scholarly journals Calving photocensus of the Rivière George Caribou Herd and comparison with an independent census

Rangifer ◽  
1996 ◽  
Vol 16 (4) ◽  
pp. 283 ◽  
Author(s):  
Serge Couturier ◽  
Réhaume Courtois ◽  
Hélène Crépeau ◽  
Louis-Paul Rivest ◽  
Stuart Luttich
Keyword(s):  
Rangifer Tarandus ◽  
Sampling Design ◽  
Herd Size ◽  
Population Estimates ◽  
Female Adult ◽  
The World ◽  
Calf Survival ◽  
Valid Estimate ◽  
Sampling Problems ◽  
Size Estimates

Vertical photographs of the calving grounds have been used since 1984 to estimate the caribou (Rangifer tarandus) population of the Rivière George Caribou Herd (RGCH) in Northern Québec and Labrador. In spite of large confidence intervals, the 1984 and 1988 estimates suggested that the herd stabilized at more than 650 000 caribou (fall estimate including calves) making the RGCH the largest caribou herd in the world. Between 1984 and 1990, studies suggested that the former rapid growth of the herd deteriorated the calving and summer habitats. This poor habitat quality affected physical condition, pregnancy rate and calf survival. It was important to have a valid estimate of the herd size and a photocensus was done in June 1993. Contrary to previous censuses, a slightly different sampling design was applied in 1993. Two methods were used to estimate the number of females in the June population. In the first method, the number of females was derived from the estimated number of calves on the photographs and from the June female/calf ratio. The second method was used in the previous census and is based on the number of adults on the photos and on the June female/adult ratio. It is suggested that the first method of estimating female abundance in June is better due to sampling problems associated with a strong adult sex segregation during calving. From the first method, the herd size in October 1993 was estimated at 583 829 adults (±33.79%) and at 749 869 caribou including calves (±33.15%) while the second method provided estimates of 764 221 adults (±23.55%) and 981 565 caribou including calves (±22.64%). It was possible to compare those population estimates with an independent census. In July 1993, an oblique photocensus of the post-calving aggregations was conducted by Russell et al. (1996). A new analysis of their raw data provided an estimate of 608 384 adults (±14.35%). Both estimates from the June and July photocensus were combined. From the first and second method respectively, combined herd size estimates were 775 891 (±13.40%) and 823 375 (±12.36%) caribou including calves. The management implications are discussed and it is emphasized that the herd is still underharvested.

scholarly journals World status of wild Rangifer tarandus populations

Rangifer ◽  
1986 ◽  
Vol 6 (2) ◽  
pp. 19 ◽  
Author(s):  
T. Mark Williams ◽  
Douglas C. Heard
Keyword(s):  
North America ◽  
North American ◽  
Aerial Photography ◽  
Rangifer Tarandus ◽  
Population Estimates ◽  
World Population ◽  
South Georgia ◽  
The World ◽  
Strip Transect

We recognized 184 herds of wild Rangifer tarandus, 102 in North America, 55 in Europe, 24 in Asia and 3 on South Georgia. Seventy-five percent of the world population of 3.3 to 3.9 million animals occurred in nine herds. All seven herds larger than 120 000 animals were censused by some means of aerial photography and all were increasing. Herds between 20 000 and 120 000 were most often censused using aerial strip transect methods, while total counts were usually employed to census smaller herds. The most pronounced changes in Rangifer herd status between 1979 and 1985 occurred in North America where population "estimates for five herds increased by a total of about one million animals. Part of this increase is attributable to a change from visual to photographic surveys. Eighty-three percent of North American, 88% of European, and 68% of Asian herds were stable or increasing.

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 Case history of the Fortymile Caribou Herd, 1920-1990

Rangifer ◽  
1994 ◽  
Vol 14 (1) ◽  
pp. 11 ◽  
Author(s):  
Patrick Valkenburg ◽  
David G. Kelleyhouse ◽  
James L. Davis ◽  
Jay M. Ver Hoef
Keyword(s):  
Case History ◽  
Historical Data ◽  
Herd Size ◽  
Limiting Factors ◽  
Winter Weather ◽  
Winter Conditions ◽  
The World ◽  
History Of ◽  
Alternate Prey

Early this century, the Fortymile caribou herd was the largest in Alaska and one of the largest in the world. Since the 1940s the herd has remained relatively small, fluctuating between 6000-8000 and about 50 000. To determine possible limiting factors, we reviewed historical fluctuations in herd since and harvest, historical data on wolf numbers and summer and winter weather. The major decline in herd size from 1963 to 1973 was accompanied by high wolf numbers, some years of unfavorable winter and summer weather, and some years of high harvests. From 1974 to 1990 the Fortymile herd failed to recover as well as the adjacent Nelchi-na herd and provided less than one-fourth the harvest despite favorable winter conditions in both areas. Two notable differences between these herds were that (1) wolves were less strongly limited within the range of the Fortymile herd, and (2) moose as alternate prey for wolves remained more abundant within the range of the Nelchina herd.

scholarly journals A Comparative Proteomic Analysis of Praziquantel-Susceptible and Praziquantel-Resistant Schistosoma mansoni Reveals Distinct Response Between Male and Female Animals

2021 ◽  
Vol 2 ◽  
Author(s):  
António Pinto-Almeida ◽  
Tiago M. F. Mendes ◽  
Pedro Ferreira ◽  
Ana B. Abecasis ◽  
Silvana Belo ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Schistosoma Mansoni ◽  
Rural Areas ◽  
Neglected Tropical Disease ◽  
Female Adult ◽  
Male And Female ◽  
Comparative Proteomic Analysis ◽  
The World ◽  
And Control

Schistosomiasis is a chronic neglected tropical disease saddling millions of people in the world, mainly children living in poor rural areas. Praziquantel (PZQ) is currently the only drug used for the treatment and control of this disease. However, the extensive use of this drug has brought concern about the emergence of PZQ-resistance/tolerance by Schistosoma mansoni. Studies of Schistosoma spp. genome, transcriptome, and proteome are crucial to better understand this situation. In this in vitro study, we compare the proteomes of a S. mansoni variant strain stably resistant to PZQ and isogenic to its fully susceptible parental counterpart, identifying proteins from male and female adult parasites of PZQ-resistant and PZQ-susceptible strains, exposed and not exposed to PZQ. A total of 60 Schistosoma spp. proteins were identified, some of which present or absent in either strain, which may putatively be involved in the PZQ-resistance phenomenon. These proteins were present in adult parasites not exposed to PZQ, but some of them disappeared when these adult parasites were exposed to the drug. Understanding the development of PZQ-resistance in S. mansoni is crucial to prolong the efficacy of the current drug and develop markers for monitoring the potential emergence of drug resistance.

scholarly journals Body size of female calves and natality rates of known-aged females in two adjacent Alaskan caribou herds, and implications for management

Rangifer ◽  
2003 ◽  
Vol 23 (5) ◽  
pp. 203 ◽  
Author(s):  
Patrick Valkenburg ◽  
Robert W. Tobey ◽  
Robert W. Tobey ◽  
Bruce W. Dale ◽  
Bruce W. Dale ◽  
...  
Keyword(s):  
Body Size ◽  
Population Growth ◽  
Body Mass ◽  
Real Option ◽  
Rangifer Tarandus ◽  
Herd Size ◽  
Adult Females ◽  
Potential Population ◽  
Newborn Calves ◽  
Natality Rate

We studied body mass of female calves and natality rate of adult females in two adjacent Interior Alaskan caribou (Rangifer tarandus granti) herds during 1991-2001. Mass of newborn calves was similar in both herds, but Delta calves gained significantly more mass over summer than Nelchina calves. In contrast, Nelchina calves consistently maintained their mass during winter while Delta calves lost mass. Metatarsus length was similar in both herds in 4-month-old and 10-month-old calves, and it increased over winter in both herds. Natality rates of females >3 years old were consistently higher in the Delta Herd than in the Nelchina Herd, primarily because natality in 3- to 5-year-old Nelchina females was low. Although body mass of Delta Herd calves consistently declined over winter, we concluded that nutrition was not significantly limiting herd growth. Managers are more likely to maximize harvest by maintaining the Delta Herd near its present size (i.e., 3500), or allowing it to increase only slightly. The only real option for increasing harvestable surpluses of caribou in the Delta Herd is reducing predation during calving and summer. In contrast, we conclude that summer nutrition significantly limits potential population growth and body mass in the Nelchina Herd, and managers are more likely to maximize harvest by maintaining herd size at or below 30 000 than by allowing the herd to grow to near historical highs (i.e., 60 000-70 000).

scholarly journals Calving distribution of Alaska's Steese-Fortymile caribou herd: A case of infidelity?

Rangifer ◽  
1986 ◽  
Vol 6 (2) ◽  
pp. 315 ◽  
Author(s):  
Patrick Valkenburg ◽  
James L. Davis
Keyword(s):  
Rangifer Tarandus ◽  
Herd Size ◽  
The Past ◽  
Predator Abundance

The Steese-Fortymile caribou (Rangifer tarandus granti) herd has changed its calving distribution frequently during the past 30 years. A «traditional» calving area, used for decades, west of the Steese Highway (Preacher Creek) was abandoned after 1963. By the early 1970's, a new calving area had been established 74 km to the southeast in the Birch Creek drainage. This new calving area was abandoned after 1976. From 1977 through 1983, calving occurred in annually variable locations approximately 136 km southeast of the Birch Creek calving area. In 1984, however, the herd again calved in the general vicinity of the Birch Creek calving area. General characteristics of the various calving areas are described, and calving distribution is discussed in relation to herd size, development and disturbance, predator abundance, and other factors. Location of calving in recent years was unpredictable, which warrants reconsidering the merit of protecting only previously important calving grounds.

scholarly journals The Sundrun population of wild reindeer

Rangifer ◽  
2003 ◽  
Vol 23 (5) ◽  
pp. 193
Author(s):  
Ivan Sivtsev
Keyword(s):  
Population Dynamics ◽  
Sex Ratio ◽  
Rangifer Tarandus ◽  
Population Estimates ◽  
Seasonal Migrations ◽  
Wintering Areas ◽  
The 1950S ◽  
Wild Reindeer ◽  
Separate Population

The Sundrun wild reindeer (Rangifer tarandus) herd was recognized as a separate population during the 1950s. Since then, the herd has ranged over an area of approximately 180 000 km2 between the Indigirka and Kolyma Rivers in northeastern Yakutia. Population dynamics and movements were investigated between 1987 and 1997. During this period, the population estimates ranged from 25 000 to 45 000 reindeer, the sex ratio averaged 55 bulls:100 cows, and the percentage of calves in the herd ranged between 17% and 25%. The main routes of seasonal migrations, wintering areas, and the location of calving areas are discussed.

Estimation of seabird bycatch for North Pacific longline vessels using design- and model-based methods

2006 ◽  
Vol 63 (8) ◽  
pp. 1878-1889 ◽  
Author(s):  
T J Miller ◽  
J R Skalski
Keyword(s):  
North Pacific ◽  
Sampling Design ◽  
Sensitive Species ◽  
Seabird Species ◽  
Probability Sampling ◽  
Complex Sampling ◽  
The North ◽  
The World ◽  
Complex Sampling Design ◽  
The North Pacific

Bycatch estimation for sensitive species is becoming increasingly important with the shift toward an ecosystem-based approach to fisheries management. Incidental mortalities for various seabird species occur on longline vessels throughout the world, including those in the North Pacific groundfish fleet. We present an approach to seabird bycatch estimation for North Pacific longline vessels using observer-collected data. Observers collect enormous amounts of data through a complex sampling design, but some information deficiencies preclude bycatch estimation using only probability sampling. Our approach combines probability sampling with model-dependent techniques to overcome these information deficiencies. The resulting bycatch estimator reflects the observer sampling design as closely as possible and minimizes reliance on untested model assumptions. We apply our estimator to black-footed albatross (Phoebastria nigripes) bycatch as an example and compare yearly estimates to those previously published. We also suggest changes in data collection that would further reduce dependence on model assumptions.

Calving success of female caribou in relation to body weight

1993 ◽  
Vol 71 (3) ◽  
pp. 480-486 ◽  
Author(s):  
Raymond D. Cameron ◽  
Walter T. Smith ◽  
Steven G. Fancy ◽  
Karen L. Gerhart ◽  
Robert G. White
Keyword(s):  
Body Weight ◽  
Reproductive Performance ◽  
Rangifer Tarandus ◽  
Post Partum ◽  
Logistic Models ◽  
Late Pregnancy ◽  
Maternal Condition ◽  
Successful Pregnancy ◽  
Body Weights ◽  
Calf Survival

In late September and October 1987–1990 and early July 1988–1991, 66 radio-collared female caribou (Rangifer tarandus granti) of the Central Arctic Herd were captured and weighed 117 times. Caribou were relocated repeatedly during early June 1988–1991; parturition status, calving date, and perinatal calf survival were determined. Mean autumn body weights of subsequently parturient (90.0 kg) and nonparturient (82.5 kg) females differed significantly (P < 0.01). Mean summer weights 4 – 5 weeks after parturition were significantly higher for females that had calved on or before 7 June (82.2 kg) than for those that had calved after 7 June (72.1 kg; P < 0.01), and for females whose calves survived at least 2 days post partum (80.2 kg) than for those whose calves died within 2 days (70.3 kg; P < 0.01). Significant logistic models were generated for relationships between parturition rate and autumn weight (P < 0.01), between the occurrence of early calving and summer weight (P < 0.05), and between calf survival rate and summer weight (P < 0.02). Body weight appears to be a reasonable index of body condition, which in turn is related to reproductive performance. The probability of a successful pregnancy is largely predetermined at breeding, based on autumn condition, whereas calving date and early calf survival appear to be influenced primarily by maternal condition during late pregnancy.

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