Scavenging is ubiquitous in nature, but its implications have rarely been investigated. We used camera traps on wolf kills to investigate the role of scavenging on predator and multiprey dynamics in a northern Apennine system in Italy. In contrast to North American systems, the omnivorous wild boar successfully competes with wolves for the meat of their kills. We developed a deterministic, multitrophic web model (wolf, vegetation, deer, and wild boar), tunable through a parameter that governs the impact of prey sharing between wolves and wild boar. When prey sharing is scarce, populations oscillate, but above a threshold value the trophic web is stabilized, with the regime solution becoming a fixed, stable point. Both deer and wild boar then increase as a function of prey sharing, and the impact of herbivores on the vegetation increases. When prey sharing exceeds another threshold, the system collapses due to the extinction of both wolves and wild boar. Our analysis shows that scavenging is crucial for the dynamics of this ecosystem, and thus it should not be overlooked in food web modeling. The exploitation of wolf kills by wild boar may allow juveniles and yearlings to obtain high-quality resources that are not usually available, helping the wild boar to compensate for losses caused by hunting. This is likely to make them even more invasive and difficult to control.
Introduction: Compensation programs are an important tool for mitigating conflicts between farmers and large predators. However, they present significant weaknesses and faults. For years, the EU has been prioritizing programs for the prevention of damage caused by large carnivores, rather than compensation programs, introducing compulsory compensation for the purposes of decision EC (2019) 772 of 29/01/19. This manuscript reports the experience with the wolf damage prevention programs in an Italian region, Emilia-Romagna, which implemented a pilot project, adopting a new method to interface with the farmers involved in the prevention programs. Methods: Starting in 2014, a project aimed at spreading prevention measures was financed through regional and European resources, accompanied by resources sharing and technical assistance with breeders from the regional body. In detail, (i) standardized types of intervention were defined and technical assistance was structured; (ii) ex post, the effectiveness of the interventions carried out was assessed; and (iii) the difficulties encountered in using the various financing instruments were analyzed. Results: Overall, 298 farms were analyzed, of which 166 applied for regional calls and 132 applied for European funds. The mitigation measures produced a reduction in predatory phenomena of 93.4%, i.e., from 528 to 35 predations over a period of 4–6 years. This study shows that more than one-third of the farmers were forced to abandon the two tenders, mainly due to the lack of liquidity in anticipating the prevention measures. Conclusion: In the years examined by this study, the prevention programs in the Emilia-Romagna region, due to the technical support offered, proved to be a functional and effective tool, capable of significantly reducing the wolf predation on livestock. However, this work highlights the high percentage of denials of mitigation measures by farmers interested in adopting these tools, stressing the need for regional agencies to focus on new policies that can provide advance economic resources to farmers and solve the authorization problems related to the various bodies with which the participant in the tenders must interface.
English - The gray wolf (Canis lupus) expanded its distribution in Europe over the last few decades. To better understand the extent to which wolves could re-occupy their historical range, nowadays including anthropized landscapes, it is important to test if and how anthropization can affect fitness-related traits in this species. We modeled how anthropization was associated with the body condition of 175 wolves that were found dead in Italy between 1999 and 2021. After having accounted for ecologically-relevant confounders, we assessed how anthropization influenced i) the growth of wolves in their first year of age (n = 53), ii) sexual dimorphism between male and female adult wolves (n = 121). Wolves in anthropized areas grow up more slowly during their first year of age. This because young wolves have slightly higher body weight at 3-5 months, possibly due to the availability of human-derived food sources, but not a higher weight later. The difference in the body weight of adult females and males slightly increases with anthropization. However, this because of an increase in the body mass of males only, possibly due to sex-specific differences in dispersal and/or to “dispersal phenotypes”. Anthropization in Italy does not seem to have any clear, nor large, effect on the body mass of young and adult wolves. To the best of our knowledge, this is the first time that a similar effect is reported for a large carnivore. Our findings indicates that wolves could potentially re-occupy most of their historical range in Europe, as anthropized landscapes do not seem to constrain their body mass, an important trait related to their fitness. Wolf management could therefore be needed across vast spatial scales and in anthropized areas prone to social conflicts. Italiano - Il lupo (Canis lupus) è una specie che, nel corso degli ultimi decenni, ha aumentato la propria diffusione in Europa. Per capire meglio se e quanto essa potrebbe occupare nuovamente il proprio areale di distribuzione storico, che oggi include anche paesaggi antropizzati, è importante quantificare se, e quanto, il grado di antropizzazione dell'ambiente ne condizioni alcuni tratti biologici associati alla fitness. In questo studio è stata modellata l’associazione tra l’antropizzazione e la condizione corporea di 175 lupi che sono stati rivenuti morti in Italia, tra il 1999 ed il 2021. In particolare, dopo avere condizionato le analisi ad un set di fattori confondenti potenzialmente rilevanti dal punto di vista ecologico, è stata quantificata l’influenza del grado di antropizzazione dell’ambiente: i) sulla crescita degl individui di lupo durante il primo anno di vita (n = 53), ii) sul dimorfismo sessuale tra maschi e femmine adulti (n = 121). I lupi provenienti da ambienti maggiormente antropizzati sembrano avere un accrescimento più lento durante il primo anno di vita. Questo perché essi hanno un peso corporeo leggermente più alto a 3-5 mesi di età, forse per via della maggiore disponibilità di risorse trofiche di origine umana, ma non un maggiore peso corporeo nei mesi successivi. La differenza nel peso corporeo delle femmine e dei maschi adulti sembra incrementare leggermente con il grado di antropizzazione dell’ambiente. Tuttavia, questo aumento è legato soltanto ad un aumento nel peso corporeo dei maschi, forse a causa di differenze tra maschi e femmine nei processi di dispersione e/o alla presenza di “fenotipi da dispersione”. In Italia,il grado di antropizzazione dell’ambiente non sembra quindi avere nessun effetto chiaro, o importante, sul peso corporeo dei lupi. Né su quello dei giovani, durante primo anno di età, né su quello degli adulti. Per quanto ne sappiamo, questo è il primo studio che rileva l’assenza di un effetto del grado di antropizzazione dell'ambiente su di un grande carnivoro. Implicazioni pratiche. I risultati di questo studio indicano che il lupo potrebbe potenzialmente ri-occupare la maggior parte del proprio areale di distribuzione storico in Europa. Questo in virtù del fatto che il grado di antropizzazione dell’ambiente non sembra condizionarne il peso corporeo, un importante parametro biologico fortemente associato alla fitness. In questo caso, eventuali strategie di gestione della specie andrebbero quindi implementate su grosse scale spaziali, anche in aree antropizzate, dove il rischio di conflitti sociali sul tema è maggiore.
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