10 Years - Feeding The Wolves.zip
Hercules Montero
From 1995 to 2000, in early winter, elk calves comprised 50% of wolf prey, and bull elk comprised 25%. That ratio reversed from 2001 to 2007, indicating changes in prey vulnerability and availability. Although elk is still the primary prey, bison has become an increasingly important food source for wolves. While there is some predation on bison of all age classes, the majority of the consumption comes from scavenging winter-killed prey or bison dying from injuries sustained during breeding season. The discovery of these changes emphasizes the importance of long-term monitoring to understand predator-prey dynamics. Changes in wolf predation patterns and impacts on prey species like elk are inextricably linked to other factors, such as other predators, management of ungulates outside the park, and weather (e.g. drought, winter severity). Weather patterns influence forage quality and availability, ultimately impacting elk nutritional condition. Consequently, changes in prey selection and kill rates through time result from complex interactions among these factors. Current National Park Service (NPS) research focuses on the relative factors driving wolf predation over the past 25 years.
In the first years following wolf restoration, the population grew rapidly as the newly formed packs spread out to establish territories with sufficient prey. The wolves have expanded their population and range, and now are found throughout the GYE.
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Carnivora
- Family: Canidae (dog family)
- Genus: Canis (Latin word meaning "dog")
- Species: lupus (Greek word meaning "wolf")
- Common names: gray wolf, timber wolf
- Names in other languages: Lobo (Spanish), Loup (French), Lupo (Italian), Varg (Swedish), Ulv (Norwegian)
- Average body mass: males 110 pounds (50 kg); females 90 pounds (41 kg)
- Heaviest known wolf in Yellowstone: 148 pounds (wolf 760M of Yellowstone Delta pack with no food in stomach)
- Average height at shoulder: males 81 cm, females 77 cm
- Average length: 181 cm
- Eyes: blue at birth, light yellow to gold to brown as an adult
- Number of bones: 319 males, 318 females
- Number of teeth: 42
- Dental formulae: incisors 3 top/3 bottom, canines 1/1, premolars 4/4, molars 3/2 (on each side)
- Pelage: gray or black (ratio 50:50), rarely white
- Black coat color: caused by K-locus gene thought to have originated from historic hybridization with domestic dogs 500-14,000 years ago
- Locomotion: tetrapedal, digitigrade
- Average rate of speed: 5 miles/hour (8 kph)
- Top speed: 35 miles/hour (56 kph)
- Body temperature: 100-102.5 F (37.3-39.1 C)
- Respiration: 10-30 breathes per minute
- Heart rate: 70-120 beats per minute
- Bite pressure: 1,200 psi
- Smell: excellent, although unmeasured. Estimated to be thousands of times better than humans
- Vision: excellent night vision; no red or green cones, but have blue and yellow cones
- Hearing: little is known, but probably similar to dogs (relatively normal hearing abilities compared to other mammals)
- Howling function: many uses, including intrapack communication, advertising territory, coordinating social activities
- Distance howling can be heard: forest=11km (6.6 mi), open areas=16 km (9.6 mi)
- Feeding habits: generalist carnivore; scavenges when possible and has been known to eat small amounts of vegetation
- Primary food sources in Yellowstone: Winter: elk (>96%), bison (3-4% and increasing in recent years; deer (1.5%); Spring: elk (89%), bison (7%), deer (7.1%); Summer: elk (85%), bison (14.1%), deer (5 years old: 18%
- Current North American population: 67,100-74,100 (53,600-57,600 of these in Canada)
- Average home range size in Yellowstone (northern range): 274 km2 (range=58-1,151 km2)
- Average home range size in Yellowstone (interior): 620 km2 (range=105-1675 km2)
- Average home range size in Yellowstone (park-wide): 428 km2
- Group of wolves: pack/ family (one of few eusocial species)
- Average pack size in Yellowstone: 9.8
- Largest pack recorded in Yellowstone: Druid Peak, 37 wolves (2001); may be the largest ever recorded (42 wolves seen together in Wood Buffalo National Park (1974) but unknown if they were a single pack)
- Percent of population that are lone wolves in Yellowstone: 2-5%
- Percent of population that are lone wolves in North America: 10-15%
- Sex ratio: 50:50
- Mating: usually monogamous, but about 25% of packs have multiple breeding pairs under polygymous matings
- Courtship: mid-February
- Gestation: 63 days
- Birth period: mid-April
- Birth location: den
- Typical dens: excavated under large roots, boulders, hillsides, caves with a tunnel leading to an enlarged chamber; several entrances and chambers may be present
- Den emergence: 10-14 days
- Average litter size in Yellowstone: 4.4 at den emergence, 3.2 survive until late December
- Maximum litter size recorded in Yellowstone: 11
- Split litters: multiple fathers per litter have not been detected in wild gray wolves
- Weaning: 5-9 weeks from milk, then brought food (regurgitation) for another 3 months
- Milk content: 6.6% fat; 144 kCal per 100 grams
- Rendezvous sites: used as wolf pups get older as a central homesite; time spent there and number of homesites varies widely between packs
- Average female age at first litter in Yellowstone: 2.7
- Oonset of female reproduction senescence: 4-5 years
- Interbirth interval: can be every year
- Eyes open: 12-14 days
- Dispersal: both sexes, YNP average age 2 years, 1 month; range 1-4 years
The foraging and feeding ecology of gray wolves is an essential component to understanding the role that top carnivores play in shaping the structure and function of terrestrial ecosystems. In Yellowstone National Park (YNP), predation studies on a highly visible, reintroduced population of wolves are increasing our understanding of this aspect of wolf ecology. Wolves in YNP feed primarily on elk, despite the presence of other ungulate species. Patterns of prey selection and kill rates in winter have varied seasonally each year from 1995 to 2004 and changed in recent years as the wolf population has become established. Wolves select elk based on their vulnerability as a result of age, sex, and season and therefore kill primarily calves, old cows, and bulls that have been weakened by winter. Summer scat analysis reveals an increased variety in diet compared with observed winter diets, including other ungulate species, rodents, and vegetation. Wolves in YNP hunt in packs and, upon a successful kill, share in the evisceration and consumption of highly nutritious organs first, followed by major muscle tissue, and eventually bone and hide. Wolves are adapted to a feast-or-famine foraging pattern, and YNP packs typically kill and consume an elk every 2-3 d. However, wolves in YNP have gone without fresh meat for several weeks by scavenging off old carcasses that consist mostly of bone and hide. As patterns of wolf density, prey density, weather, and vulnerability of prey change, in comparison with the conditions of the study period described here, we predict that there will also be significant changes in wolf predation patterns and feeding behavior.
I am struck by the growing gap between what I experience in my consulting work and the way our society is portrayed by the news. Our political reporting would suggest that no one works for the country any more, that they are all focused on themselves or their party. The news is feeding this narrative and that action makes the narrative stronger. However, in my day-to-day life, I find people across the political spectrum can and will work together to make their communities stronger and more equitable for all.
Biologist Raymond Coppinger Coppinger has another idea: the wolves domesticated themselves. He suspects that the process would have begun at the end of the last Ice-Age approximately 15,000 years ago when people began to gather and live in one place for the first time. The appearance of these villages was fairly rapid and coincidental with the fossil evidence of dogs as we know them.
Wolves are skilled at identifying vulnerable prey and tend to target old, young, sick or otherwise weakened individuals. Hence, deer removed by wolves are less likely to survive and less likely to produce offspring than the deer that remain. The average age of white-tailed deer killed by wolves was 6.5 years in Minnesota, for example, whereas the average age of does taken by hunters was 2.5 years in this same area. This targeting of vulnerable animals serves to reduce the impact of wolves on long-term deer population dynamics. It has also been suggested that wolves might reduce CWD transmission rates and prevalence by removing sick individuals.