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Demographic responses of threatened woodland caribou to annual variation in meteorological and phenological conditions

Craig DeMars

Climate change is expected to increasingly impact populations of woodland caribou and much focus has been placed on how a warming climate has facilitated the northward expansion of apparent competitors (e.g., white-tailed deer) and novel predators (e.g., coyotes). Climate change, however, may also exert effects on caribou populations that are not mediated by predation. Here, we used data from 21 populations in western Canada to assess the demographic response of woodland caribou to annual variation in a suite of meteorological and phenological metrics. Recent research on other ungulate populations suggests that climatic variation may have minimal direct impact on low-density populations such as woodland caribou because per-capita resources may remain sufficient even in “bad” years. We tested this prediction by relating climatic variation to juvenile recruitment and adult female survival, two vital rates with high influence on caribou demography. Contrary to the low-density/low-impact prediction, we recorded relatively strong effects in both rates, though explained variation across all demographic models was low, suggesting that factors other than adverse climatic conditions had a greater influence on caribou demography during our monitoring period (1994–2015). In general, juvenile recruitment was more affected by variation in growing season conditions in the year prior to birth, responding positively to longer, more productive growing seasons and negatively to those that were warmer and drier. Adult female survival, in contrast, was more affected by winter conditions, responding negatively to colder and more variable winters during the monitoring year and up to three years prior. Given these unexpected results, we discuss alternative explanations as to why these woodland caribou populations did not conform to the low-density/low-impact prediction. The demographic effects we recorded have direct implications for caribou conservation, highlighting the increased relevance of recovery actions when adverse climatic conditions are more likely to negatively affect caribou demography.

Wild forest reindeer returns to its historical range – first releases from breeding enclosures in a Finnish reintroduction project

Sakari Mykrä-Pohja, Milla Niemi & Pekka Kilpeläinen

The Finnish wild forest reindeer Rangifer tarandus fennicus occurred throughout Finland still in the 17th century. It was gradually hunted to nationwide extinction by the 1920s but started to re-establish in the 1950s. Nowadays it occurs in Finland and the Western parts of Russia. The total world population is about 4000 individuals. The overall trend has been negative. In 2016, Finland and the EU started a seven-year conservation project WildForestReindeerLIFE. One of the actions is a new reintroduction into two areas in the subspecies’ historical range. This will be carried out through captive breeding and soft releases. Founders both from zoos and from the wild have been moved into two enclosures since autumn 2017. The first calves were born in May 2018. During the autumn 2019, we released 17 individuals of varying age and origin. Eight of them were born in the enclosures. Based on the GPS-tracking, camera traps and field observations, the released animals have mainly stayed close (< 1 km) to the enclosures. In one site, young males made two short-term explorative trips about 20 km distance from the enclosure. In the other site, adult zoo-born female with her calf explored the landscape for some days before settling down near the enclosure. Especially young zoo-born males have been tamer than expected. Near the breeding enclosures, their flight distance could be as short as a few meters, whereas away from the enclosure it appears to be longer. We’ll follow the behavior of released animals in the coming years.

Seasonal patterns of mortality for boreal caribou in the southern Northwest Territories

Allicia Kelly

Seasonality is an important component in shaping the dynamics that influence ecosystems, including mortality. We investigated temporal patterns of mortality in the boreal ecotype of woodland caribou (Rangifer tarandus caribou) in the southern Northwest Territories. Survival data were collected from 423 adult female caribou tracked by radio collars between 2003 and 2018, 172 of which died during the study from predation (106), non-predation (i.e., starvation), (15), harvest (11), accidents (3), or unknown causes (37). We used generalized additive mixed models to evaluate temporal patterns of mortality across the year. We found that probability of mortality followed a trimodal pattern with three peaks, one during pre-calving, one in mid-summer, and a smaller peak in late autumn, with a 6-fold difference in mortality risk between the lowest and highest periods of the year. Mortality risk was higher overall from late spring (pre-calving) to mid-summer than it was from late summer until the end of winter, despite decreasing for about 6 weeks post-calving. We explored potential factors contributing to mortality risk at different times of the year.

Recovery actions for woodland caribou: Predicting and testing the efficacy of habitat restoration

Melanie Dickie

Anthropogenic habitat alteration via land conversion directly reduces habitat availability and disrupts ecological processes. Western Canada’s boreal forest has undergone rapid landscape change as a result of human expansion and resource development. Resulting habitat loss and alteration is hypothesized to be the ultimate cause of boreal woodland caribou declines, one of the most high-profile species at risk in Canada’s boreal forest. While a variety of recovery actions are being employed to recover caribou populations, habitat restoration has been identified as a necessary and important management tool. Restoration is required to restore ecological processes to address the ultimate cause of caribou declines, habitat loss and alteration, as well as the proximate cause, unsustainable predation rates as a result of human-mediated changes to predator-prey dynamics. While the importance of conducting habitat restoration is clear, the effectiveness of restoration treatments is not well understood. Given the spatial extent of these disturbances and the cost of habitat restoration treatments, it behooves researchers and managers to predict and monitor the effectiveness of restoration treatments. Here we explore the predicted success of restoration for recovering caribou populations using predator-prey simulations, and empirically test the effectiveness of restoration treatments. We present a multiple-lines-of-evidence approach for understanding caribou, moose, wolf and bear response to habitat restoration treatments aimed to restore the functional and ecological processes in northeastern Alberta. Understanding behavioral and population-level responses to restoration treatments is necessary to ensure successful recovery and adaptive management.

Indigenizing Science

Morgan Hrycak

Environmental and biological sciences are often siloed from examining Indigenous-related concerns, which can compromise Indigenous rights. Learning about braiding Indigenous ways of knowing and Western Science can be an invaluable way to strengthen relationships and facilitate project support (e.g. on caribou conservation projects). This presentation series will provide perspectives on Indigenous Knowledge and bioethics, decolonizing genomic science, and harvesting rights.

  • Part 1: Perspectives on Bioethics and Research Implications will focus on examples of Indigenous Knowledge, bioethical considerations of scientific research, governance of Indigenous community data, and science communication principles. By knowing these topics, Western scientists can better understand Indigenous concerns on-the-ground. For more information about references used in this presentation, please see the References for Indigenizing Science-Bioethics and Research Implications.
  • Part 2: Chronic Wasting Disease will focus on the decolonization of genomic science, harvesting rights, and the science behind prion diseases. Chronic wasting disease is a fatal nervous system disorder affecting cervids, such as deer and moose. However, Canada’s caribou populations are considered at high risk for this disease. Due to Indigenous connections to the land, understanding chronic wasting disease from Indigenous perspectives can help in understanding and managing the spread of this disease.

Movement, energetics, and demography of Norwegian reindeer

Rebecca Viejou

In Norway, reindeer are fragmented into roughly 23 wild populations and 76 semi-domestic herding districts.  The variation in forage quantity, migratory behaviour, and demography across these populations provide an opportunity to examine the causes and consequences of migration.  In this presentation, I will summarize the results of three studies with the following research goals:

  1. Use forage biomass, digestibility and energy data, and previously defined landscape models of vegetation and geoclimatic variation to develop maps of summer and winter digestible energy across Norwegian reindeer ranges.
  2. Use GPS locations of 304 wild reindeer trajectories to test a series of predictions that follow from the forage quantity hypothesis for migration.
  3. Use 15 years of population data for 43 semi-domestic herding districts to test the basic assumption that migrations provide a demographic benefit.

The results of this work suggest that access to winter ranges with high digestible energy may be an important driver of the large-scale seasonal movements of reindeer, with measurable demographic consequences.

Science to inform policy: Linking population dynamics to habitat for threatened species in Canada

Cheryl Johnson

You can find the published manuscript for this presentation here.

Boreal forests provide numerous ecological services, including the ability to store large amounts of carbon, and are of significance to global biodiversity. Increases in industrial activities in boreal landscapes since the mid‐20th century have added to concerns over biodiversity loss and climate change. Boreal forests are home to dwindling populations of boreal caribou Rangifer tarandus caribou in Canada, a species at risk that requires large, undisturbed landscapes for persistence. In 2012, the Canadian government defined critical habitat for boreal caribou by relating calf recruitment to disturbances. Some have questioned whether the recruitment relationship can be extrapolated beyond the environmental conditions represented in the analysis.

We examined the effects of human disturbances and fire (alone and in combination) on variation in recruitment and adult female survival using data from 58 study areas in Canada. Top models were used in aspatial scenarios of landscape change to evaluate the efficacy of the critical habitat definition in achieving the recovery objectives for boreal caribou in two contrasting landscapes: Little Smoky, dominated by high levels of human disturbances, and the northern boreal shield of Saskatchewan (SK1), dominated by fire.

The top recruitment model suggested the negative effect of fire was three to four times smaller than human disturbances. The top adult female survival model included human disturbances only. These results re‐affirm that human disturbances are the primary factor contributing to boreal caribou declines.

Our aspatial scenarios suggested that undisturbed habitat would have to increase to ≥68% for Little Smoky to maintain a self‐sustaining population of boreal caribou with some degree of certainty. In contrast, the SK1 population was self‐sustaining with 40% undisturbed habitat when fire disturbance predominates, but could become vulnerable with increases in human disturbances (8%–9%).

Policy implications. Boreal caribou are listed as threatened under Canada’s Species at Risk Act. Our results suggest that the 65% undisturbed critical habitat designation in Canada’s boreal caribou Recovery Strategy may serve as a reasonable proxy for achieving self‐sustaining populations of boreal caribou in landscapes dominated by human disturbances. However, some populations may be less or more vulnerable, as illustrated by the scenarios in a landscape dominated by fire (SK1). Continued population monitoring will be essential to assessing the effectiveness of land management strategies developed for boreal caribou recovery, especially with climate change.

Let it grow? Moose response to habitat disturbance in caribou ranges

Laura Finnegan

Boreal caribou winter range in the Central Mackenzie Valley, NWT: What is it, where is it, and how can we manage for it proactively?

Jesse Tigner

Using forecasting tools to inform recovery actions for woodland caribou: a comparison of the tested and the untested

Mariana Nagy-Reis & Chris Johnson

A recurring challenge for resource managers and decision makers is quantifying the trade-offs associated with alternative recovery actions for species-at-risk. Provincial and federal agencies have either employed or planned to employ recovery actions to halt precipitous declines in woodland caribou populations. Nonetheless, testing the efficacy of such actions on the ground is difficult due to insufficient time and limited replication. Here we showcase two modeling approaches developed independently to quantify trade-offs associated with tested and untested recovery actions for woodland caribou, including Linear Feature Restoration/Deactivation, Maternal Penning, Predator Exclosure, Conservation Breeding, Wolf Reduction, and Moose Reduction. More specifically, we compare the estimated costs and demographic benefits associated with each action and discuss knowledge gaps, limitations of tested recovery actions, and uncertainties associated with untested actions. The two case studies demonstrate the utility of forecasting tools to inform recovery actions and guide decisions by explicitly estimating trade-offs associated with actions, which ultimately can be used in structured-decision making approaches to help bridge the gap between management and science.

Application of integrated population models for conservation of at-risk caribou populations

Mark Hebblewhite

Population monitoring can take many different forms, and monitoring elusive and endangered species frequently involves a variety of sparse data from different sources. Small populations are often hard to sample precisely and without bias, so when estimates of vital rates like survival or recruitment point to conflicting population trends, it can be hard to determine which is more correct. Integrated Population Models (IPM) provide an applied statistical framework to reconcile different types of data together in a unified population model. IPM’s help reconcile discrepancies between different data types, missed years, and often lead to increased precision in trend estimates as well. IPM models can also be used to evaluate efficiency of recovery actions. Finally, the process of developing IPM’s also often improves the science of database management, sampling designs, and highlights challenging assumptions and ways of improving efficiency. In this webinar, we highlight three case studies of the application of IPM modeling to the question of trend monitoring of threatened or endangered caribou (Rangifer tarandus caribou) in Alberta, Jasper National Park, and the Central Group of Southern Woodland caribou. All three case studies brought together dozens of biologists, managers, data scientists, and modelers to developed customized Bayesian IPM models to aid trend estimation, and reconcile differences amongst conflicting trends from different data types. In Alberta, we developed a R Shiny App (Eacker et al. Wildlife Society Bulletin) to aid Alberta caribou biologists in the data management processes to efficiently estimate caribou trends across the province using the Hatter-Bergerud R-M Equation. In Jasper National Park, we worked with Park Biologists to integrate data from data from juvenile recruitment surveys, telemetry-based survival, aerial population counts/mark-resight data, and non-invasive capture-recapture DNA data to better understand population status and trend of the South Jasper Local Population Unit. Finally, in the Central Group, we worked with local biologists and First Nations to develop IPMs for the Quintette and Klinse Za that helped test for efficacy of management and recovery actions. IPMs provide a useful, flexible tool for biologists to monitor populations and provides a valuable example of the benefits of integrated population modeling approaches for endangered species management and recovery.