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The release of farm-reared game birds for hunting is an increasingly common game management practice. However, releasing could have negative effects on sympatric wild species, for example, through parasite transmission. Here, we document the spatial-temporal patterns and intensity of red-legged partridge releases in the province of Ciudad Real, Spain, over a 15-year period (2002–2016), relating them to local changes in the abundance of little bustards estimated from two surveys carried out in 2005 and 2016. Within the province, > 600,000 red-legged partridges were released annually over at least 20% of the area. Releasing intensity varied between estates and fluctuated over the 15-year study period, probably because of an economic crisis during 2008–2014. Overall, numbers of little bustards dropped by 46% between surveys, the decrease being more marked in the west of the province. Contrary to expectation, the only hunting estates where little bustards did not decrease were those with higher release intensity. This may be a consequence of management measures or other factors that benefit little bustards and are more prevalent on those estates than elsewhere, such as game crop provision, predator control or habitat quality. [ABSTRACT FROM AUTHOR]

Anthropogenic activities, such as the translocation or introduction of animals, may cause a parallel movement of exotic parasites harboured by displaced animals. Although introduction and/or relocation of animals for hunting purposes is an increasingly common management technique, the effects of gamebird release as a major vehicle for the introduction of parasites into new geographic regions have rarely been reported. We examined the prevalence and distribution of avian malaria parasites infecting resident avian hosts (red-legged partridge Alectoris rufa) at a local scale, with a particular emphasis on the effects of releasing farm-reared birds for hunting on the spatial and temporal structure of the parasite community. We collected blood samples from adult partridges from two game estates with partridge releases and two sites without releases over two periods (spring and autumn). We tested the probability of infection and differences in the parasite community in relation to the management model (releases vs. non releases) and sampling period, comparing autumn (when farm-reared birds are released) and spring (after hunting season, when mostly wild birds can be found in the population). We found a high prevalence (54%) of Plasmodium spp., and substantial differences in the spatial and temporal distribution of parasite lineages among the populations studied. Some parasite lineages occurred at high frequencies in game estates without introduction of farm-reared partridges, while other lineages were more abundant in game estates with releases than in those without releases. Overall, the prevalence of avian malaria was similar between spring and autumn at non-release sites, whereas in sites with releases, it was higher in autumn than in spring—probably due to artificial restocking with infected farm-reared birds at the onset of the hunting season. In short, humans may be an important agent driving the alteration of the spatial structure of local parasite fauna via the introduction of exotic parasites by gamebird release, which could cause avian malaria outbreaks with severe repercussions for native avifauna.

The mallard ( Anas platyrhynchos L.), the most abundant waterfowl species, is an important migratory component of the Holartic fauna. In Europe, massive numbers of farm-reared mallards of unknown genetic origin are released into the wild for hunting and in urban areas for ornamental purposes. Human manipulations have caused shifts in range, influenced migration propensity, led to behavioural modifications and altered the genetics of this duck species. With the aim to contribute to knowledge on the genetic consequences of large-scale game releases of mallards in southern Europe, we analysed the relationship among 245 individuals (wild and captive-bred) from eight localities in central and northern Italian regions and four from North America, by using nine microsatellite loci. In most Italian sites, a large admixture of mallard strains were observed, whereas significant genetic differentiation levels were found between urban and wild populations and among the wild population from North America and all European populations. [ABSTRACT FROM AUTHOR]

Anthropogenic activities, such as the translocation or introduction of animals, may cause a parallel movement of exotic parasites harboured by displaced animals. Although introduction and/or relocation of animals for hunting purposes is an increasingly common management technique, the effects of gamebird release as a major vehicle for the introduction of parasites into new geographic regions have rarely been reported. We examined the prevalence and distribution of avian malaria parasites infecting resident avian hosts (red-legged partridge Alectoris rufa) at a local scale, with a particular emphasis on the effects of releasing farm-reared birds for hunting on the spatial and temporal structure of the parasite community. We collected blood samples from adult partridges from two game estates with partridge releases and two sites without releases over two periods (spring and autumn). We tested the probability of infection and differences in the parasite community in relation to the management model (releases vs. non releases) and sampling period, comparing autumn (when farm-reared birds are released) and spring (after hunting season, when mostly wild birds can be found in the population). We found a high prevalence (54%) of Plasmodium spp., and substantial differences in the spatial and temporal distribution of parasite lineages among the populations studied. Some parasite lineages occurred at high frequencies in game estates without introduction of farm-reared partridges, while other lineages were more abundant in game estates with releases than in those without releases. Overall, the prevalence of avian malaria was similar between spring and autumn at non-release sites, whereas in sites with releases, it was higher in autumn than in spring—probably due to artificial restocking with infected farm-reared birds at the onset of the hunting season. In short, humans may be an important agent driving the alteration of the spatial structure of local parasite fauna via the introduction of exotic parasites by gamebird release, which could cause avian malaria outbreaks with severe repercussions for native avifauna. [ABSTRACT FROM AUTHOR]