Influence of game crops on the distribution and productivity of red-legged partridges Alectoris rufa in Mediterranean woodlands

Abstract

Red-legged partridges Alectoris rufa are one of the most important game species in extensively managed Mediterranean agro-forest systems. Population declines have led to management to increase their populations. This includes the creation of game crops, but their efficacy for red-legged partridges has not been tested. We developed in October 1996 an experimental introduction of 32 100 × 8 m plots in a 6.46-km2 mixed agro-forest system area in Portugal. These plots were planted with either lupin Lupinus sp., vetch Vicea sp. or triticale Triticum aestivum × Secale cereale. The main goal of this study was the evaluation of the potential effect of game crops on partridge distribution and productivity, after controlling for the effect of habitat or other management actions. Partridge abundance and distribution were assessed during spring and summer 1997 by intensive territory mapping. We compared characteristics of territory centres with those of random points in relation to land uses, game crops, and location of water points or supplementary grain sites. The most important variable explaining partridge’s location in spring was the density of supplementary water points. In summer, partridge territories were positively associated with the density of water points and lupin game crops, as well as olive trees. Productivity (number of young per territory in relation to adults observed) increased with the density of lupin game crops, but decreased with density of water points and vetch game crops and proportion of woodland within the territories. Overall, this study suggests that management for partridges in areas of agricultural abandonment, such as those in Mediterranean woodlands, would benefit from the introduction of leguminous game crops and water provision, though more studies are required for a more adequate optimization of these measures of habitat improvement, in particular about the specific cover of the crops and their spatial distribution so they provide adequate resources in summer for nestlings.