Monitoring wader breeding productivity

Severe declines in widespread wader species like Lapwing, Black-tailed Godwit, Redshank and Curlew have been recorded in Western Europe from the latter part of the twentieth century onwards. In many populations not enough young are fledging each year to maintain population stability: this low breeding productivity is driven by complex and interactive factors such as afforestation, nest destruction and chick mortality associated with agricultural activities, and increased rates of nest and chick predation. To deliver effective conservation interventions and stabilise populations, accurate monitoring of wader breeding productivity at large-scales is needed.

To help inform development of these schemes, in this paper we reviewed published studies that estimate wader breeding productivity (excluding nest monitoring approaches because they are difficult to deploy at scale). The studies we reviewed can be arranged into three broad categories based on the type of metric produced: i) ‘hatching success’; ii) ‘fledging success’; and iii) ‘young fledged per pair’, from the coarsest metric to the most precise. Key factors which influence study design and  determine which metric is most suited to a given species and habitat are i) breeding densities, which influence whether it is feasible for fieldworkers to re-find individual pairs; ii) the availability of experienced fieldworkers who can accurately discern brood-rearing behaviours; iii) renesting rates, which influence when brood-rearing behaviours or fledged young can be recorded; and iv) whether the vegetation structure during the chick-rearing period and the species ecology allows fieldworkers to accurately count young. The importance of habitat can’t be overlooked: for Curlew, for example, all three metrics (hatching success, fledging success and young fledged per pair) have all been produced in different contexts – In low density populations in lowland arable areas, young fledged per pair has been estimated, while in upland studies with higher breeding densities, hatching success is more often used. What works for a species in one context won’t make sense somewhere else, because breeding densities, resources, the availability of suitable vantage points and vegetation structure can vary so much across a species’ range.

We hope this piece of work is useful in providing national environment agencies, funders, researchers, volunteer groups, fieldworkers and land managers a useful resource when developing schemes to monitor wader productivity.