Impact of Shiny Cowbird and botfly parasitism on the reproductive success of the globally endangered Yellow Cardinal Gubernatrix cristata (original) (raw)
Related papers
Botfly Parasitism Effects on Nestling Growth and Mortality of Red-Crested Cardinals
The Wilson Journal of Ornithology, 2011
We collected observational data in three consecutive breeding seasons to study interactions between the botfly Philornis seguyi and Red-crested Cardinals (Paroaria coronata) in a temperate zone near the southern limit of Philornis distribution. We analyzed: (1) seasonal trends in prevalence of parasitism, (2) influence of botfly parasitism on nestling growth rate and survival, and (3) the association between nest site vegetation at different scales (i.e., nest tree, vegetation surrounding the nest tree, and landscape) and probability of botfly parasitism. Prevalence of parasitism was 28% and was higher later in the breeding season. Botfly parasitism produced sub-lethal (lower growth rate of nestlings that survive) and lethal (lower nestling survival) effects. The lethal effect was negatively associated with age at the time nestlings were parasitized. Botfly parasitism was not associated with vegetation characteristics at the level of nesting tree or vegetation surrounding the nesting tree, but was associated with landscape features. Parasite prevalence was higher in large continuous woodland patches than in small isolated patches. However, we did not observe increased use of isolated patches of forest by Red-crested Cardinals, suggesting that use of nest sites with high botfly parasite intensity could be the consequence of high host density.
RBO - Breeding biology of Yellow Cardinal Gubernatrix cristata in Brazil v3 CSF
The Yellow Cardinal, Gubernatrix cristata, has a small geographic range in Brazil, Uruguay, and Argentina. We studied the natural history of the only known Brazilian population of this endangered species (~50 individuals), which is socially monogamous and may breed cooperatively. During two breeding seasons (October to February of 2013-2015), we monitored nests and described the main breeding traits. The breeding season started from the first week of October, with a peak of active nests in mid-November and lasted until mid-February. We found 32 nests, of which 30 were monitored. Female built the open-cup nests in six days (n=1). All nests were built on Prosopis trees, on average at 2.4 m from the ground. Modal clutch size was three eggs (n=19), and female incubated for 13 days on average (n=7). Hatching rate was 76% and nestlings fledged after 16 days (n=6). Nestling survival rate was 67% with mean productivity of 1.6 fledglings/successful nest. Shiny Cowbird, Molothrus bonariensis, parasitized nests of the Yellow Cardinal, with a frequency of 67% and intensity of 1.9 egg per parasitized nest (1-4 eggs; n = 13). Parasitism in nestlings by botfly larvae (Philornis sp.) occurred in 33% of nests with nestlings. Nest predation was the main cause of nest losses (73%) and we recorded a Geoffroy's Cat, Leopardus geoffroyi, preying on a nest with eggs. The probability of success using the Program MARK was 13%. Fledgling survival rate during the first month outside the nest was 62% (8/13 fledglings). We found a longer breeding season, occurrence of second broods, and higher rates but fewer nest losses due to brood parasitism in comparison to the Formatted: English (United States) 2 Argentinian population. We highlight the importance of natural history studies for the conservation of different populations of the same species.
Breeding biology of the endangered Yellow Cardinal Gubernatrix cristata in Brazil
Revista Brasileira de Ornitologia, 2019
The Yellow Cardinal, Gubernatrix cristata, has a small geographic range in Brazil, Uruguay, and Argentina. We studied the natural history of the only known Brazilian population of this “Endangered” species (∼50 individuals), which is socially monogamous and may breed cooperatively. During two breeding seasons (October to February 2013–2015), we monitored nests and described the main breeding traits. The breeding season started from the first week of October, with a peak of active nests in mid-November and lasted until mid-February. We found 32 nests, of which 30 were monitored. Female built the open-cup nests in six days (n = 1). All nests were built on Prosopis trees, on average at 2.4 m from the ground. Modal clutch size was three eggs (n = 19), and female incubated for 13 days on average (n = 7). Hatching rate was 76% and nestlings fledged after 16 days (n = 6). Nestling survival rate was 67% with mean productivity of 1.6 fledglings/successful nest. Shiny Cowbird, Molothrus bonar...
The main cause of nest mortality for most bird species is predation and nest survival rates often vary in relation to time-specific variables. Few investigators have examined time-specific patterns of nest survival in Neotropical birds, and most such studies have focused on tropical and subtropical species. To better understand age-related patterns of nest survival, we studied nest survival of Red-crested Cardinals (Paroaria coronata, Thraupidae) in a south-temperate forest in Argentina. We modeled daily nest survival rates (DSR) using program MARK. We examined the relationship between nest age and nest survival rate, controlling for the effects of physical characteristics of nest sites and progression of the breeding season. We monitored 367 nests for a total of 4018 exposure days. We found that DSR increased with nest age and was higher in small isolated patches than in large continuous patches of forests. The increase of DSR with nest age could be a consequence of more vulnerable nests being predated early in the nesting cycle or a result of parents defending nests more vigorously as nestlings age because of their increasing reproductive value. Open areas of grassland that surrounded the small isolated patches of forests in our study may have been a barrier to predator movements, possibly explaining the lower predation rates. Nest survival rates in our study were lower than those reported for tropical or Nearctic temperate birds, but similar to those reported in other studies of Neotropical temperate birds. Reasons for the low nest survival rates of Neotropical temperate birds remain unclear, and additional studies of predator communities are needed to help elucidate this topic.
Journal of Tropical …, 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 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.
Studies on breeding biology in Neotropical birds are crucial for understanding different aspects of their life histories and also for their conservation. We describe the nesting biology of the Red-crested Cardinal (Paroaria coronata) in central Argentina, a common suboscine inhabiting south temperate forests. We monitored 367 nests from October to February 2005-2008. Nest initiation followed a unimodal distribution with a peak in November. Within the forest, no nests were built on exotic tree species. Mean clutch size was 3.05 ± 0.05 eggs and decreased with time within the breeding season, but egg size did not vary throughout the breeding season. Nesting cycles lasted, on average, 25.8 ± 0.1 days (nest construction: 6.1 ± 0.4 days; incubation period: 11.9 ± 0.1 days; nestling period: 13.8 ± 0.1 days). At least one young fledged in 26% of nests, 62% were predated and 11% were abandoned. Egg survival rate was 0.95 ± 0.02, hatching success rate was 0.84 ± 0.02, and nestling survival rate was 0.81 ± 0.03. Partial nestling losses were detected in 45% of the nests, of which 52% were due to brood reduction. Each breeding pair had on average 4.4 ± 0.2 nesting attempts over the breeding season. Our results support the prediction that small clutch sizes are associated with extensive breeding seasons and several nesting attempts within a season. Except for the short incubation period, all other breeding features reported in this study differ from those of most north temperate birds and are consistent with the life history traits of Neotropical birds.
Red-crested cardinal defences against shiny cowbird parasitism
Avian brood parasites reduce the reproductive success of the host, which favours the evolution of antiparasitic defences, such as aggression towards parasites or rejection of their eggs. The red-crested cardinal, Paroaria coronata, is a potential good-quality host of the shiny cowbird, Molothrus bonariensis. However, the frequency of cowbird parasitism in cardinal nests is very low and there are no records of this host raising parasite's chicks, which suggest that it may have evolved effective antiparasitic defences. We studied cardinal antiparasitic defences by: (1) presenting dummy models of a female cowbird and non-predator and predator control species to nests during laying and incubation, and (2) conducting experiments of artificial parasitism with natural cowbird eggs of different morphs and conspecific eggs during laying and early and late incubation. We found that: (1) the frequency of cowbird parasitism in cardinal nests was 7%, (2) cardinals did not exhibit aggressive behaviours towards cowbird or nonpredator models but responded aggressively towards a predator model, (3) they rejected parasite eggs in 98.5% of the cases (mostly through egg ejection), but conspecific eggs in only 6% of the cases, (4) there were no costs (breakage or ejection of their own eggs) associated with ejection of the parasite's eggs, and (5) a relatively low frequency of parasitism is enough selection pressure to maintain egg rejection at a high level. The antagonistic expression of antiparasitic defences in red-crested cardinals suggests that they may have lost the behaviour of aggression towards the parasite as a result of associated costs.
Auk, 2003
Shiny Cowbirds (Molothrus bonariensis) oft en parasitize larger hosts. It has been proposed that larger hosts are preferred by that parasite because they provide higher reproductive success, but available data are quite variable. We studied the reproductive success of Shiny Cowbirds in nests of Brown-and-yellow Marshbirds (Pseudoleistes virescens), a larger and oft en multiply parasitized host. To estimate the extent of interspecifi c competition, we compared the hatching success of parasite eggs in nests with and without reduction of the clutch size of the host as a result of egg punctures infl icted by the parasite, and the survival and growth of parasite chicks reared with and without host chicks. To estimate the extent of intraspecifi c competition, we compared Shiny Cowbird egg losses, hatching success, and chick survival in singly versus multiply parasitized nests. Reproductive success of Shiny Cowbirds was 8% with depredation causing 80% of losses. Clutch reduction due to egg punctures were higher in multiply than in singly parasitized nests, but it did not improve hatching success of parasite eggs. Neither survival nor growth of parasite chicks was aff ected by the presence of host chicks. Shiny Cowbird hatching success and chick survival did not diff er between singly and multiply parasitized nests. Parasite chicks were smaller than same-age Brown-and-yellow Marshbird chicks. However, because parasite chicks hatched one or two days before host chicks and had a higher growth rate, they were the larger chicks in the nest. Overall Shiny Cowbird reproductive success in Brown-and-yellow Marshbird nests was apparently higher than that reported in other smaller or similar-sized hosts. We think that host life-history traits like large clutch size, a longer incubation period, and slower growth rate of chicks are responsible for the high reproductive success of Shiny Cowbirds with Brown-and-yellow Marshbirds.
Bird Conservation International, 2020
SummaryThe Yellow Cardinal Gubernatrix cristata is a globally endangered passerine from the southern cone of South America. Because of its conspicuous plumage and very attractive song, it suffers considerably from illegal pet trade. The largest remaining populations are found in Argentina, but no coordinated efforts have been made thus far to understand better its current distribution and conservation status. During three annual surveys supported by a citizen science programme, more than 140 volunteers surveyed 644 geographical points during spring and detected 221 Yellow Cardinals. Based on the survey results, we evaluated the presence of cardinals within protected areas in Argentina and found that the species was only detected in four of them, two of which were private reserves with a low level of protection. We also found that the species was not restricted to the ‘Espinal’ ecoregion, but also inhabited ‘Monte’ and ‘Chaco’ ecoregions, which are generally drier. This citizen scien...