Physiological and Behavioral Differences in Magellanic Penguin Chicks in Undisturbed and Tourist-Visited Locations of a Colony
(Impact Factor: 4.17).
10/2005; 19(5):1571-1577. DOI: 10.1111/j.1523-1739.2005.00104.x
Studies examining anthropogenic effects on wildlife typically focus on adults and on behavioral responses rather than the physiological consequences of human disturbances. Here we examined how Magellanic Penguin ( Spheniscus magellanicus) chicks living in either tourist-visited or undisturbed areas of a breeding colony were affected by human visitation by comparing the baseline and stress-induced levels of corticosterone during three periods of the breeding season. Newly hatched chicks in visited areas had higher corticosterone stress responses than newly hatched chicks in undisturbed areas (p =0.007), but baseline levels were similar (p =0.61). By 40–50 days of age and around fledging time, both visited and undisturbed chicks showed a robust corticosterone stress response to capture. Tourist-visited chicks did not flee when approached by humans, however, whereas undisturbed chicks fled significantly sooner (i.e., when approached no closer than 9 m; p < 0.0001). Although it is unknown whether Magellanic Penguin chicks raised in visited areas suffer negative consequences from the elevation of the corticosterone stress response at hatching, they do exhibit behavioral habituation to human contact by the time they are ready to fledge. Unlike adults living in tourist areas, however, fledging chicks in visited areas do not have a decreased stress response to capture and restraint. Our results show that the coupling of behavioral and physiological habituation in Magellanic Penguins is complex and life-history context may greatly affect the ability of wildlife to adapt to anthropogenic disturbances.
Resumen: Los estudios de los efectos antropogénicos sobre la vida silvestre se centran típicamente en adultos y en las respuestas conductuales en lugar de las consecuencias fisiológicas de las perturbaciones humanas. Aquí examinamos el efecto de la visita de humanos sobre pollos de pingüino (Spheniscus magellanicus) en áreas visitadas por turistas o no perturbadas mediante la comparación de los niveles, base e inducidos por estrés, de corticoesterona durante tres períodos de la temporada reproductiva. Los pollos recién eclosionados en áreas visitadas tuvieron mayor respuesta de la corticoesterona al estrés que los pollos recién eclosionados en áreas no perturbadas (p =0.007), pero los niveles básicos fueron similares (p =0.61). A los 40–50 días y en la etapa de volantón, los pollos visitados y no perturbados mostraron una marcada respuesta de la corticoesterona al estrés al ser capturados. Sin embargo, los pollos visitados por turistas no huyeron cuando se les acercaron humanos, mientras que los pollos no perturbados huyeron significativamente antes (i.e., acercamiento a más de 9 m; p < 0.0001). Aunque se desconoce si los pollos de pingüino criados en áreas visitadas sufren consecuencias negativas por la elevación de la corticosterona en respuesta al estrés al eclosionar, si presentan acostumbramiento conductual al contacto con humanos al momento que están listos para dejar el nido. Sin embargo, a diferencia de adultos que viven en áreas turísticas, los pollos volantones en las áreas visitadas no tienen una disminución en la respuesta al estrés cuando son capturados y sujetados. Nuestros resultados muestran la complejidad de la combinación del acostumbramiento conductual y fisiológico en Spheniscus magellanicus y que el contexto de la historia de vida puede afectar a la habilidad de la vida silvestre para adaptarse a las perturbaciones antropogénicas.
Available from: Alexandre Roulin
- "Frequent anthropogenic disturbance can cause chronic stress (e.g. Fowler 1999; Müllner et al. 2004; Walker et al. 2005) and that chronic stress can decrease baseline corticosterone as shown in previous studies in the wild and in captivity (Rich and Romero 2005; Cyr et al. 2007; Cyr and Romero 2007) and might be a sign of desensitisation of the HPA axis to a certain chronic stressor (Cyr and Romero 2009). The increased acute corticosterone response of nestlings living close to humans shows, on the other hand, that these nestlings are not habituated to anthropogenic disturbance (Cyr and Romero 2009). "
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ABSTRACT: Human activities can have a suite of positive and negative effects on animals and thus can affect various life history parameters. Human presence and agricultural practice can be perceived as stressors to which animals react with the secretion of glucocorticoids. The acute short-term secretion of glucocorticoids is considered beneficial and helps an animal to redirect energy and behaviour to cope with a critical situation. However, a long-term increase of glucocorticoids can impair e.g. growth and immune functions. We investigated how nestling barn owls (Tyto alba) are affected by the surrounding landscape and by human activities around their nest sites. We studied these effects on two response levels: (a) the physiological level of the hypothalamus-pituitary-adrenal axis, represented by baseline concentrations of corticosterone and the concentration attained by a standardized stressor; (b) fitness parameters: growth of the nestlings and breeding performance. Nestlings growing up in intensively cultivated areas showed increased baseline corticosterone levels late in the season and had an increased corticosterone release after a stressful event, while their body mass was decreased. Nestlings experiencing frequent anthropogenic disturbance had elevated baseline corticosterone levels, an increased corticosterone stress response and a lower body mass. Finally, breeding performance was better in structurally more diverse landscapes. In conclusion, anthropogenic disturbance affects offspring quality rather than quantity, whereas agricultural practices affect both life history traits.
Available from: Marcelo Bertellotti
- "compared the seasonal variation in baseline (first sample after capture) and total corticosterone levels over the restraint period. We calculated total corticosterone levels using the arithmetic trapezoid rule, which calculates the area under the corticosterone stress response curve for each penguin (Walker et al. 2005). We log transformed baseline corticosterone levels because of lack of normality, and ran an analysis of variance (ANOVA) for baseline and total corticosterone levels with stage (incubation , early chick, late chick, or molt) as the main factor. "
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ABSTRACT: Penguin colonies are highly visited world-wide. While several studies have addressed how penguins behaviorally respond to tourist visitation at one point in time, nothing is known about their response across the entire breeding season. Furthermore, behavioral responses are driven by complex physiological and the basal physiological state of the individual might affect the way they respond to stimuli. To test the hypothesis that annual changes in corticosterone result from animals having different requirements for expressing (or not) the glucocorticoid-mediated behaviors at different times of the year in the context of tourist visitation, we examined circulating and stress-induced corticosterone in Magellanic penguins from non-visited areas (Spheniscus magellanicus) from San Lorenzo colony, Peninsula Valdes, Argentina across the breeding season. We also examined the behavioral responses of penguins to a pedestrian approach in tourist-visited and non-visited areas of the colony across the season. Our results showed that circulating levels of corticosterone did not varied across the season, however stress-induced corticosterone was lowest during molt. Our behavioral results showed that penguins displayed different occurrence of behavior responses at varying distances depending on the area and stage in the season. Penguins in the tourist area were more tolerant to a human approach than penguins in the non-tourist area. During settlement and molt penguins showed higher occurrence of behaviors related to self-survival (such as standing, go further into the nest and fleeing), while during incubation and chick rearing penguins displayed mostly a behavior associated to defense and vigilance (such as alternate head turns). Furthermore, penguins allowed a closer approach during incubation, but elicited a subsequent behavior quicker than in the rest of the stages, suggesting that they would be particularly sensitive in this period. Overall, our results suggest that corticosterone release across the season would be more associated to penguins’ survival in an extreme environment than to a behavioral regulation. From a conservation perspective, we identified that penguins were more sensitive during incubation, but also molt should be considered as a vulnerable period since corticosterone secretion is suppressed.
Available from: Hrefna Sigurjónsdóttir
- "leading to physiological responses, such as higher heart rate (MacArthur et al., 1982; Carney and Sydeman, 1999) and hormonal effects (Creel et al., 2002; Walker et al., 2005; Barja et al., 2007). Further, disturbance can cause animals to change their natural behaviour. "
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ABSTRACT: The effect of land-based seal watching on the haul-out pattern of harbour seals (Phoca vitulina) was investigated between June and August of 2008-2010 on Vatnsnes, NW Iceland. The results showed that the behaviour and spatial haul-out pattern of seals was affected by the tourists. In 2009 the seals were more likely to be vigilant during periods when tourists had access to the area, compared to a period when tourists were not allowed in the area. Also, in 2010 the likeliness of the seals being vigilant increased as the number of tourists in the area increased. In addition, seals were more likely to be vigilant when tourists behaved in an active way. During the post weaning period, which coincided with the peak of the tourist season, a significantly higher proportion of seals hauled out on the skerry located farthest away from land, compared to a skerry closer to land. Seals also preferred to haul out further away from land when the number of tourists in the area increased. Single tourists and couples behaved more passively compared to families and tourist groups of more than two adults. All tourist group types were significantly more active in an approaching zone than in the seal watching zone. Education of tourists, for example through a code of conduct built on these results, is advisable to minimise disturbance of seals in the area.
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