scholarly journals Natality and calf mortality of the Northern Alaska Peninsula and Southern Alaska Peninsula caribou herds

Rangifer ◽  
2003 ◽  
Vol 23 (5) ◽  
pp. 161 ◽  
Author(s):  
Richard A. Sellers ◽  
Patrick Valkenburg ◽  
Ronald C. Squibb ◽  
Bruce W. Dale ◽  
Randall L. Zarnke
Keyword(s):  
Rangifer Tarandus ◽  
Ursus Arctos ◽  
Haliaeetus Leucocephalus ◽  
Bald Eagles ◽  
Alaska Peninsula ◽  
Golden Eagles ◽  
Calf Mortality ◽  
Northern Alaska ◽  
Old Females ◽  
Annual Mortality

We studied natality in the Northern Alaska Peninsula (NAP) and Southern Alaska Peninsula (SAP) caribou (Rangifer tarandus granti) herds during 1996-1999, and mortality and weights of calves during 1998 and 1999- Natality was lower in the NAP than the SAP primarily because most 3-year-old females did not produce calves in the NAP Patterns of calf mortality in the NAP and SAP differed from those in Interior Alaska primarily because neonatal (i.e., during the first 2 weeks of life) mortality was relatively low, but mortality continued to be significant through August in both herds, and aggregate annual mortality was extreme (86%) in the NAP Predators probably killed more neonatal calves in the SAP, primarily because a wolf den (Canis lupus) was located on the calving area. Despite the relatively high density of brown bears (Ursus arctos) and bald eagles (Haliaeetus leucocephalus), these predators killed surprisingly few calves. Golden eagles (Aquila chrysaetos) were uncommon on the Alaska Peninsula. At least 2 calves apparently died from pneu¬monia in the range of the NAP but none were suspected to have died from disease in the range of the SAP. Heavy scav¬enging by bald eagles complicated determining cause of death of calves in both the NAP and SAP.

scholarly journals Calf mortality of semi-domesticated reindeer (Rangifer tarandus tarandus) in the Finnish reindeer-herding area

Rangifer ◽  
2013 ◽  
pp. 79-90 ◽  
Author(s):  
Mauri Nieminen ◽  
Harri Norberg ◽  
Veikko Maijala
Keyword(s):  
Birth Weight ◽  
Rangifer Tarandus ◽  
Total Mortality ◽  
Reindeer Herding ◽  
Brown Bears ◽  
Rangifer Tarandus Tarandus ◽  
Golden Eagles ◽  
Calf Mortality ◽  
Annual Mortality

During 1999-2008 calf mortality was studied in six reindeer-herding cooperatives in Northern Finland, where 3942 semi-domesticated reindeer (Rangifer tarandus tarandus) calves were equipped with radio mortality collars. The calves were weighed and earmarked mostly at 2-5 days of age, or at 2-8 weeks of age. Altogether 460 dead radio-collared calves were found from calving in May until winter round-ups in October-January. In northern mountain herding cooperatives, the average mortality of calves varied between 7-12%. On average, 39-54% of calves found dead were attributed to predation. Golden eagles killed 0-3.5% of calves in different years and areas in Ivalo and Käsivarsi cooperatives. Golden eagles were responsible for 33-43% of the cases and 84-93% of all identified predation. Most calves killed by golden eagles were found in July-August and in open areas. Calves killed by golden eagles were significantly (P<0.01) lighter than those not predated. No predation occurred in the Poikajärvi cooperative, but the annual mortality of calves varied between 0-35% in cooperatives near the Russian border. In Oivanki cooperative brown bears killed on average 2% of the radio-collared calves. Most predation (87%) occurred at the end of May and in early June. In the Kallioluoma cooperative, predator-killed calves found comprised 53% and wolf-killed 45%. Predation was 70% of total mortality in the Halla cooperative, and predation by wolf, bear, lynx and wolverine comprised on average 38%, 20%, 9% and 2.3%, respectively. The sex and pelt color did not significantly affect survival of calves. Birth weight of calves killed by bears was significantly (P<0.01) lighter than those not killed, but those calves killed by lynxes were significantly (P<0.05) heavier than that survived. Bears killed calves mainly in May-July, wolves in July-October and lynx in August-December.

The auditory attributes of Golden Eagles: Do Golden (Aquila chrysaetos) and Bald Eagles (Haliaeetus leucocephalus) share the same auditory space?

2018 ◽  
Vol 144 (3) ◽  
pp. 1742-1742
Author(s):  
Edward J. Walsh ◽  
Peggy B. Nelson ◽  
Julia Ponder ◽  
Christopher Milliren ◽  
Christopher Feist ◽  
...  
Keyword(s):  
Haliaeetus Leucocephalus ◽  
Aquila Chrysaetos ◽  
Bald Eagles ◽  
Auditory Space ◽  
Golden Eagles

Identifying Bald Versus Golden Eagle Bones: A Primer for Wildlife Biologists and Law Enforcement Officers

2017 ◽  
Vol 8 (2) ◽  
pp. 596-610 ◽  
Author(s):  
Pepper W. Trail
Keyword(s):  
Law Enforcement ◽  
Law Enforcement Officers ◽  
High Accuracy ◽  
Skeletal Remains ◽  
Power Lines ◽  
Haliaeetus Leucocephalus ◽  
Wildlife Crime ◽  
Bald Eagles ◽  
Golden Eagles ◽  
Osteological Characters

Abstract Remains of bald eagles Haliaeetus leucocephalus and golden eagles Aquila chrysaetos are regularly encountered in avian mortality surveys and wildlife crime investigations. These species exhibit well-documented plumage differences, allowing identification in most instances when feathers are present. However, skeletal remains are much more difficult to identify and may be the only material available after mortality events (e.g., decomposed remains associated with power lines or wind turbines). Eagle bones are also sometimes incorporated into crafted items without other associated remains. I describe and illustrate shape-based osteological characters that have been determined to be reliable for distinguishing most major bones of bald versus golden eagles. Using the annotated photographs provided as a guide, nonspecialists will be able to identify eagle skeletal remains with high accuracy. This information will be of interest to wildlife law enforcement officers; state, federal, and tribal wildlife biologists documenting avian mortality; and anthropologists and archaeologists.

scholarly journals Wolf predation in the Burwash caribou herd, southwest Yukon

Rangifer ◽  
1986 ◽  
Vol 6 (2) ◽  
pp. 137 ◽  
Author(s):  
David A. Gauthier ◽  
John B. Theberge
Keyword(s):  
Rangifer Tarandus ◽  
Climatic Factors ◽  
Mortality Factor ◽  
Rangifer Tarandus Caribou ◽  
Limited Data ◽  
Mortality Factors ◽  
Wolf Predation ◽  
Calf Mortality ◽  
Annual Mortality

The role of wolf predation as a proximate mortality factor influencing caribou herd growth was assessed in the Burwash herd (400 animals) in the southwest Yukon between 1980 - 1982. Ten to 14 wolves in two packs preyed primarily on caribou (Rangifer tarandus caribou) and moose (Alces alces) with disproportionate consumption of caribou (relative to available biomass) in the rut and winter periods. Wolf predation was responsible for 72% of total annual mortality in 1980 - 1981 and 46% in 1981 - 1982. Losses due to human harvest varied between 7 to 13%. Additional limited data on climatic factors and winter forage indicated forage-climate were not major proximate mortality factors in 1980 - 1981, but that early-calving climate may have been a factor in increased calf mortality in 1982.

scholarly journals Anticoagulant rodenticide exposure and toxicosis in bald eagles (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) in the United States

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0246134
Author(s):  
Kevin D. Niedringhaus ◽  
Nicole M. Nemeth ◽  
Samantha Gibbs ◽  
Jared Zimmerman ◽  
Lisa Shender ◽  
...  
Keyword(s):  
The United States ◽  
Haliaeetus Leucocephalus ◽  
Population Declines ◽  
Anticoagulant Rodenticide ◽  
Aquila Chrysaetos ◽  
Bald Eagles ◽  
University Of Georgia ◽  
Golden Eagles ◽  
The Usa ◽  
Disease Study

Raptors, including eagles, are geographically widespread and sit atop the food chain, thereby serving an important role in maintaining ecosystem balance. After facing population declines associated with exposure to organochlorine insecticides such as dichlorodiphenyltrichloroethane (DDT), bald eagles (Haliaeetus leucocephalus) have recovered from the brink of extinction. However, both bald and golden eagles (Aquila chrysaetos) are exposed to a variety of other toxic compounds in the environment that could have population impacts. Few studies have focused on anticoagulant rodenticide (AR) exposure in eagles. Therefore, the purpose of this study was to determine the types of ARs that eagles are exposed to in the USA and better define the extent of toxicosis (i.e., fatal illness due to compound exposure). Diagnostic case records from bald and golden eagles submitted to the Southeastern Cooperative Wildlife Disease Study (University of Georgia) 2014 through 2018 were reviewed. Overall, 303 eagles were examined, and the livers from 116 bald eagles and 17 golden eagles were tested for ARs. The percentage of AR exposure (i.e., detectable levels but not associated with mortality) in eagles was high; ARs were detected in 109 (82%) eagles, including 96 (83%) bald eagles and 13 (77%) golden eagles. Anticoagulant rodenticide toxicosis was determined to be the cause of mortality in 12 (4%) of the 303 eagles examined, including 11 bald eagles and 1 golden eagle. Six different AR compounds were detected in these eagles, with brodifacoum and bromadiolone most frequently detected (81% and 25% of eagles tested, respectively). These results suggest that some ARs, most notably brodifacoum, are widespread in the environment and are commonly consumed by eagles. This highlights the need for research to understand the pathways of AR exposure in eagles, which may help inform policy and regulatory actions to mitigate AR exposure risk.

scholarly journals Population dynamics of caribou herds in southwestern Alaska

Rangifer ◽  
2003 ◽  
Vol 23 (5) ◽  
pp. 131 ◽  
Author(s):  
Patrick Valkenburg ◽  
Richard A. Sellers ◽  
Ronald C. Squibb ◽  
James D. Woolington ◽  
Andrew R. Aderman ◽  
...  
Keyword(s):  
Rangifer Tarandus ◽  
Management Plan ◽  
Population Declines ◽  
Red Foxes ◽  
Alaska Peninsula ◽  
Naturally Occurring ◽  
Northern Alaska ◽  
Significant Mortality ◽  
Southwestern Alaska

The five naturally occurring and one transplanted caribou (Rangifer tarandus granti) herd in southwestern Alaska composed about 20% of Alaska's caribou population in 2001. All five of the naturally occurring herds fluctuated considerably in size between the late 1800s and 2001 and for some herds the data provide an indication of long-term periodic (40-50 year) fluctuations. At the present time, the Unimak (UCH) and Southern Alaska Peninsula (SAP) are recovering from population declines, the Northern Alaska Peninsula Herd (NAP) appears to be nearing the end of a protracted decline, and the Mulchatna Herd (MCH) appears to now be declining after 20 years of rapid growth. The remaining naturally occurring herd (Kilbuck) has virtually disappeared. Nutrition had a significant effect on the size of 4-month-old and 10-month-old calves in the NAP and the Nushagak Peninsula Herd (NPCH) and probably also on population growth in at least 4 (SAP, NAP, NPCH, and MCH) of the six caribou herds in southwestern Alaska. Predation does not appear to be sufficient to keep caribou herds in southwestern Alaska from expanding, probably because rabies is endemic in red foxes (Vulpes vulpes) and is periodically transferred to wolves (Canis lupus) and other canids. However, we found evidence that pneumonia and hoof rot may result in significant mortality of caribou in southwestern Alaska, whereas there is no evidence that disease is important in the dynamics of Interior herds. Cooperative conservation programs, such as the Kilbuck Caribou Management Plan, can be successful in restraining traditional harvest and promoting growth in caribou herds. In southwestern Alaska we also found evidence that small caribou herds can be swamped and assimilated by large herds, and fidelity to traditional calving areas can be lost.

scholarly journals Ecological interactions and habitat modification in nesting Common Murres, Uria aalge

1996 ◽  
Vol 6 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Julia K. Parrish ◽  
Robert T. Paine
Keyword(s):  
Reproductive Output ◽  
Habitat Modification ◽  
Haliaeetus Leucocephalus ◽  
Uria Aalge ◽  
Ecological Interactions ◽  
Bald Eagles ◽  
Predator Removal ◽  
Common Murre ◽  
Corvus Caurinus ◽  
Common Murres

SummarySeabird populations suffer from a variety of natural and human-induced sources of mortality and loss of lifetime reproductive output. On the outer coast of Washington State, Common Murre Uria aalge populations have been in decline for approximately the last decade and are currently reproductively active only at Tatoosh Island. These murres nest in two basic habitat types: crevices (25% of the population) and larger cliff-top subcolonies (75%). Murres in cliff-top subcolonies have suffered dramatic reductions in reproductive success in recent years relative to conspecifics nesting in the crevices, primarily due to egg predation by Glaucous-winged Gulls Larus glaucescens and Northwestern Crows Corvus caurinus, facilitated by the presence of Bald Eagles Haliaeetus leucocephalus. Because predator removal is not feasible and creation of additional crevice habitat is difficult, expensive and potentially ineffective, we have designed a temporary habitat modification (the “silk forest”) which replaces the natural vegetation cover and modifies the interaction between murres and eagles. Within the test subcolony, murres nesting under and immediately adjacent to the silk forest produced nearly twice as many eggs per square metre as their conspecifics nesting in adjacent exposed-ground areas.

Displacement and dispersion of parturient caribou at calving as antipredator tactics

1987 ◽  
Vol 65 (7) ◽  
pp. 1597-1606 ◽  
Author(s):  
A. T. Bergerud ◽  
R. E. Page
Keyword(s):  
Snow Cover ◽  
Rangifer Tarandus ◽  
Forest Cover ◽  
Ursus Arctos ◽  
Early Years ◽  
Stochastic Variation ◽  
Spring Phenology ◽  
Calf Survival ◽  
Searching Ability ◽  
High Elevations

Survival of caribou (Rangifer tarandus) calves until 4 months of age was monitored for 8 years in four herds in northern British Columbia, Canada. The chief cause of mortality was predation by wolves (Canis lupus) and grizzly bears (Ursus arctos) and this mortality was correlated within years between all herds. More calves died in years with late springs when extensive snow patches remained during calving in June than in early springs when larger snow-free areas existed. Before calving and after birth, caribou cows sought to space themselves out on snow-free areas in small aggregations at high elevations above treeline. By placing themselves at high elevations, the females increased the distance between themselves and wolves and bears travelling in the valley bottoms, as well as the main alternate prey, moose (Alces alces), which calved only in forest cover at lower elevations. In addition, the reduced snow in early springs meant that there was more space for dispersion. The variation in calf survival for three herds was negatively correlated with the heterogeneity of the calving area. Snow cover disappeared in smaller patches in more rugged mountains regardless of spring phenology, thereby providing a more constant search area for predators from year to year. More uniform mountains had either extensive areas of snow cover (late years) or brown substrates (early years), thus greatly varying the space that predators had to search between years. As stochastic variation in snow cover at calving time alters the searching ability of predators, the aggregation responses of prey, and the spatial overlap between predators and prey, it promotes short-term stability of the prey and lessens the probability of extinction.

scholarly journals The impact of large carnivores on the mortality of semi-domesticated reindeer (Rangifer tarandus tarandus L.) calves in Kainuu, southeastern reindeer-herding region of Finland

Rangifer ◽  
2010 ◽  
Vol 30 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Mauri Nieminen
Keyword(s):  
Birth Weight ◽  
Rangifer Tarandus ◽  
Annual Variation ◽  
Total Mortality ◽  
Large Carnivores ◽  
Reindeer Herding ◽  
Eurasian Lynx ◽  
Causes Of Mortality ◽  
Calf Mortality ◽  
The Impact

During 2006-2008 the survival of reindeer calves was studied in the reindeer-herding cooperative of Halla in Kainuu area where totally 546 calves were equipped with radio mortality collars mainly at the age of 1-3 days. The survival was monitored from the calving in May until winter round-ups in October to January. The rate, timing and causes of mortality of reindeer were assessed. In 2006-08 totally 177 radio-collared calves were found dead (mean mortality 32.4%) until mid-January. The results showed significant annual variation in calf mortality and predation. Independent of year the mortality of radio-collared calves was highest during the first two months after birth, and the total mortality was 30.7% at the end of October and reached 34.6% by mid-January. The sex of calves and pelt colour did not affect significantly survival of calves. Predation comprised 70.0% of total mortality. Predation by wolf, bear, lynx and wolverine comprised on average 38.4%, 20.3%, 9.0% and 2.3%, respectively. Birth weight of calves lost or killed by predators did not differ from surviving calves. However, birth weight of calves killed by brown bears was significantly lighter (mean 5.84 kg), whereas calves killed by Eurasian lynx was significantly heavier (mean 6.67 kg) than birth weight of calves that survived (mean 6.26 kg). Bears killed calves mainly in May to July, wolves in July to October and lynx in August to December. Of 209 radio-collared adult females, 17 were found dead (8.0%). These females had calved in May and they were killed mainly by wolves (52.0%) in August to October.

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