Page 72 - A bird’s-eye view of recreation - Rogier Pouwels

A bird's-eye view of recreation
contain the most relevant characteristics of the habitat required by the birds that are assessed. Maps are required containing basic recreation data like parking areas and trail networks. Also remote sensing can be used to determine the extent and condition of habitats (Nagendra et al., 2013). When bird data are lacking the procedure cannot be applied. For protected areas, like Natura2000 sites, these might be available by existing monitoring programs (Evans, 2006). Otherwise, managers need to set up an effective monitoring program that will provide information on population densities within their area and also might provide insights into other ecological processes (Lindenmayer and Likens, 2010). Regarding rare species in protected areas monitoring data might be insufficient to derive statistical models. An alternative is to combine information of a wider set of areas to assess the impact of visitor use on population size.
In our procedure we use recreation models to determine the visitor densities in the area. As visitor densities concentrate near parking areas (Beunen et al., 2008, Kendal et al., 2011) and their numbers drop steeply with distance from these parking areas (Jochem and Van Marwijk, 2008) effort should concentrate on validating the location and size of the parking areas in the area. If monitoring data on visitor densities are available these can be used instead. Even spatially scattered data might be useful for validating the output of the recreation models. In our case study no monitoring data for recreation were available. We were therefore unable to calibrate overestimations or underestimations of the visitor densities at the Veluwe. As the relationship between visitor densities and bird densities (e.g. Fig. 2) is based on the output of the recreation models the exact numbers of visitor densities in Appendix 6 should be used with care. However, as the overall assessment uses the same maps for determining the relationship and predicting the bird densities (step b in Fig. 1) an overestimation or underestimation in visitor densities will have no consequence for the overall assessment (step c in Fig. 1). Our results regarding a 50% reduction in Woodlark density for around 55,000 visitor groups per year per hectare (Fig. 2) correspond well with the value of eight disturbance events per hour that Mallord et al. (2007) found for this species in southern England.
The kernel density maps provided the best models for predicting the impact of recreational use on breeding densities for Woodlark and Stonechat while the trail network maps provided the best model for Nightjar. The main difference between Nightjar and the other two species in relation to disturbance by outdoor recreation is that Nightjar is a nocturnal species. Breeding pairs are not actively foraging during daytime when visitors are present. It is however unclear whether this is reflected in the
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