Evidence for tolerance of parasitism in a tropical cavity-nesting bird, planalto woodcreeper (< i> Dendrocolaptes platyrostris), in northern Argentina (original) (raw)
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Journal of Tropical Ecology, 2010
Avian hosts may either resist the negative effects of nestling ectoparasites by minimizing the number of parasites, or tolerate parasitism by increasing their fecundity via the reproductive compensation hypothesis. Little is known about the interactions between ectoparasites and their avian hosts in the tropics. We (1) examined nestling development rates, and tested whether (2) parasitism by a subcutaneous ectoparasitic botfly (Philornis sp.) had negative effects on the condition of nestlings, and (3) these negative effects were minimized in larger broods in a tropical cavitynesting bird, the planalto woodcreeper (Dendrocolaptes platyrostris), in primary and secondary Atlantic forests in the northern province of Misiones, Argentina. Nestling mass and ectoparasite load per nestling reached maxima when nestlings (n = 50) were between 10 and 14 d old. General linear mixed models predicted that mass at fledging declined with increasing nestling parasite load, suggesting that botflies had a negative influence on fledging condition. Parasite load per nestling declined with increasing brood size indicating that woodcreepers that increase their reproductive output minimize the negative effects of parasitism. Overall we found evidence to support the tolerance via reproductive compensation hypothesis. Future tests of the reproductive compensation hypothesis may help determine the underlying mechanism of the observed negative correlation between parasite load of nestlings and brood size.
Journal of ornithology, 2023
In the Galapagos Islands, many endemic landbird populations are declining due to habitat degradation, food availability, introduced species and other factors. Given nestlings typically lack efficient defense mechanisms against parasites, hematophagous ectoparasites such as the larvae of the introduced Avian Vampire Fly, Philornis downsi, can impose high brood mortality and cause threatening population declines in Darwin finches and other landbirds. Here, we assess whether the food compensation hypothesis (i.e., the parents' potential to compensate for deleterious parasite effects via increased food provisioning) applies to the Green Warbler-Finch. We differentiated nests with low or high infestation levels by P. downsi and quantified food provisioning rates of male and female parents, time females spent brooding nestlings, and nestling growth. Male provisioning rates, total provisioning rates and female brooding time did not significantly vary in relation to infestation levels, nor by the number of nestlings. Opposed to the predictions of the food compensation hypothesis, females showed significantly reduced provisioning rates at high infestation levels. Nestling body mass was significantly lower and there was a reduction of skeletal growth, although not significantly, in highly infested nests. The females' response to high infestation may be due to parasites directly attacking and weakening brooding females, or else that females actively reduce current reproductive effort in favor of future reproduction. This life-history trade-off may be typical for Darwin finches and many tropical birds with long lifespans and therefore high residual reproductive value. Conservation strategies may not build on the potential for parental food compensation by this species. Keywords Nest parasite • Parental care • Nestling growth • Host defense • Galapagos Islands • Philornis downsi Zusammenfassung Elterliche Nahrungsversorgung und Nestlingswachstum beim durch die IUCN als "gefährdet " eingestuften Waldsänger-Darwinfink bei Befall durch die parasitische invasive Vampirfliege Philornis downsi Auf den Galapagos-Inseln sind auf Grund von Habitatstörungen, eingeschleppten und invasiven Organismen und anderen Faktoren viele Vogelarten und Populationen in ihrer Existenz bedroht. Beispielsweise führen die hämatophagen Larven der eingeführten Vampirfliege Philornis downsi zu einer hohen Brutsterblichkeit unter den endemischen Darwinfinken, insbesondere da bei Nestlingen die Immunabwehr noch schwach und unvollständig ausgeprägt ist. Hier wird untersucht, ob brütende Waldsänger-Darwinfinken Certhidea olivacea in der Lage sind, die für das Nestlingswachstum schädlichen Communicated by F. Bairlein. Heinz Richner and Sabine Tebbich: Shared last authorship.
Ardeola, 2015
We studied the parasitism of the exotic European starling Sturnus vulgaris by native botflies Philornis spp. in Argentina. We installed thirty nest boxes in the northeastern Buenos Aires province in the 2010-2011 breeding season. In the first brood, subcutaneous larvae of Philornis (Muscidae) parasitised 34 nestlings (89.4%) of 11 clutches (91.6%) and only three nestlings fledged. In the second brood, Philornis parasitised 15 (48.3%) nestlings of seven clutches (70%) and all the nestlings died. Compared to the mortality of other Neotropical birds parasitised by Philornis, the mortality in European starling nests is the highest found in the region. Our results show that the studied population of European starling suffers a high level of parasitism by Philornis, although this factor was not directly associated with the high mortality of starling nestlings. The fact that most non-parasitised nestlings also died indicates that other factors are also affecting nestling survival. Experiments that allow us to isolate the effect of Philornis from other variables would be needed to evaluate the impact of botfly larvae on starling nestlings.
Native parasitic nest fly impacts reproductive success of an island‐endemic host
Animal Conservation
Parasitic nest flies Philornis spp. are a driving force threatening the extinction of bird species endemic to Neotropical islands such as the Galapagos, where introduced Philornis downsi negatively impacts reproductive success of naive avian hosts. Elsewhere in the Neotropics, such as in the Caribbean region where Philornis nest flies are native, effects of Philornis on host productivity are poorly known. We manipulated parasitism by the native Hispaniolan nest fly Philornis pici on a critically endangered endemic host, Ridgway's hawk Buteo ridgwayi, to study the impact of nest fly myiasis on hawk breeding success with the goal of providing a management option for endangered species until broad‐scale solutions can be found. Our treatment protocol was enough to reduce P. pici abundance by 89% and increase probability of fledging by 179% for treated nestlings. Our results indicate that parasitism by nest flies decreases survival and fledging success of nestling Ridgway's hawks and is a possible factor in the decline of the species. To the best of our knowledge, this work represents the first quantitative evidence of nest fly impact on survival or productivity in a non‐passerine host.
The Journal of Caribbean Ornithology, 2018
Abstract: This study presents details of the reproductive biology of the Puerto Rican Emerald (Chlorostilbon maugaeus) and the first detailed record of its interactions with botfly (Philornis sp.) parasites. The data and observations are based on a nest found on 15 April 2015 in the Luquillo Experimental Forest, Luquillo, Puerto Rico. I monitored the nest and the behavior of the female parent for 29 days, beginning 5 days prior to egg-laying and continuing until the nestlings were found dead in the nest. Incubation lasted 15–17 days and the nestlings died 5–7 days after hatching. A photograph taken 2 days before the nestlings were found dead revealed the presence of subcutaneous botfly larvae, suggesting the parasites may have contributed to their deaths. This case is among the first recorded instances of botfly parasitism of a hummingbird in the Antilles. I compare these findings and other behavioral observations to known natural history of the Puerto Rican Emerald and other hummin...
Oecologia, 1993
Parasites are usually assumed to negatively affect fitness components of their hosts, particularly during adverse environmental conditions. We experimentally tested whether the ectoparasitic house martin bug (Oeciacus hirundinis) had larger negative effects on its house martin (Delichon urbica) host during second clutches. Conditions for reproduction decreased during the season, being less favourable for the second clutch than the first clutch. This was demonstrated by smaller clutch sizes, lower breeding success and smaller and lighter nestlings during the second clutch, as compared to the first, in the absence of parasites. Experimental manipulation of the intensity of parasitism resulted in the reproductive success of the host being reduced with increasing numbers of house martin bugs. This effect was much stronger during the second, as compared to the first, clutch. The house martin bug therefore had a greater detrimental effect on the reproduction of its host when conditions for reproduction were poor.