La connaissance des variations des populations dans les haltes migratoires et entre elles aidera les aménageurs à surveiller l'abondance à long terme des grèbes à cou noir et à réduire les impacts négatifs de l...

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Section: Densities Of Eared Grebes (Podicepsmentioning

confidence: 52%

Population fluctuations and distribution of staging Eared Grebes (Podiceps nigricollis) in North America

Roberts

Conover

Luft³

et al. 2013

Can. J. Zool.

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“…After one such event in December 1928, most were dead, having struck trees or buildings, but others were busy working themselves out of the snow (Cottam 1929). In January 1997, bad weather in southern Utah several times brought grebes to ground, an estimated total of 35 000, forming about 3% of the population that stages at the Great Salt Lake (Jehl et al . 1999).…”

Section: Resultsmentioning

confidence: 99%

Weather‐related mass‐mortality events in migrants

Newton¹

2007

Ibis

268

255

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A major perceived cost of migration in birds is the associated mortality. This mortality has proved difficult to measure and separate from mortality during stationary periods of the annual cycle. This paper reviews some major recorded mortality incidents among migratory birds attributed to inclement weather and other factors, including: (1) in-flight losses, caused by storms and other adverse weather en route, usually over water; (2) unseasonable cold weather soon after arrival in breeding areas; and (3) unseasonable cold weather before departure from breeding areas. Cold weather often kills migrants in their breeding areas, but not the local resident species which can better withstand it at those times. For migrants, cold and snow act to cut off the food supply, and can have a major selective effect on the seasonal timing of migration. Records of in-flight weather-induced mortality, involving up to hundreds or thousands of birds at a time, have affected mainly small passerines, but also larger birds, including eagles and swans. Most occurred in conditions of mist, rain or snow storms, and some involved nocturnal collisions with illuminated masts and other tall structures. Records of post-arrival mortality in breeding areas have involved mainly small insectivores (especially hirundines), but also waders and waterfowl. Such incidents, associated with cold and snow, have reduced local breeding densities from the previous year by 25-90%, depending on species and area, with up to several years required for recovery. Records of pre-departure mortality on breeding areas have mainly affected hirundines. Two major incidents in central Europe in September 1931 and 1974 killed hundreds of thousands, or even millions, of swallows and martins. After the latter incident, House Martin Delichon urbicum populations in Switzerland the following year were reduced by an estimated 25-30%. Such climatic extremes that occurred in spring or late summer in particular parts of the breeding range have been recorded at approximate mean frequencies of 2-10 per century. Average daily mortality in many bird species can clearly be much greater during migration periods than during stationary periods. Despite the heavy losses of birds on migration, it may be assumed that migration persists in the long term because the fitness costs (in terms of associated mortality) are more than offset by the fitness benefits (in terms of improved overall survival and breeding success) that accrue from migration.

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“…The majority of Great Salt Lake isolates analyzed for this study were cultured from Eared Grebes, while Salton Sea isolates were primarily cultured from Eared Grebes and Ruddy Ducks (Table 1). Large numbers of Eared Grebes move between the Great Salt Lake and the Salton Sea each year (Jehl, 1993;Jehl et al, 1999). Thus, interactions between Great Salt Lake and Salton Sea Eared Grebe populations may facilitate the transmission of disease agents between these two sites resulting in genetic homogenization, as measured by AFLP analysis, of the P. multocida isolates cultured from waterfowl of this geographic region.…”

Section: Discussionmentioning

confidence: 99%

Using Amplified Fragment Length Polymorphism Analysis to Differentiate Isolates of Pasteurella Multocida Serotype 1

Blehert

Jefferson

Heisey

et al. 2008

Journal of Wildlife Diseases

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ABSTRACT:Avian cholera, an infectious disease caused by the bacterium Pasteurella multocida, kills thousands of North American wild waterfowl annually. Pasteurella multocida serotype 1 isolates cultured during a laboratory challenge study of Mallards (Anas platyrhynchos) and collected from wild birds and environmental samples during avian cholera outbreaks were characterized using amplified fragment length polymorphism (AFLP) analysis, a whole-genome DNA fingerprinting technique. Comparison of the AFLP profiles of 53 isolates from the laboratory challenge demonstrated that P. multocida underwent genetic changes during a 3-mo period. Analysis of 120 P. multocida serotype 1 isolates collected from wild birds and environmental samples revealed that isolates were distinguishable from one another based on regional and temporal genetic characteristics. Thus, AFLP analysis had the ability to distinguish P. multocida isolates of the same serotype by detecting spatiotemporal genetic changes and provides a tool to advance the study of avian cholera epidemiology. Further application of AFLP technology to the examination of wild bird avian cholera outbreaks may facilitate more effective management of this disease by providing the potential to investigate correlations between virulence and P. multocida genotypes, to identify affiliations between bird species and bacterial genotypes, and to elucidate the role of specific bird species in disease transmission.

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Flying the Gantlet: Population Characteristics, Sampling Bias, and Migration Routes of Eared Grebes Downed in the Utah Desert

Cited by 25 publications

References 5 publications

Population fluctuations and distribution of staging Eared Grebes (Podiceps nigricollis) in North America

Population fluctuations and distribution of staging Eared Grebes (Podiceps nigricollis) in North America

Weather‐related mass‐mortality events in migrants

Using Amplified Fragment Length Polymorphism Analysis to Differentiate Isolates of Pasteurella Multocida Serotype 1

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