Mapping range dynamics from opportunistic data: spatiotemporal modelling of the lynx distribution in the Alps over 21 years

Abstract

The Eurasian lynx is of special conservation concern based on the European Union's Habitat Directive and its populations need to be maintained or restored at favourable conservation status. To evaluate lynx population status, appropriate monitoring needs to be in place. We modelled the distribution dynamics of lynx in the Alps (200 000 km 2 ) during 1994-2014 at a resolution of 100 km 2 . Lynx distribution and detection probability varied by year, country, forest cover, elevation and distance to the nearest release site. Occupancy of neighbouring quadrats had a strong positive effect on colonization and persistence rates. Our analyses demonstrate the importance of accounting for imperfect detection: the raw data underestimated the lynx range by 55% on average, depending on country and winter. Over the past 20 years the Alpine lynx range has expanded at an average rate of 4% per year, which was partly due to the lynx translocations to new areas. Our approach to large-scale distribution modelling and analysing trends using site occupancy models can be applied retrospectively and is useful in many cases where a network of trained people is established to report the presence of target species, for example, in Europe where member states of the European Union have to report conservation status of species of community interest. Hence, dynamic occupancy models are an appealing framework for inference about the large-scale range dynamics based on opportunistic data and a useful tool for large-scale management and conservation programmes.

Use of ambiguous detections to improve estimates from species distribution models

“…In particular, citizen participation increases the ability to survey large areas over extended periods, an effort that would be costly if done by professionals only (Molinari‐Jobin et al. ). A primary goal of citizen science (CS) is to produce reliable data and information that scientists or decision makers can use (McKinley et al.…”

“…Usually large carnivores are surveyed with indirect methods, for example, observations of tracks, scat, and prey remains or use of camera traps (Molinari‐Jobin et al. ). Observations are then filtered by experts to assess the reliability of evidence of the observed presence.…”

“…Recent studies of the distribution of European large carnivores have been based on only reliable observations, that is, those remaining after discarding ambiguous detections and validation by experts (Molinari‐Jobin et al. ). This means that some observations are discarded, even though they may contain relevant ecological information on the species distribution.…”

“…We applied these methods to an SDM of the Eurasian lynx ( Lynx lynx ) in the European Alps (Molinari‐Jobin et al. ). We expected improved precision in ecological parameter estimates when all data were included in an analysis, despite having to accommodate additional nuisance parameters to deal with misidentification.…”

Estimating abundance with interruptions in data collection using open population spatial capture-recapture models

“…Compared to a series of independent SCR models, OPSCR models use detections and model population dynamics and individual movement between several consecutive sampling occasions. As a result, individual detections in previous and/or subsequent occasions inform the Markovian model about the spatial location and demographic status of each individual and help determine its fate (Molinari et al (2018); Figure 1). This explains the increase precision of the estimates for gaps framed by multiple occasions with data (Figure 3, scenario 11011).…”