The wild boar Sus scrofa as a threat to ground‐nesting bird species: an artificial nest experiment

Abstract

Nest predation is reported as a cause of reproductive failure of ground‐nesting bird species whose populations in Europe are declining. Conversely, European populations of the wild boar Sus scrofa have been expanding, leading to increasing threats to habitats and ecological communities. The impacts of wild boar on ground‐nesting bird species are poorly known and have never been explicitly assessed. We conducted an artificial ground‐nest experiment in Mediterranean habitats of central Italy using camera traps to assess predator identities. Deployed nests contained quail or chicken eggs, and predation occurred within one week for 47/48 deployments carried out during March‐July 2020. The wild boar was the most common predator (36% deployments), followed by the magpie Pica pica (18%), the red fox Vulpes vulpes (10%) and the pine marten Martes martes (10%). Predation by other species was occasionally observed. Egg type and deployment habitat did not significantly influence time to predation or the likelihood that a nest was preyed upon by wild boar, respectively. The presence of a stuffed gull close to the nests significantly delayed predation. Nests preyed by birds and mammals other than wild boar were often subsequently scavenged by wild boar, which consumed the remaining eggs or eggshells. Time to predation increased from spring to summer, suggesting a reduction of predation intensity during periods when the availability of natural eggs is lowest. The likelihood of a nest being preyed upon by the wild boar compared to other predators increased when wild boar frequency of occurrence in 1‐week camera trap shootings was the highest, suggesting that higher abundance/activity of this species triggered increased egg predation. The wild boar might act as major predators of ground‐nesting bird species in Mediterranean habitats and the large‐scale population increase of this ungulate should be considered a significant threat to ground‐nesting species of European conservation concern.

Carried away by a moonlight shadow: activity of wild boar in relation to nocturnal light intensity

“…In line with its perceptive capabilities, previous studies highlighted that wild boar nocturnal movements are mostly concentrated during brightest nights or crepuscular hours, when environmental visibility is the highest (Brivio et al 2017;Colino-Rabanal et al 2018). However, wild boar food search is mostly based on the sense of smell (Ollivier et al 2004;Morelle et al 2015;Mori et al 2021b), allowing this species to range also when environmental visibility is at its lowest (Schlageter and Haag-Wackernagel 2012). Finally, as the model including the actual environmental brightness works better than the models describing moon cycle, we can argue that nocturnal activity cycle is only weakly related to moon cycle.…”

“…1 (cf. Mori et al 2021b;Viviano et al 2021). Three brooks and some ponds fed by rainfall are present.…”

Recent Invaders in Small Mediterranean Islands: Wild Boars Impact Snakes in Port-Cros National Park

“…After 2016, and only on the island affected by wild boars, did we find a significant decline in snake counts, recruitment, and annual population growth rates in both species. These results provide further evidence that wild boars can be destructive when they proliferate, notably in the absence of predatory pressures (wolf or hunters) [14,[47][48][49].…”

Do ditch‐side electric fences improve the breeding productivity of ground‐nesting waders?

“…The suite of nest predators includes many mammals and birds, posing a risk for nests night and day. Nest and chick predators in Europe are primarily mammals, including badger Meles meles , stoat Mustela erminea , polecat Mustela putorius , American mink Mustela vison , wild boar S us scrofa , racoon dog Nyctereutes procyonoides and red fox Vulpes vulpes , and to a lesser extent birds, including carrion crow Corvus corone , marsh harrier Circus aeruginosus , blue heron Ardea cinerea and buzzard Buteo buteo (Madden et al., 2015; Mori et al., 2021; Nordström et al., 2003; Roos et al., 2018; Salewski & Schmidt, 2020; Salewski et al., 2019; Teunissen et al., 2008). High densities and expanding distributions of predators, predation‐compromised conservation efforts, high levels of philopatry of breeding waders (Kruk et al., 1998; Thompson & Hale, 1989; Thompson et al., 1994) and limited suitable habitat all constrain the ability of waders to relocate to alternative areas with a lower predation risk.…”