Human Disturbance during Early Life Impairs Nestling Growth in Birds Inhabiting a Nature Recreation Area

Abstract

Nature recreation conflicts with conservation, but its impacts on wildlife are not fully understood. Where recreation is not regulated, visitors to natural areas may gather in large numbers on weekends and holidays. This may increase variance in fitness in wild populations, if individuals whose critical life cycle stages coincide with periods of high human disturbance are at a disadvantage. We studied nestling development of blue tits (Cyanistes caeruleus) in a natural area where recreation activities intensify during weekends and other public holidays at picnic and leisure facilities, but not in the surrounding woods. In nests located near recreation facilities, blue tit nestlings that hatched during holidays developed slowly, and fledged with low body mass and poor body condition. However, nestlings that hatched outside of holidays and weekends in these nest boxes developed normally, eventually attaining similar phenotypes as those hatching in the surrounding woods. Within-brood variance in body mass was also higher in broods that began growing during holidays in disturbed areas. Our results show that early disturbance events may have negative consequences for wild birds if they overlap with critical stages of development, unveiling otherwise cryptic impacts of human activities. These new findings may help managers better regulate nature recreation.

Humans and Tits in the City: Quantifying the Effects of Human Presence on Great Tit and Blue Tit Reproductive Trait Variation

“…In contrast with our findings, Remacha et al (2016) showed that blue tit nestlings from forested areas used as a recreational site that hatched on days with increased activity of visitors (weekends and other nonworking days) were found to grow slower and fledge with lower body mass; this difference may be due to differences in birds' environmental backgrounds: in a more semi-natural context, where human presence is higher during the breeding season, it is possible that birds are more sensitive to human disturbance. Birds inhabiting rural realities already showed a higher physiological and behavioural stress response than their urban counterparts, often revealed through a higher flightinitiation distance (McGiffin et al, 2013;Abolins-Abols et al, 2016).…”

“…However, human presence correlated with distance to paths only in the urban park, which may be caused by a larger detection power of such associations due to a larger number of visitors overall. Our results are thus in line with the findings of Remacha et al (2016), who reported that distance to paths is a reliable index of human disturbance. In the case of roads, there is no evidence that this infrastructure is correlated with distribution of human presence detected on the ground, thereby suggesting that the presence of such infrastructural facilities at the site level is not always an important source of human presence, although it can impact reproduction through independent means, as explained below.…”

“…These results suggest that behavioural responses are usually context-dependent and related to the trade-offs experienced by individuals: indeed, it is easier to expect habituation in birds that are used to human presence, which is a common scenario in an urban park, while birds in rural environments may react to human presence adversely (Remacha et al, 2016). Furthermore, the impact of human disturbance is likely to change among avian species or species with variable ecological niches: ground and shrub nesting birds, for example, are likely to be more sensitive to human disturbance.…”

“…It can depend on season and weather conditions (sunny vs. rainy days; Gladalski et al, 2016), days of the week (weekends vs. working days; Remacha et al, 2016) or hours of the day (morning peak hour vs. afternoon). It is thus important that such variability is taken into account when quantifying human presence and its possible disturbance to wildlife.…”

El impacto en las aves por el turismo de naturaleza: una mini revisión

“…El turismo de naturaleza parece afectar directa o indirectamente a gran cantidad de especies de fauna silvestre, incluidas las aves (Gill, 2007). Algunos estudios han determinado que los efectos negativos de estas actividades son generados inicialmente por la alteración o disturbio de sus ambientes (Remacha et al, 2016). Sin embargo también se ha sugerido que la presencia humana y el ruido generado por estas actividades pueden también afectar directamente aspectos fisiológicos y conductuales de la fauna (Steven, 2011;Lindsay et al, 2008).…”