Habitat loss on seasonal migratory range imperils an endangered ungulate

Abstract

1. Endangered species policies and their associated recovery documents and management actions do not always sufficiently address the importance of migratory behaviour and seasonal ranges for imperilled populations. 2. Using a telemetry location dataset spanning 1981-2018, we tested for changes in prevalence of migratory tactics (resident, migrant) over time, switching between tactics, shifts in seasonal space use including migration corridors, and survival consequences of migrant and resident tactics for 237 adult female endangered woodland mountain caribou in one population in western Canada. 3. Over more than three decades, the proportion of individuals displaying annual migration to the low elevation forested winter range declined from nearly 100%-38%. Correspondingly, there was a strong switch away from being migrant to being year-round residents at high elevation. 4. These behavioural changes corresponded to abandonment of low elevation winter ranges in association with increasing levels of anthropogenic land uses, including forestry and oil and gas developments. Furthermore, there were no identifiable migration corridors to target for migratory route protection. 5. These shifts translated to lower survival rates, particularly for caribou demonstrating resident tactics, consistent with recent declines of the caribou population. That migrants switched to residency in their largely undisturbed summer range, despite lower survival, indicates maladaptive habitat selection consistent with recent patterns of mountain caribou extirpations. 6. Globally, endangered species policies and their associated recovery plans and management actions often do not explicitly consider the challenge of protecting migratory species. Effective conservation of migratory species requires protecting critical This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Genomic legacy of migration in endangered caribou

“…These results also suggest that the migratory trait, and the set of mutations contributing to the trait could not be easily re-established when lost in a population. Recent findings confirm that migration is imperiled in endangered caribou populations [31]. Genetic mutations, especially those that are beneficial, occur in evolutionary timeframes [92], perhaps incompatible with the fast decline of caribou.…”

“…As a result of habitat alteration caused by anthropogenic activities (including barriers), dramatic declines in populations of migratory ungulates and the disappearance of migratory behavior are now recognized as a global conservation challenge [ 89 , 90 ], with alarming new findings for threatened caribou, in particular [ 31 ].…”

“…Human-caused habitat alterations and climate change are both implicated in caribou decline [ 31 , 91 ] and, together with the extirpation of some populations, ecological and genetic traits could also be extirpated in the future. We document that caribou migration and associated genes are unequally distributed among subspecies, ecotypes, and populations.…”

“…Caribou are wide-ranging and migratory, and many of their populations (also referred to as “herds”, as they might not be genetically or ecologically distinct) are threatened, endangered, or already extirpated [ 26 , 30 ]. In threatened populations of caribou, the proportion of individuals classified as “migrants” can vary dramatically, with some populations reported as being either fully migratory or fully sedentary [ 24 ], and Williams et al [ 31 ] claimed that habitat loss is responsible of the endangerment of migratory caribou in particular. There is therefore a possibility that, under the condition that migratory behavior is genetically determined, those individuals or populations that are migratory will be further impacted by humans (compared to species were migration is not genetically determined).…”

Ecological networks and corridors in the context of global initiatives

“…In order to survive the twin threats of ecosystem fragmentation and climate change, migratory animals need more room to roam in order to survive. Unfortunately, at a time when connectivity needs to be maintained, enhanced, and restored the opposite trend is happening, with movement being truncated, such as global migration routes being shortened and or lost (e.g., Williams et al 2020).…”