Transplants in Southeast Alaska

and the consequences of forced emigration

Since the 1920s, mammals of fourteen species have been transplanted from one location (mostly but not always in Alaska) to another location in Southeast. Many of the official transplants were done with the hope of establishing viable populations of game species in new places, with the goal of providing more prey for humans. The processes of capturing and transporting the unwilling immigrants commonly resulted in high mortality, even before the animals were deposited in their new sites.

Many of the transplantations failed. An attempt to establish a moose population near the Chickamin River in the 1960s failed altogether; all the transplanted young moose died. At that time, officials declared it was too expensive to do a preliminary habitat assessment and thought it more practical to just dump the moose there and see what happened. A number of other transplant attempts over several decades are said to have failed: deer to the Taiya Valley, goats to Chichagof, mink to Strait Island, muskrats and marmot to Prince of Wales, wolf to Coronation Island, snowshoe hare to Admiralty and other islands. Ill-advised attempts in the 40s and 50s to establish populations of non-native raccoons failed.

Some transplants were successful, apparently without any serious preliminary assessments: the mountain goats now living on Baranof are descendants of the transplants in the 1920s, and marten were moved to Prince of Wales, Baranof, and Chichagof in the 1940s and 1950s. After a habitat assessment in Berners Bay, a number of young moose were deposited there in 1958 and 1960; they established themselves successfully and that local population has grown. It may be emigrants from that area that we observe near Cowee Creek, Herbert River, and the Mendenhall Glacier. The possible effects of moose browsing on the structure of the vegetation in Berners Bay are apparently not known; given the notable cropping of willows and other shrubs in Gustavus, one might wonder about the effects on nesting habitats for birds—especially in the light of research elsewhere documenting that over-browsing can drastically reduce bird habitat.

Elk (a non-native species) were brought to four islands in Southeast in the mid to late 1900s. The elk, from Oregon and Washington, were exchanged for mountain goats from Alaska. Only the 1987 introduction of elk to Etolin Island was successful, and elk eventually dispersed from there to nearby Zarembo and other islands. Some preliminary habitat assessments were made, but post-facto concern about possible competition with existing deer populations arose, so continued monitoring and perhaps management are necessary.

After marten were transplanted to the three big islands, red squirrels were often introduced as prey for marten. It later became clear that marten really prefer voles and it is unlikely that the squirrel transplants had much effect on the introduced marten populations. However, it is very likely that the squirrels are having a negative impact on nesting birds on those islands, because they prey on eggs and nestlings.

Collectively, these attempts to establish new populations of mammals are a very mixed bag. There was a high cost in mortality of animals (not to mention dollar costs of capture and transport), many transplant efforts failed, and there was little attention paid to possible consequences. The impetus for game translocations in Southeast may have abated somewhat, and as our ecological understanding has grown over the years, it seems likely that any further transplants would be done with greater concern not only for the animals themselves but also for proper preliminary assessments and the ecological consequences.

Several additional transplants were done in attempts to augment existing populations or to re-establish a previously resident population. However, the effect of adding new animals to an existing population (deer to Kupreanof in 1979, for example) is usually not known. A transplant effort in 1989 attempted to restore a much-reduced population of mountain goats on Mt Juneau, with the stated intent of improved wildlife viewing (!). All the transported goats initially moved away, but by the early 2000s, goats were again seen on the ridge, although no one seems to know if these animals are related to the transplants or from a natural population on nearby ridges.

Sea otters have been re-introduced to many places in Southeast at various times, to restore the natural population that was extirpated by human activity. These transplants are apparently successful and the population of sea otters in Southeast is growing. The consequences of sea otter presence are currently being studied by faculty and students of UAF.

The historical information in this essay derived from Tom Paul’s 2009 ‘Game Transplants in Alaska”, ADFG Technical Bulletin #4. In addition to the official transplantations, there have been an unknown number of unofficial and mostly unrecorded ones, done by private citizens.

The ecology of fear

the far-reaching effects of a universal emotion

What do animals do when they are frightened? They increase vigilance, scanning their surroundings with all available senses. Some ‘freeze’ in hopes that immobility renders them invisible. Some hide, in the best available cover. And some run. Any of those responses interferes with other necessary activities. In addition, the bodies of frightened animals respond to fear by increasing the production of stress hormones, and that increases the heart rate, the metabolic rate, and thus the expenditure of energy. Prolonged fear adds negative impacts on the immune system and reproductive physiology. All of these negative effects have consequences not only for individual animals but for their populations.

It doesn’t much matter if the cause of fear is a real threat or something merely perceived to be threatening. Failure to evade a threat bears a high cost and is often lethal, so even a perceived threat generally necessitates a reaction, just in case it is real. Play it safe, so you have a chance to play another day!

The importance of a perceived risk of predation was shown experimentally in a population of song sparrows in British Columbia. The perceived risk of predation was manipulated by using playbacks of predator calls, every few minutes all day and night long, four days on followed by four days off, throughout the entire nesting season. Some nests were exposed to various kinds of predator calls, such as hawk, owl, crow, and raccoon; as a control for the generation of extra noises, other nests were exposed to calls of non-predators (loon, goose, seal). Playbacks began well before female sparrows built their nests.

Nests were located before any eggs were laid. Direct predation on nests was prevented by netting and electric fencing, and video cameras recorded the entire nesting cycle.

The results for song sparrow reproduction were striking. Female sparrows exposed to predator calls built their nests in denser vegetation than those exposed to non-predator calls. Nests exposed to predator playbacks contained fewer eggs and hatching success was lower. Females with nests exposed to predator calls were jumpier, left the nest more often and stayed away longer, with the result that their chicks got chilled. Chicks in nests exposed to predator calls were fed less often by their parents, so they weighed less. As a consequence of chilling and fewer food deliveries, chick mortality was higher than in nests exposed to non-predator calls. The reproductive output of the population of sparrows with the perceived risk of predation was reduced by forty percent, compared that of the population without the perceived risk. It is likely that the ultimate difference between the two populations was even greater than forty percent, because deprivation during growth usually has continuing negative effects into adulthood.

Other studies have shown similar effects of perceived predation risk on the biology of other species, including elk and snowshoe hares. When hares were regularly exposed to the mere presence of a dog (a potential predator), their stress hormones increased. Females then produced smaller litters and the young hares (leverets) were unusually small and thin.

In addition, the risk of predation commonly affects where animals live and so can limit the availability of suitable habitat. For example, marmots avoid habitats where the detection of predators is impaired. Juvenile salmon and several other freshwater fishes avoid habitats pervaded by alarm cues from the bodies of dead or injured companions (although risk taking is likely to increase if the animals are not well fed). In the presence of tiger sharks near Australia, dugongs became wary and tended to move into different areas. Bears become less active in daytime and more active at night when close to roads and development. Wildlife abundance and activity is known to be lower near trails frequented by dogs.

By constraining habitat use, predation or risk of predation also affects foraging opportunities. For example, brown bears are dominant over black bears, which may avoid salmon streams visited frequently by brown bears; in such areas, black bears consume fewer salmon than where brown bears are scarce. Female bears, both black and brown, with cubs often avoid salmon-spawning areas frequented by male bears, to reduce the risk of infanticide; they have reduced intake of salmon and lighter-weight cubs as a result. For bears, fat mamas tend have bigger cubs and to be more successful in cub-rearing than thinner females, so risk avoidance has a cost (presumably a lower cost than with infanticide, however).

It is clear that predation risk and the perception of risk affect not only the behavior of individuals but also have probable consequences for animal populations, by affecting reproductive output. Furthermore, the consequences of fear may extend beyond the species that is directly exposed to the risk of predation, with cascading effects through the network on interacting species, although the magnitude of such effects probably varies greatly.

An example is found in invertebrates: when grasshoppers are stressed by the risk of predation by spiders, their body composition changes. Then, when the grasshoppers die and decompose, their altered chemistry slows the subsequent decomposition of the leaf litter. So materials are recycled more slowly, with other consequences still to be recorded.

A far more dramatic example was seen when elk in Yellowstone changed their patterns of habitat use to avoid wolves, moving uphill and losing much of the lush foraging near the streams. However, many other components of that ecosystem changed for the better. Vegetation near streams was no longer over-browsed; willows, aspens, cottonwoods recovered, which helped stabilize stream banks and improve fish habitat. When their major food plants (just mentioned) recovered, beavers moved back in, creating ponds that support fish, amphibians, and lots of insects on which other animals feed. Berry bushes also rebounded and were again able to produce good crops of berries, which feed bears, birds, and other animals. Good shrub cover in the streamside zones provides important nesting and foraging sites for songbirds, including Neotropical migrants. In short, dozens of species and the entire ecosystem benefit from a reduction of elk browsing in this area.