Basic and Applied Ecology (May 2023)
Testimonials to reconstruct past abundances of wildlife populations
Abstract
Long-term monitoring of wildlife populations has greatly contributed to our current understanding of population dynamics and ecosystem functioning. Despite tireless field campaigns, however, only a fraction of the biodiversity has been monitored to date and the dynamics of potential key species have yet to be understood.Here, we propose a method based on testimonials of observations from field workers to reconstruct past abundances of unmonitored populations and fill data gaps.We contacted scientists who conducted field work at the Bylot Island field station, Nunavut, in the Canadian Arctic between 1991 and 2019 and collected 205 testimonials of past observations from 131 participants. We scored each testimonial based on its content and derived annual abundance indices for three highly fluctuating taxa, being lemmings, snowy owls and ermines. These indices were compared to standardized abundance estimates based on field sampling that were either available between 1993 and 2019 (lemmings and snowy owls) or 2007–2019 (ermines).Our results show that abundance indices based on testimonials correlate well with those from systematic sampling and can be used to detect ecological phenomena. Moreover, we show that abundance indices were not affected by the effort of participants in the field or the delay between the observations and the collection of testimonials. Finally, we use the received testimonials to generate the longest ermine time series of relative abundance in the Canadian Arctic, spanning 29 years.Monitoring programs and research stations often have access to a pool of past participants (e.g. field workers, ecotourists) whose observations can be localized in time. As we strive to gain a deeper understanding of ecosystem functioning, tapping the memories of these people can provide valuable information on the past abundances of unmonitored populations and help answer hypotheses that would otherwise require years of systematic monitoring.
