Two caribou mortality events in Northwest Alaska: possible causes and management implications

During fall and winter 1994—1995 and winter 1999—2000, caribou (Rangifer tarandus granti) from the Western Arctic Herd experienced high, localized mortality in northwest Alaska near Cape Thompson. Substantial numbers of caribou wintered in this area during 1986—1987, 2001—2002, and 2002—2003 without suffering high mortality. During the 1994—1995 event, 2000 to 3000 caribou died out of roughly 10 000 that wintered in this area. About 4000 caribou perished out of approximately 20 000 that wintered here during 1999—2000. During both mortality events, gross characteristics and tissue analyses indicated caribou in this area were malnourished. Weather near Cape Thompson during winter 1994—1995 was colder, windier, and had more snow than other years when caribou wintered in this area; in contrast, conditions during 1999—2000 were not unusually severe. Additionally, Cape Thompson experienced 2—5 occurrences of severe conditions during winter 1994—1995 while 1999—2000 experienced only 1 such occurrence at most. Several indicators suggested severe storms killed some caribou before starvation was fatal. Cape Thompson consistently experienced higher wind, lower ambient air temperature, and shallower snow cover than other portions of winter range used by this herd. Unlike years when caribou wintered in this area without experiencing high mortality, caribou were in relatively poor body condition during the autumn that preceded each die-off. Although these mortality events were inconsequential to size of this caribou herd, they raised local residents' concerns that contaminants had poisoned caribou and possibly jeopardized human health. Muskoxen (Ovibos moschatus) in this area were not affected by weather or snow conditions during either caribou mortality event

Two caribou mortality events in Northwest Alaska: possible causes and management implications

During fall and winter 1994—1995 and winter 1999—2000, caribou (Rangifer tarandus granti) from the Western Arctic Herd experienced high, localized mortality in northwest Alaska near Cape Thompson. Substantial numbers of caribou wintered in this area during 1986—1987, 2001—2002, and 2002—2003 without suffering high mortality. During the 1994—1995 event, 2000 to 3000 caribou died out of roughly 10 000 that wintered in this area. About 4000 caribou perished out of approximately 20 000 that wintered here during 1999—2000. During both mortality events, gross characteristics and tissue analyses indicated caribou in this area were malnourished. Weather near Cape Thompson during winter 1994—1995 was colder, windier, and had more snow than other years when caribou wintered in this area; in contrast, conditions during 1999—2000 were not unusually severe. Additionally, Cape Thompson experienced 2—5 occurrences of severe conditions during winter 1994—1995 while 1999—2000 experienced only 1 such occurrence at most. Several indicators suggested severe storms killed some caribou before starvation was fatal. Cape Thompson consistently experienced higher wind, lower ambient air temperature, and shallower snow cover than other portions of winter range used by this herd. Unlike years when caribou wintered in this area without experiencing high mortality, caribou were in relatively poor body condition during the autumn that preceded each die-off. Although these mortality events were inconsequential to size of this caribou herd, they raised local residents' concerns that contaminants had poisoned caribou and possibly jeopardized human health. Muskoxen (Ovibos moschatus) in this area were not affected by weather or snow conditions during either caribou mortality event

Response of Overwintering Caribou to Burned Habitat in Northwest Alaska

Caribou (Rangifer tarandus granti) use lichens, when available, as primary forage on their winter range. In boreal forest habitats, wildland fires effectively destroy lichens, and overwintering caribou are known to avoid burned areas for decades while lichen communities regenerate. However, little has been published about caribou response to burned habitat in tundra ecosystems. To assess the relationship between winter caribou distribution and burned areas, we instrumented Western Arctic Herd caribou with satellite telemetry collars and evaluated their locations in relation to recent burns of known age (? 55 years old) across northwestern Alaska. We analyzed caribou distribution for different habitat types (tundra and boreal forest), age categories of burns, and possible edge effects. We also reanalyzed the data, limiting available habitat to a uniform traveling distance (5658 m) from daily satellite locations. Using selection indices that compared caribou use of burns and buffers to their availability, we found that caribou strongly selected against burned areas within the tundra ecosystem. Recent burns were selected against at both large (range-wide) and intermediate (5658 m) spatial scales. Caribou particularly selected against 26- to 55-year-old burns and the interior (core) portions of all burns. We found that caribou were more likely to select burned areas in the late fall and early spring than midwinter. Increased fires in northwestern Alaska could decrease the availability and quality of winter habitat available to the herd over the short term (up to 55 years), potentially influencing herd population dynamics and reducing sustainable harvest levels. We recommend that fire managers consider caribou midwinter range condition and extent: however, management that achieves a mosaic pattern of fire history may benefit a wide array of species, including caribou. A better understanding of the current regional fire regime and the distribution of available winter range will be required before practicable management recommendations can be developed for this herd.Le fourrage principal du parcours d’hiver du caribou (Rangifer tarandus granti) est le lichen, lorsque celui-ci se trouve à sa disposition. Dans les habitats de forêt boréale, les feux de broussailles détruisent les lichens, au point où les caribous évitent, pendant des décennies l’hiver, les régions qui ont été brûlées afin de laisser le temps au lichen de se régénérer. Cependant, peu d’information a été publiée à l’égard de la réaction du caribou envers l’habitat brûlé des écosystèmes de la toundra. Afin d’évaluer la relation entre la répartition du caribou d’hiver et les régions brûlées, nous avons posé à un troupeau de caribous de l’Arctique de l’Ouest des colliers émetteurs à télémétrie par satellite et évalué leur emplacement par rapport à des régions brûlées récemment dont on savait à quand remontaient les incendies (? 55 ans) et ce, aux quatre coins du nord-ouest de l’Alaska. Nous avons analysé la répartition du caribou en fonction de types d’habitats différents (la toundra et la forêt boréale), de catégories d’âge des régions brûlées et d’effets de lisière possibles. De plus, nous avons réanalysé les données en prenant soin de limiter l’habitat disponible à une distance de déplacement uniforme (5 658 m) à partir des emplacements satellites quotidiens. Grâce aux indices de sélection comparant l’utilisation faite par les caribous des régions brûlées et des zones tampons et leur disponibilité, nous avons remarqué que le caribou délaissait fortement les régions brûlées dans l’écosystème de la toundra. Les régions brûlées récemment étaient rejetées tant à la grande échelle spatiale (l’ensemble du parcours) qu’à l’échelle intermédiaire (5658 m). Plus particulièrement, le caribou se tenait loin des régions brûlées il y a 26 à 55 ans et des sections intérieures (au centre) de toutes les régions brûlées. Nous avons constaté que le caribou était plus susceptible d’opter pour les régions brûlées vers la fin de l’automne et au début du printemps qu’au milieu de l’hiver. Les incendies à la hausse dans le nord-ouest de l’Alaska pourraient avoir pour effet de diminuer la disponibilité et la qualité de l’habitat d’hiver à la disposition du troupeau à court terme (jusqu’à 55 ans), ce qui pourrait influencer la dynamique de la population du troupeau et réduire les taux de récoltes durables. Nous recommandons que les directeurs des incendies considèrent l’état et l’étendue du parcours du caribou en parcours d’hiver. Cela dit, une gestion donnant lieu à un dessin en mosaïque de l’historique des incendies pourrait avantager une vaste gamme d’espèces, dont le caribou. Il faudra avoir une meilleure compréhension du régime régional actuel des incendies et de la répartition du parcours d’hiver disponible avant que des recommandations de gestion réalisables puissent être faites pour ce troupeau

Investigation of Heavy Metals in a Large Mortality Event in Caribou of Northern Alaska

We measured element concentrations (As, Cd, Cu, Pb, Zn, Fe) and body condition (gross and histologic endpoints) of animals from a caribou (Rangifer tarandus) mortality event that occurred in Alaska, in the area of Point Hope and Cape Thompson (including the Chariot site), in 1995. These were compared to results from hunter-killed caribou from reference sites (Barrow and Teshekpuk Lake, Alaska) and from the area of a mine (Red Dog Mine) to determine whether heavy metals had played a role in the mortality event or whether any elements were at concentrations of concern for human consumers. Starvation and malnutrition were major factors leading to death or severe weakness, as very little or no fat (very low body condition scores) and serous atrophy of fat (observed as watery contents of the marrow cavity, with no apparent fat, and histologically) were more prevalent in caribou associated with the mortality event than in hunter-killed animals from reference sites. Accumulation of hepatic (liver) hemosiderin in Kupffer cells (macrophages) was noted as an indicator of cachexia. Concentrations of lead in feces and liver, copper in the rumen contents, and arsenic in muscle were higher in caribou harvested near Red Dog Mine, as might be expected in that mineral-rich area, but were not at levels of concern for toxicoses. Kidney concentrations of cadmium, which increased significantly with increasing age, present a potential concern for human consumers, and this is an expected finding. We concluded that caribou had starved and that heavy metals had played no role in the mortality event. Further investigation of regional mineral differences is required to understand the sources and transport mechanisms that explain these findings and to properly address mining activity. Mortality events on the north slope of Alaska are common and likely involve starvation as described here, but in most cases they are not investigated, even though recent industrial activities have heightened concern among some local residents and wildlife managers.On a mesuré la concentration en éléments (As, Cd, Cu, Pb, Zn, Fe) et l'état corporel (points limites bruts et histologiques) de caribous (Rangifer tarandus) prélevés lors d'un épisode de mortalité qui s'est produit en 1995 en Alaska, dans la région de Point Hope et de Cape Thompson (y compris le site Chariot). On a comparé ces résultats à ceux de caribous tués par des chasseurs à des emplacements témoins (Barrow et Teshekpuk Lake, en Alaska) et à proximité d'une mine (Red Dog Mine) pour trouver si les métaux lourds avaient joué un rôle dans l'épisode de mortalité ou si la concentration d'un ou plusieurs éléments pouvait constituer un risque pour la consommation humaine. La famine et la malnutrition étaient des facteurs majeurs ayant causé la mort ou une extrême faiblesse, vu que la présence minime ou l'absence de graisse (très basses notes d'état corporel) et une atrophie séreuse de la graisse (observée sous forme de contenu aqueux de la cavité médullaire, sans graisse visible, et à la suite de l'examen histologique) étaient plus courantes chez le caribou associé à l'épisode de mortalité que chez les animaux des emplacements témoins tués par les chasseurs. On a noté dans le foie une accumulation d'hémosidérine hépatique des cellules de Kupffer (cellules macrophages) témoignant d'une cachexie. La concentration de plomb dans les matières fécales et le foie, de cuivre dans le rumen et d'arsenic dans le tissu musculaire était plus élevée chez le caribou provenant de Red Dog Mine, comme on pouvait s'y attendre dans cette zone riche en minéraux, mais cette concentration n'atteignait pas un niveau pouvant provoquer des toxicoses. La concentration de cadmium dans le rein, qui augmentait de façon significative avec l'âge, pourrait constituer un risque pour la consommation humaine, ce qui n'est pas surprenant. On a conclu que les caribous étaient morts de faim et que les métaux lourds n'avaient joué aucun rôle dans l'épisode de mortalité. Il faudrait effectuer des recherches plus poussées sur les différences régionales en minéraux afin de comprendre les mécanismes d'origine et de transport qui expliquent ces résultats et d'aborder comme il le faut les activités minières. Les épisodes de mortalité sont courants sur le versant Nord de l'Alaska et sont probablement liés à la famine, comme le décrit cet article, mais dans la plupart des cas ils ne font pas l'objet d'une enquête, même si l'activité industrielle récente est un sujet qui préoccupe de plus en plus certains résidents et gestionnaires locaux de la faune

Metagenomic survey for viruses in Western Arctic caribou, Alaska, through iterative assembly of taxonomic units

Pathogen surveillance in animals does not provide a sufficient level of vigilance because it is generally confined to surveillance of pathogens with known economic impact in domestic animals and practically nonexistent in wildlife species. As most (re-)emerging viral infections originate from animal sources, it is important to obtain insight into viral pathogens present in the wildlife reservoir from a public health perspective. When monitoring living, free-ranging wildlife for viruses, sample collection can be challenging and availability of nucleic acids isolated from samples is often limited. The development of viral metagenomics platforms allows a more comprehensive

Managing reindeer and wildlife on Alaska's Seward Peninsula

When reindeer (Rangifer tarandus tarandus) were introduced to Alaska's Seward Peninsula between 1892 and 1902, other ungulates were not present and large predators were either absent or less abundant than after reindeer were established. During the next 100 years reindeer numbers and distribution increased and declined precipitously on the Seward Peninsula; wildlife species repopulated this region through natural processes or translocations by man; the non-Native human population of Alaska increased dramatically and wildlife management became an issue of national concern creating diverse public desires regarding resource use; and both range and wildlife became intensively managed through complex, politicized processes. This paper provides an historical overview of reindeer and wildlife abundance on the Seward Peninsula during the 20th century and describes the effects of wildlife on the reindeer industry. Cooperative public processes have been initiated to bring diverse public interests together; meld indigenous, scientific and local knowledge of resources; and supplement governmental wildlife management programmes. Even so, the Seward Peninsula reindeer industry has been severely impacted by wildlife, especially caribou (R. t. granti)

Two caribou mortality events in Northwest Alaska: possible causes and management implications

During fall and winter 1994—1995 and winter 1999—2000, caribou (Rangifer tarandus granti) from the Western Arctic Herd experienced high, localized mortality in northwest Alaska near Cape Thompson. Substantial numbers of caribou wintered in this area during 1986—1987, 2001—2002, and 2002—2003 without suffering high mortality. During the 1994—1995 event, 2000 to 3000 caribou died out of roughly 10 000 that wintered in this area. About 4000 caribou perished out of approximately 20 000 that wintered here during 1999—2000. During both mortality events, gross characteristics and tissue analyses indicated caribou in this area were malnourished. Weather near Cape Thompson during winter 1994—1995 was colder, windier, and had more snow than other years when caribou wintered in this area; in contrast, conditions during 1999—2000 were not unusually severe. Additionally, Cape Thompson experienced 2—5 occurrences of severe conditions during winter 1994—1995 while 1999—2000 experienced only 1 such occurrence at most. Several indicators suggested severe storms killed some caribou before starvation was fatal. Cape Thompson consistently experienced higher wind, lower ambient air temperature, and shallower snow cover than other portions of winter range used by this herd. Unlike years when caribou wintered in this area without experiencing high mortality, caribou were in relatively poor body condition during the autumn that preceded each die-off. Although these mortality events were inconsequential to size of this caribou herd, they raised local residents' concerns that contaminants had poisoned caribou and possibly jeopardized human health. Muskoxen (Ovibos moschatus) in this area were not affected by weather or snow conditions during either caribou mortality event

Two caribou mortality events in Northwest Alaska: possible causes and management implications

During fall and winter 1994—1995 and winter 1999—2000, caribou (Rangifer tarandus granti) from the Western Arctic Herd experienced high, localized mortality in northwest Alaska near Cape Thompson. Substantial numbers of caribou wintered in this area during 1986—1987, 2001—2002, and 2002—2003 without suffering high mortality. During the 1994—1995 event, 2000 to 3000 caribou died out of roughly 10 000 that wintered in this area. About 4000 caribou perished out of approximately 20 000 that wintered here during 1999—2000. During both mortality events, gross characteristics and tissue analyses indicated caribou in this area were malnourished. Weather near Cape Thompson during winter 1994—1995 was colder, windier, and had more snow than other years when caribou wintered in this area; in contrast, conditions during 1999—2000 were not unusually severe. Additionally, Cape Thompson experienced 2—5 occurrences of severe conditions during winter 1994—1995 while 1999—2000 experienced only 1 such occurrence at most. Several indicators suggested severe storms killed some caribou before starvation was fatal. Cape Thompson consistently experienced higher wind, lower ambient air temperature, and shallower snow cover than other portions of winter range used by this herd. Unlike years when caribou wintered in this area without experiencing high mortality, caribou were in relatively poor body condition during the autumn that preceded each die-off. Although these mortality events were inconsequential to size of this caribou herd, they raised local residents' concerns that contaminants had poisoned caribou and possibly jeopardized human health. Muskoxen (Ovibos moschatus) in this area were not affected by weather or snow conditions during either caribou mortality event

Influence of antimicrobial sequence in the nursery on pig performance and economic return

A total of 1,008 pigs (11.9 lb and 19 d of age) were used in a 42-d experiment to determine the influence of antibiotic regimen on growth performance and economic return. From d 0 to 10, pigs were fed diets containing either no antibiotic or Denagard at 35 g/ton and chlortetracycline at 400 g/ton (Denagard/CTC). From d 10 to 21, diets contained no medication, Denagard/CTC, Mecadox at 25 g/ton and Oxytetracycline at 400 g/ton, or Mecadox at 50 g/ton. From d 21 to 42, diets contained either no medication or Denagard/CTC. Adding Denagard/CTC to the diet from d 0 to 10 improved (P 0.49). Overall, MOFC was increased when antibiotics were added to the diet from d 0 to 10 and d 10 to 21 when gain was valued at $0.50 or$1.00/lb and tended to increase (P < 0.06) when Denagard/CTC was added to the diet from d 21 to 42 when the extra gain was valued at $1.00/lb. These results demonstrate that adding antibiotics to the nursery diet improved pig performance and economical return on this commercial farm

Comparison of different antimicrobial sequences on nursery pig performance and economic return

A total of 1,008 weanling pigs (12.0 lb and 19 d of age) were used in a 42-d experiment to compare different antibiotic regimens on growth performance and economic return. From d 0 to 11 and d 11 to 21, pigs were fed diets containing no antibiotic, a combination of Denagard (Novartis Animal Health, Greensboro, NC) at 35 g/ton and chlortetracycline at 400 g/ton (Denagard/CTC), or Pulmotil (Elanco, Greenfield, IN; 363 g/ton from d 0 to 11 and 181 g/ton from d 11 to 21). From d 21 to 42, pigs previously fed Denagard/CTC or Pulmotil were fed diets containing no medication, Denagard/CTC, or a combination of Mecadox (Philbro Animal Health Corp., Ridgefield Park, NJ) at 25 g/ton and oxytetracycline at 400 g per ton (Mecadox/OTC). Adding Denagard/CTC or Pulmotil to the diet from d 0 to 11 and d 11 to 21 improved (P 0.21) in ADG or ADFI between pigs fed Denagard/CTC and pigs fed Pulmotil; however, pigs fed Denagard/CTC tended to have better (P 0.17) in pig performance or IOFC between pigs fed Denagard/CTC and Mecadox/OTC. For the overall trial, adding antibiotics to the diet during any phase improved (P < 0.05) ADG, ADFI, F/G, and IOFC. These results demonstrate that adding antibiotics to the nursery diet improved pig performance and economical return on this commercial farm