Integrative assessment of immunity, health-state, growth and survival of Magellanic penguin chicks in a colony exposed to ecotourism.

Accumulating reports of negative impacts of tourist activities on wildlife emphasize the importance of closely monitoring focal populations. Although some effects are readily noticed, more subtle ones such as changes in physiological functions of individuals might go overlooked. Based on evidence of altered physiology associated with ecotourism on Magellanic penguins Spheniscus magellanicus, here we performed an integrated assessment using a diverse physiological toolkit together with more traditional fitness-related measures to better understand mechanisms and potential consequences. Chicks exposed to tourism showed altered immune parameters and elevated flea prevalence, reinforcing previous findings. Tourism-exposed female, but not male, chicks also showed relatively lower hematocrit and plasma protein levels, providing evidence consistent with a sex-specific response to tourist visitation. Physiological alterations detected in tourism-exposed young chicks (week 1-2) were maintained and the effect on flea infestation increased during the study period (week 4-5 of post-hatch). Despite the effects on physiology, these did not seem to translate into immediate fitness costs. No detectable tourism effects were found on brood sex ratios, chick growth and body condition, and survival until week 5-6 post-hatch. We detected no effects on reproductive output and only a marginal effect on nest survival during incubation despite previous reports of tourism-associated alterations in stress indices of adults. This disconnection could result if the physiological changes are not strong enough to impact fitness, if effects balance each other out, or if changes are part of a copying strategy. Alternatively, the physiological alterations might only show impacts later in the brooding cycle or even after chick emancipation from their parents. Our results suggest that integrative monitoring of potential anthropogenic impacts on wildlife should include evaluation of physiological mechanisms and individual-level responses in populations exposed to human activities.

Offspring body condition and immunocompetence are negatively affected by high breeding densities in a colonial seabird: a multiscale approach.

Why avian colonies vary in size and how food competition among nearby colonies affects offspring quality are still not completely understood. We simultaneously examined the effects of four scales of breeding density on two measures of offspring viability (body condition and T-cell-mediated immunity) in the colonial Magellanic penguin. Body condition of fledglings was inversely correlated with breeding density within 100 m(2) of nests, and decreased with increasing numbers of breeding pairs competing within the parental foraging ranges (100 km), probably as a result of density-dependent food depletion. The T-cell-mediated immune response was positively correlated with body condition, reflecting, to some extent, the previous breeding-density effects, and was negatively correlated with colony size, which may be related to social stress. However, given the effect of protein intake on cell immunity, this result could also indicate a thus far neglected cost of coloniality, namely the consumption of low-protein food to compensate for the depletion of optimal prey. These results were not influenced by other traits, nor by the current exposure of birds to parasites and diseases, as measured by serological variables. Since body condition and the T-cell-mediated immune response of fledgling birds are indicators of their survival and recruitment prospects, the costs we have identified can explain variability in colony size in relation to food competition with surrounding colonies, as well as the skewed distribution toward small colonies in this species.

Effects of spatial and host variables on hematozoa in white-crowned sparrows wintering in Baja California.

A survey of blood parasites was conducted in February 1995 on white-crowned sparrows (Zonotrichia leucophrys) wintering in two environmentally different localities of Baja California Sur (Mexico). Blood parasite prevalence was higher in La Purísima (49%) than in San José del Cabo (8%), but there were no differences between ages or sexes within each locality. All haematozoa infections were by Haemoproteus coatneyi, except one bird in each site that were positive for Trypanosoma sp. We found no evidence for the predicted negative relationship between host body condition and intensity of parasitism. The relatively high prevalence in one site suggests that an increase of hematozoa transmission may occur in that area.