Research

My research to date has been in both aquatic and terrestrial systems, and focuses on applied conservation problems raised by invasive species, parasites and maintenance of wildlife health in a changing climate.


Top: Preliminary map of winter tick distribution in North America by decades, with minimum convex polygons. (Chenery et al, in prep)
Bottom: Winter tick life stages from egg (L) to adult (R). (Image credit: E. S. Chenery) 

Understanding species' spread in a changing climate

Mapping, modelling and analysing range expansion in data-poor species.

The redistribution of biodiversity under climate change presents many unique challenges, particularly in remote northern ecosystems where baseline inventories may be lacking. I am investigating the potential spread of the winter tick (Dermacentor albipictus) parasite into Yukon, by mapping, modelling and analysing this species' distribution over time and space.

This will be the first continental scale map of winter tick presence, and brings together both historic (museum specimens, literature) and contemporary (citizen science) data. This approach is necessary, given the little data available from any single source. Statistical modelling approaches will seek to determine if there are environmental limits guiding where this tick is found, while spatial modelling will explore the feasibility of winter tick movement, given their recorded range.

This data-integration approach should prove of value for other species where data are lacking, but understanding their habitat preferences and potential dispersal is important.


Mechanistic modelling of host-parasite dynamics

Examining the potential effects of changing climatic conditions and host species community on disease dynamics.

Parasite population size is a critical factor that dictates the likelihood of impact on local hosts. I am building mathematical models of the winter tick (Dermacentor albipictus) life cycle to examine how their population size is expected to change, given both changes to climate and host species availability.

Invertebrate species, like the winter tick, have development and survival  rates that are contingent on environmental conditions, such as temperature and relative humidity, and so we may expect a changing climate to have impacts on their life cycle.  Modelling temperature-sensitive parameters will allow me to forecast how tick populations might be expected to change in future at the local scale, and under which conditions epizootic outbreaks are likely to occur. 

Host animals rarely occur in isolation. I will also use these process-based models to examine differences in winter tick population given the host community: moose, elk, caribou and deer (white-tailed and mule). Understanding this is valuable for predicting the effects of various management activities, such as culling, and will help quantify expected success rates.

Top: The annual winter tick life cycle, based on the current global average (Image credit: E. S. Chenery).

Bottom: Life-cycle diagram for mechanistic host-parasite model of winter ticks (Chenery et al, in prep).


Top: EC installing a camera trap in the field. Bottom: Camera capture of an elk in Yukon with characteristic winter tick hair loss on the back of the neck (Image credit: E.S. Chenery) 

Remotely detecting signs of wildlife disease

Quantifying risk of disease transmission and monitoring impact in wildlife using camera traps.

I was awarded a Wildlife Conservation Society (WCS) Canada W. Garfield Weston Fellowship in 2018 and 2019 to support this field research in the Northern Boreal Mountains of Yukon.

Understanding the impacts of disease in wildlife can be challenging, and often relies on invasive techniques to trap and sample animals directly. In collaboration with the Yukon Government, I am using a non-intrusive alternative - high-resolution trail cameras (that automatic photos of passing wildlife) to census the impact of winter ticks on a cervid population in Yukon.

The pathology of winter tick infestation results in highly characteristic hair loss visible on the neck and shoulders of their host animal by March/April each year. Using cameras, I am investigating the potential for monitoring of hair loss patterns in hosts year to year, even in remote areas. These over-winter

Coupled with knowledge of where the larval, host-seeking life stage of winter ticks are found, this method also allows me to model the potential contact rates between different hosts and the ticks. This will provide estimates of which host species (moose, elk, caribou, deer and horses) are most / least at risk of becoming infested, given their habitat selection preferences at key times in the winter tick annual life cycle. 

Understanding the relative risk of disease contact by host species across the landscape will enable wildlife managers and conservationists to make more informed decisions about management and mitigation


Targeting the weakest-link in managing problematic species

Determining the best environmental predictors of presence in an off-host parasite life stage

I was awarded a Wildlife Conservation Society (WCS) Canada W. Garfield Weston Fellowship in 2018 and 2019 to support this field research in the Northern Boreal Mountains of Yukon.

Parasitic species often go through multiple life stages and the success of each directly determines overall population growth and associated host impact. In collaboration with the Yukon Government, I am using traditional flagging techniques to collect the off-host, larval life stage of the winter tick in Yukon, with a view to better understanding their environmental limits in the field.

My study is the first to detect this life stage north of 60o latitude, with all other detections previously being of ticks on-host. Combining measurements of environmental covariates (e.g. temperature, relative humidity) taken in the field, with larval presence and relative abundance will allow me to determine which factors are most associated with this life stage's success.

Understanding the conditions where larvae spend this critical and vulnerable period off-host may therefore provide valuable insight as to the potential range-expansion of winter ticks under climate change.

Top: Questing larval winter ticks in Yukon. (Image credit: E.S. Chenery) Bottom: Number of larvae collected over time in 2019 in Ibex Valley, Yukon (from Chenery et al., submitted).


Utilizing expert opinion to inform model parameters

Forecasting potential secondary-spread of aquatic invasive species using structured expert judgement.

Publication: Chenery, E. S., D. A. R. Drake, and N. E. Mandrak. 2020. Reducing uncertainty in species management: forecasting secondary spread with expert opinion and mechanistic models. Ecosphere 11(4):e03011. 10.1002/ecs2.3011

Predicting the how established invasive species may spread over time is critical for successful management intervention, but substantial uncertainty exists about how species will interact with human pathways when introduced to new ecosystems. We demonstrated a novel approach for quantifying this uncertainty when predicting the uptake, movement, and establishment of invasive species via ballast-water shipping in the Great Lakes (GLB), by combining mechanistic modelling of the spread process with expert opinion of the demographic factors that govern species performance.

Using an online survey method allowed for rapid assessment of 60 aquatic invasive species by 24 experts, we determined a range of parameters describing population growth and establishment potential.   values were combined with a mechanistic model describing the process of ballast-water shipping in the GLB, and scenarios for spread and establishment examined.

We found that most species would be able to establish throughout the GLB within 10 years, under status-quo management conditions. Overall, this joint expert opinion and predictive modeling method demonstrated a novel means of handling sparse data when forecasting invasion dynamics.

Top: Flow-diagram of the expert elicitation process used in this study (Chenery et al., 2020). Bottom: Modelled population growth over time for individual species (lines) grouped by taxa, and the number of lakes established in, in the Great Lakes basin. (Chenery et al., 2020).