Sean Jellesmark

I did my Bachelor degree in Natural Resources at the University of Copenhagen - Faculty of Science. Here I worked with quantifying the effect sociodemographic variables have on nature management and hunting preferences among Danish hunters. My Master thesis was done on the same faculty in collaboration with the Mara Conservancy in Kenya. Field studies were conducted in the Maasai Mara - northern Serengeti ecosystem and used poaching-related data collected during anti-poaching field patrols. The thesis investigated spatiotemporal bushmeat poaching patterns in order to optimize future patrolling effort and identify differences in poaching magnitude between adjacently located regions. Research findings were utilized to identify where and when improved or altered patrolling would benefit but also to emphasize the need for regional-specific political/community solutions to secure future wildlife.


PhD project: Measuring the impact conservation makes on trends in species’ populations

It is hard to quantify the success of conservation actions that aim to reduce extinction risk by maintaining or increasing the abundance of individuals within a population (Hoffmann et al. 2010, 2015, Young et al. 2014). To accurately measure the impact of conservation effort requires comparison against a ‘null model’ to determine what would have happened to the same population in the absence of conservation. Accurately parameterised population models can quantify growth rates and other demographic parameters before and after interventions and this can give an idea of the avoided mortality or additional natality that a population has enjoyed because of conservation intervention.

This project will use population abundance time series data from the Living Planet Index dataset (covering > 20,000 populations, > 4,000 vertebrate species) and the Pan-European Common Bird Monitoring Scheme, and RSPB species monitoring database, as well as ancillary information on conservation interventions for each population from various data sources (e.g., Crees et al. 2016) to model counterfactual population trends, estimate conservation impacts and understand the causal drivers of conservation success.

Observed and counterfactual aggregate extinction risk of ungulate species if no conservation intervention occurred (Hoffmann et al. 2015).



Jellesmark, S., Ausden, M., Blackburn, T.M., Gregory, R.D., Hoffmann, M., Massemino, D., McRae, L., Visconti, P. (2021) A counterfactual approach to measure the impact of wet grassland conservation on UK breeding bird populations. Conservation Biology. Access Repository

Related references:

  • Hoffmann, M., Hilton-Taylor, C., Angulo, A., Böhm, M., Brooks, T.M., Butchart, S.H., Carpenter, K.E., Chanson, J., Collen, B., Cox, N.A., Darwall, W.R. et al. (2010). The impact of conservation on the status of the world’s vertebrates. Science, 330: 1503-1509.
  • Hoffmann, M., Duckworth, J. W., Holmes, K., Mallon, D. P., Rodrigues, A. S., & Stuart, S. N. (2015). The difference conservation makes to extinction risk of the world's ungulates. Conservation Biology, 29: 1303-1313.
  • Crees, Jennifer J., Amy C. Collins, P. J. Stephenson, Helen MR Meredith, Richard P. Young, Caroline Howe, Mark R. Stanley Price, and Samuel T. Turvey.  (2016)A comparative approach to assess drivers of success in mammalian conservation recovery programs. Conservation Biology 30: 694-705.
  • Young, R. P., M. A. Hudson, A. M. R. Terry, C. G. Jones, R. E. Lewis, V. Tatayah, N. Zuël, and S. H. M. Butchart (2014). Accounting for conservation: using the IUCN Red List Index to evaluate the impact of a conservation organization. Biological conservation 180: 84-96.

Academic Host

University College London
London, UK
Tim Blackburn
Richard Gregory


Zoological Society of London
London, UK
Mike Hoffmann
Robin Freeman
Louise McRae
Piero Visconti Collaborator