Human activities are the main current driver of global change. From hunter-gatherers through to Neolithic societies-and particularly in contemporary industrialised countries-humans have (voluntarily or involuntarily) provided other animals with food, often with a high spatio-temporal predictability. Nowadays, as much as 30-40% of all food produced in Earth is wasted. We argue here that predictable anthropogenic food subsidies (PAFS) provided historically by humans to animals has shaped many communities and ecosystems as we see them nowadays. PAFS improve individual fitness triggering population increases of opportunistic species, which may affect communities, food webs and ecosystems by altering processes such as competition, predator-prey interactions and nutrient transfer between biotopes and ecosystems. We also show that PAFS decrease temporal population variability, increase resilience of opportunistic species and reduce community diversity. Recent environmental policies, such as the regulation of dumps or the ban of fishing discards, constitute natural experiments that should improve our understanding of the role of food supply in a range of ecological and evolutionary processes at the ecosystem level. Comparison of subsidised and non-subsidised ecosystems can help predict changes in diversity and the related ecosystem services that have suffered the impact of other global change agents.

We studied the organization and temporal stability of an assemblage of malaria parasites (genera Plasmodium and Haemoproteus) and their passerine avian hosts in a forested study area in southern Missouri, USA, over four years. We detected parasite infections by polymerase chain reaction (PCR) of parasite DNA from host blood samples and identified parasite lineages by sequencing a part of the mitochondrial cytochrome b gene. We obtained 757 blood samples from 42 host species. Prevalence of malaria parasitism judged by PCR averaged 38.6% and varied in parallel in the three most abundant host species over the four years of the study. Parasite prevalence bore a U‐shaped relationship to host sample size. Prevalence was weakly positively associated with host body mass, but not with foraging stratum, nest height, nest type, plumage brightness, or sexual dichromatism. Over the sample as a whole, parasite prevalence did not vary between males and females or between hatch‐year and older individuals. We differentiated 34 parasite lineages. The number of host species per lineage varied from one to eight and increased with sample size. We recovered up to 14 lineages of parasite from a single host. Three relatively common lineages in the Ozarks were found nowhere else; four others were recovered from other sites in eastern North America; and six additional well‐sampled lineages were distributed in the Greater Antilles among resident island host species. Parasites that are endemic among native species of hosts on the tropical wintering grounds of Ozark birds were recovered from hatch‐year birds in the Ozarks, indicating that transmission takes place on the summer breeding grounds, and consequently, that suitable vectors are present in both the temperate and tropical portions of the parasite lineage distributions. We estimate that the number of parasite lineages within a local area will approximate the number of host species and that our perception of host breadth and parasite diversity will increase for most lineages and hosts with increased sampling. Thus, host–parasite relationships in a local area, including the role of parasites in sexual selection and the evolutionary maintenance of sex, are likely to be complex, with population and evolutionary dynamics involving many actors.

Few studies have addressed the effects of food availability as a proximate factor affecting local adult survival in long-lived organisms and their consequences at local population dynamics. We used capturerecapture analysis of resightings of 10 birth cohorts of ringed Audouin's gulls, Larus audouinii, to estimate adult survival and dispersal (both emigration and immigration). For the first time, permanent emigration (the transient effect in capture-recapture analysis) was modelled for the whole population and not only for the newly marked birds. Gulls exploit to a large extent fishes discarded from trawlers, and a trawling moratorium established since 1991 has decreased food supply for the colony. This was used as a natural experiment of food availability to assess its effects on adult survival and emigration. These and other demographic parameters were used in a projection modelling to assess the probabilities of extinction of the colony under two scenarios of lower and higher food availability. Food availability (together with the age of individuals) influenced emigration probabilities, but not adult survival, which was estimated at 0.91 (s.e. = 0.02). When food was in shorter supply during the chick-rearing period, emigration was very high (ca. 65%) for younger breeders, although this rate decreased sharply with age. Probabilities of extinction were very high when food availability was low, and when environmental stochasticity was introduced, and only stochastic immigration from the outside seemed to prevent extinction. The results highlight the importance of dispersal processes in the population dynamics of long-lived organisms.

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Owing to increasing population trends and facultative predatory habits, large gulls have been identified as significant agents of change in the alteration of many ecological communities. Often, they are perceived as negatively impacting the population trends of most sympatric waterbirds. Consequently, culling programs have been implemented to remove adults, chicks and eggs intensively. Here, we review the interactions recorded in the literature between the yellow-legged gull Larus michahellis and 10 sympatric waterbirds in the Mediterranean region, all threatened and classified as species of conservation concern. We also used 177 long-term population trends derived from previous studies to study the population dynamics of these species and the culling effort performed. We show that gulls negatively affected survival, fecundity, foraging ecology and nesting habitat availability for many species. However, the annual population growth rates of most sympatric waterbirds showed positive values, even at sites where culling has yet to be initiated and local yellow-legged gull populations are large and increasing. Our results suggest clearly that population increase has not been exclusive of yellow-legged gulls, especially at the regional level. Yet, growth rates of both yellow-legged gulls and sympatric waterbirds were positively associated. Strikingly, the population extinction rate was similar between colonies of yellowlegged gulls and those of sympatric species. Thus, evidence exists to state that the success of gull control programs is relatively low in the long term. We recommend that conservation agencies heed several basic principles of population and community ecology before initiating control, for instance that (1) yellow-legged gulls have bred historically with other bird species and have likely developed defensive mechanisms against this predator and (2) populations of large gulls are regulated by density-dependent mechanisms in both space and time. Incoming European environmental policies on fishing discards and rubbish management should control more naturally and efficiently the density of large gulls and the composition of seabird communities in the long term.

Summary 1.Wind farms are emerging as a major cause of mortality of large scavenging bird species, which may be catastrophic when they operate in concert with other threats. As a study model, we examine the impact of wind turbines on the population dynamics of a soaring bird species, when acting in conjunction with a sudden decrease in food availability following the European bovine spongiform encephalopathy (BSE) epidemic. 2. In Spain, vultures have been provided with supplementary food at traditional vulture restaurants for centuries. In 2006 ⁄ 2007, these feeding stations were closed as part of disease control measures. At the same time, wind farms were deployed within the vulture foraging range. We used capturerecapture data and direct observation to monitor the impacts of these changes on the vulture population. 3. The number of breeding pairs decreased by c. 24%, adult survival by 30% and fecundity by 35%. However, the population recovered as soon as the perturbations ceased, the vulture restaurants were reopened, and the most problematic wind turbines were closed. Population recovery was faster than predicted by a retrospective stochastic population model. 4. Our analyses indicate that fecundity and survival were influenced predominantly by wind turbines. Food scarcity promoted a shift in foraging behaviour that drove vultures to fly into the path of wind turbines as they sought out new food sources in a landfill site. Elasticity and sensitivity analyses of the population model showed that mortality of adult birds had a much greater effect on population declines than mortality of immature birds, whereas reduction in fecundity had negligible effects. 5. The most likely explanation for the rapid recovery of the vulture population is that the observed decline in breeding pairs was not solely because of increased mortality. The decline probably included dispersal away from the area and a greater incidence of skipped breeding during the perturbation years. Subsequent immigration from large nearby populations was probably a factor in population recovery. 6. Synthesis and applications. Where specific wind turbines are causing substantial mortality, their closure is an effective management response. For vulture populations dependent on supplemental feeding stations, the feeding sites should be relocated away from the most problematic wind turbines, or other anthropogenic sources of mortality, to prevent negative impacts. We recommend the establishment of scattered, low-value food sources to replicate historical conditions and to avoid the problems associated with high concentrations of individuals in one place.