Behavioural responses to human disturbance in an alpine bird

Vallino, Cristina; Caprio, Enrico; Genco, Fabrizio; Chamberlain, Dan; Palestrini, Claudia; Roggero, Angela; Bocca, Massimo; Rolando, Antonio

doi:10.1007/s10336-019-01660-z

Cited by 9 publications

(14 citation statements)

References 35 publications

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“…MA and C had numerically different Alpine Chough populations. A maximum flock size of 180 individuals was observed at C in 2017 (Vallino et al 2019). At the same site, Rolando et al (2003) recorded up to 300 individuals in the 1990s.…”

Section: Discussionmentioning

confidence: 88%

“…Observations were made daily, changing the time of day each site was observed to account for possible daily variations in behaviour. For each observation, we recorded flock size and site elevation (for more details see Vallino et al 2019). Particular individuals could not be distinguished since most birds were unmarked.…”

Section: Yellow-billed Chough Surveymentioning

confidence: 99%

“…Indeed, Alpine Choughs seem to prioritize group bonds over foraging success, with flocks formed by young individuals and adult females staying together with adult males (which have access to food first) even when food is scarce and not sufficient to feed every component of the flock (Delestrade 1999). Moreover, the potential benefit gained from feeding in big flocks is doubtful, since the number of items ingested increases in relation to the number of birds forming the group (Rolando et al 1997, Vallino et al 2019), but the time spent in the foraging patch decreases (Rolando et al 1997). Therefore, other than prey abundance distribution, sociality may also affect the selection of the foraging patch and influence flock size.…”

Section: Flock Size and Grasshopper Abundancementioning

confidence: 99%

“…Previous research carried out in these very same areas has documented other aspects of human impacts on flocks. Tourist presence in summer has been shown to directly disturb foraging behaviour, by reducing both feeding rates and the time spent in patches (Vallino et al 2019). The urbanization at C has significantly changed the ranging behaviour in winter, when birds stay in the town all day, roosting on buildings and occasionally feeding on scraps, whereas other populations in the Aosta valley display circadian migration movements, flying in flocks towards snow free valley bottoms to look for food in the morning, and coming back to the roosts in high elevation cliffs (often above 3000 m asl) in the afternoon (Rolando et al 2003).…”

Section: Flock Size and Grasshopper Biomassmentioning

confidence: 99%

“…However, studies on food web components and/or on trends in different groups joined by trophic links are scarce. Indeed, studies focussing on the distribution and trends of alpine species (Chamberlain et al 2012), and relationships between predators and prey in humanimpacted high elevation areas, have been severely neglected so far (Vallino et al 2019). The Yellow-billed (Alpine) Chough, Pyrrhocorax graculus, a gregarious bird that moves in flocks throughout the year, is an excellent target species in this context.…”

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confidence: 99%

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Flocking of Foraging Yellow-Billed Choughs Pyrrhocorax Graculus Reflects the Availability of Grasshoppers and the Extent of Human Influence in High Elevation Ecosystems

Vallino

Caprio

Genco

et al. 2020

Ardeola

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Mountain ecosystems are subject to many pressures, including changes in land use, rising temperatures and increasing recreational activities. These factors may disrupt food webs, threatening the survival of organisms and, ultimately, ecosystem functioning. However, few studies focus on the trends of different groups joined by trophic links in alpine ecosystems. The Yellow-billed (Alpine) Chough, Pyrrhocorax graculus, a gregarious bird that moves in flocks, is an ideal target species within this framework since it has a grasshopper-based diet during the summer and may inhabit sites that are heavily developed for recreational activities. We tested therefore whether flock size co-varied with grasshopper abundance along an elevational gradient in two alpine areas subject to different levels of human disturbance. Chough flock size and grasshopper abundance were measured along elevational transects. The median flock size was analysed in relation to grasshopper abundance and biomass, also performing negative binomial GLMs account for effects of period (i.e. from June to mid-August), site and elevation. In both study areas, chough flocks were larger at the elevation where grasshoppers were more abundant. This may indicate the capacity of the species to follow large scale fluctuations in their key insect prey. On the other hand, the relationship between flock size and grasshopper biomass was positive at a natural site and negative at a tourist site. This suggests that where there is a high level of human pressure, other factors, such as the availability of human-provided food, may disturb the natural relationship between choughs and their key prey. Overall, our results indicate that flocking by foraging Yellow-billed Choughs reflects both grasshopper abundance and the degree of anthropogenic influence. Messerli 2001;Brambilla et al. 2016).The study of high elevation food webs in this transforming environment is particularly urgent because any change in trophic interactions between organisms may affect organism survival and, ultimately, ecosystem functioning. Climate change, for instance, can affect trophic relations through the phenological mismatch that reduce the food supply for breeding birds (Flousek et al. 2015;Thackeray et al. 2016). However, studies on food web components and/or on trends in different groups joined by trophic links are scarce. Indeed, studies focussing on the distribution and trends of alpine species (Chamberlain et al. 2012), and relationships between predators and prey in humanimpacted high elevation areas, have been severely neglected so far (Vallino et al. 2019). The Yellow-billed (Alpine) Chough, Pyrrhocorax graculus, a gregarious bird that moves in flocks throughout the year, is an excellent target species in this context. It is generally assumed that flocking may be advantageous to detect predators (Rolando et al. 2001;Jiménez et al. 2013), and has additional survival value in relation to food finding (Ward and Zahavi 1973), for instance through sharing information about food localisation (F...

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Section: Discussionmentioning

confidence: 88%

Section: Yellow-billed Chough Surveymentioning

confidence: 99%