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Sheila Colla

Sheila Colla

Picture of Sheila Colla
Sheila Colla
Associate Professor

Eligible to Supervise

Biology Graduate Program


Students in my lab are exposed to a broad range of bee research not just through international and inter-university collaborations, but also through the excellent bee research group at York, comprised of Professors Colla, Packer and Zayed and their students, PDFs and academic visitors.

Research Focus

I am a classically trained Ecologist using scientific principles to address real-world conservation issues. My research thus far has focused on the conservation of lesser understood native species such as bees, butterflies and flowering plants. As pollinators and pollination have become important issues among policymakers and the public in recent years, my work has become more interdisciplinary. I work closely with environmental NGOs, landowners, academic partners and government agencies at the municipal, provincial and federal levels to implement conservation management based on the best available science. My research considers species with large ranges across the US and Canada but also local species which are at-risk here in Ontario.

Representative Publications

Nalepa, R., Epstein, G., Pittman, J., & Colla, S. (2021). Perceptions of wild bees and farm characteristics associated with the uptake of pollinator-supporting land management practices among Canadian apple growers. Renewable Agriculture and Food Systems, 36(4), 334-343. doi:10.1017/S1742170520000344

Amanda R Liczner, Sheila R Colla. (2020). One‐size does not fit all: at‐risk bumble bee habitat management requires species‐specific local and landscape considerations.

VMacPhail VJ, Gibson SD, Hatfield R, Colla SR. 2020. Using Bumble Bee Watch to investigate the accuracy and perception of bumble bee (Bombus spp.) identification by community scientists. PeerJ 8:e9412

Colla, Sheila R., and J. Scott MacIvor. Questioning public perception, conservation policy, and recovery actions for honeybees in North America. Conservation Biology 31.5 (2017): 1202-1204.

Colla, Sheila R. Status, threats and conservation recommendations for wild bumble bees (Bombus spp.) in Ontario, Canada: A review for policymakers and practitioners. Natural Areas Journal 36.4 (2016): 412-426.

J.T. Kerr, A. Pindar, P. Galpern, L. Packer, S.G. Potts, S.M. Roberts, P. Rasmont, O. Schweiger, S.R. Colla, L.L. Richardson, D.L. Wagner, L.F. Gall, D.S. Sikes, A. Pantoja (2015) Climate change impacts on bumblebees converge across continents. Science 349:177-180.

Colla, S.R., F. Gadallah, L. Richardson, D. Wagner & L. Gall (2012) Assessing declines of North American bumble bees (Bombus spp.) using museum specimens. Biodiversity and Conservation 21:3585-3595.

Szabo, N., S.R. Colla, D. Wagner, L. Gall & J. Kerr (2012) Is pathogen spillover, habitat loss or pesticide use responsible for North American wild bumblebee declines? Conservation Letters 5: 232-239.

Colla, S.R, E.Willis, & L.Packer. (2009) Can green roofs provide habitat for urban bees? Cities and the Environment (2):1 [Online]

Williams, P., S. Colla & Z. Xie. (2009) Bumblebee vulnerability: common correlates of winners and losers across three continents. Conservation Biology 23: 931-940.

Colla, S.R. & L. Packer (2008) Evidence for decline in eastern North American bumblebees (Hymenoptera: Apidae), with special focus on Bombus affinis Cresson. Biodiversity and Conservation 17: 1379-1391.

Colla, S.R., M.C. Otterstatter, R.J. Gegear & J.D. Thomson (2006) Plight of the bumblebee: Pathogen spillover from commercial to wild populations. Biological Conservation 129: 461-467.

Williams, P., R. Thorp, S.R. Colla & L. Richardson. (2014) A Field Guide to the Bumblebees of North America. Princeton University Press. 208 pp.


Ecology, conservation biology, environmental policy, sustainable agriculture

Research Areas

Ecology and Evolutionary Biology