SummaryIllegal killing/taking of birds is a growing concern across the Mediterranean. However, there are few quantitative data on the species and countries involved. We assessed numbers of individual birds of each species killed/taken illegally in each Mediterranean country per year, using a diverse range of data sources and incorporating expert knowledge. We estimated that 11-36 million individuals per year may be killed/taken illegally in the region, many of them on migration. In each of Cyprus, Egypt, Italy, Lebanon and Syria, more than two million birds may be killed/taken on average each year. For species such as Blackcap Sylvia atricapilla , Common Quail Coturnix coturnix , Eurasian Chaffinch Fringilla coelebs , House Sparrow Passer domesticus and Song Thrush Turdus philomelos , more than one million individuals of each species are estimated to be killed/ taken illegally on average every year. Several species of global conservation concern are also reported to be killed/taken illegally in substantial numbers: Eurasian Curlew Numenius arquata , Ferruginous Duck Aythya nyroca and Rock Partridge Alectoris graeca . Birds in the Mediterranean are illegally killed/taken primarily for food, sport and for use as cage-birds or decoys. At the 20 worst locations with the highest reported numbers, 7.9 million individuals may be illegally killed/ taken per year, representing 34% of the mean estimated annual regional total number of birds illegally killed/taken for all species combined. Our study highlighted the paucity of data on illegal killing/taking of birds. Monitoring schemes which use systematic sampling protocols are needed A-L. Brochet et al. 2 to generate increasingly robust data on trends in illegal killing/taking over time and help stakeholders prioritise conservation actions to address this international conservation problem. Large numbers of birds are also hunted legally in the region, but specific totals are generally unavailable. Such data, in combination with improved estimates for illegal killing/taking, are needed for robustly assessing the sustainability of exploitation of birds.

Summary1. Studies of diet choice usually assume maximization of energy intake. The well-known 'contingency model' (CM) additionally assumes that foraging animals only spend time searching or handling prey. Despite considerable empirical support, there are many foraging contexts in which the CM fails, but such cases were considered exceptions rather than the rule. 2. For animals constrained by the rate at which food is digested, CM does not necessarily lead to maximal energy intake rates because the time for digestion is not part of the selection criteria. In the main model developed to explain diet choice under a digestive constraint, the 'digestive rate model' (DRM), time lost to digestive breaks is minimized so that energy intake over total time (searching, handling, digestive breaks) is maximized. 3. It is increasingly acknowledged that most animals may face digestive constraints as prey capture rates vary over time and as it would be a waste to carry around heavy digestive machinery that can rapidly process food under all circumstances: this is only needed in times of high demand, provided that enough food can be found. 4. In molluscivore shorebirds ingesting hard-shelled prey such as red knots (Calidris canutus), the predictions of DRM were held up so far, whereas those of CM were rejected. However, most tests were carried out under controlled experimental conditions. Red knots overwinter in coastal areas over much of Western Europe and we capitalized on this variation by comparing, during a single winter, observed diet composition with predictions of DRM, CM and a null model assuming no prey selection ('no-selection model', NSM). 5. The observed diets were best predicted by DRM followed by CM. NSM poorly predicted observed diet choice. Under the present conditions, diet choice based on DRM would on average have yielded an energy intake rate twice as large as one based on CM. By adjusting the size of their gizzard (held constant in the present simulations), red knots could have lifted their energy intake rate further. We suggest that application of the DRM can help many diet studies forward, especially those previously seen as exceptions to the classical CM-based rule.

Local studies have shown that the distribution of red knots Calidris canutus across intertidal mudflats is consistent with the predictions of an ideal distribution, but not a free distribution. Here, we scale up the study of feeding distributions to their entire wintering area in western Europe. Densities of red knots were compared among seven wintering sites in The Netherlands, UK and France, where the available mollusc food stocks were also measured and from where diets were known. We tested between three different distribution models that respectively assumed (i) a uniform distribution of red knots over all areas, (ii) a uniform distribution across all suitable habitat (based on threshold densities of harvestable mollusc prey), and (iii) an ideal and free distribution (IFD) across all suitable habitats. Red knots were not homogeneously distributed across the different European wintering areas, also not when considering suitable habitats only. Their distribution was best explained by the IFD model, suggesting that the birds are exposed to interference and have good knowledge about their resource landscape at the spatial scale of NW Europe, and that the costs of movement between estuaries, at least when averaged over a whole winter, are negligible.