Papers by Rodrigo Vasquez
Background: Many studies have attempted to link variation in corticosterone (Cort), the primary g... more Background: Many studies have attempted to link variation in corticosterone (Cort), the primary glucocorticoid (GC) in birds, with reproductive output, however the consequences of variation in Cort levels on survival probability have been relatively less explored. When considering baseline Cort and survival probability, two hypotheses have been proposed, the cort-fitness hypothesis and the cortactivity hypothesis. Notwithstanding a few exceptions, studies have generally however shown no relationship between levels of baseline Cort and the probability of survival. Methods: With the aim of increasing our understanding of the effect of baseline Cort on survival probability we utilized mark-recapture data from a long-term study (eight years of capture-markrecapture) of the Thorn-tailed Rayadito ( Aphrastura spinicauda ), fitting different survival models with and without baseline Cort levels as covariates. Secondly, because the two populations in our study have different values of baseline Cort, we evaluated whether the association between baseline Cort and apparent inter-annual survival probability varied in relation to these two populations. Results: In the high latitude population (the population with lower baseline Cort levels), we observed a quadratic (inverted U-shape) relationship between baseline Cort levels and inter-annual survival probability; in the low latitude population, baseline Cort had no apparent effect on inter-annual survival probability. Conclusions: Because of the quadratic relationship, a relationship that only can be observed with long-term data, our approach emphasizes the importance of using a capture-recapture model. In addition, because the effect of baseline Cort on survival probability was found to be contextdependent, our work also highlights the importance of comparing different populations.
Seasonal modulation of the adrenocortical stress responses in Chilean populations of Zonotrichia capensis
Journal of ornithology, Sep 1, 2018
AbstractTo persist in a landscape, organisms are often faced with evolutionary tradeoffs between ... more AbstractTo persist in a landscape, organisms are often faced with evolutionary tradeoffs between individual survival and reproduction. In environments where breeding opportunities are brief, it has been hypothesized that individuals will decrease investments in self-preservation in favor of reproductive success. Many avian species in the Northern Hemisphere have been shown to diminish their physiological response to perturbations of the environment by decreasing the adrenocortical response to acute stress during the parental care phase of reproduction. We present results from three populations of Rufous-collared Sparrow (Zonotrichia capensis) in the Southern Hemisphere in which we compared the dynamics of changes in plasma levels of corticosterone after capture, handling and restraint in pre-breeding and nesting phases. The results suggest that the degree of seasonal reduction of the adrenocortical stress response in parental birds is different from that of congeners in the Northern Hemisphere. Males of all three populations of Z. capensis in our study attenuated the adrenocortical stress response equally between the early breeding and parental sub-phases of nesting despite breeding at very different altitudes and latitudes. In contrast, females from all three populations showed no seasonal attenuation of the adrenocortical stress response over the seasons examined in this study. These findings suggest that further comparative investigations are needed to compare Northern Hemisphere-based endocrine patterns in different, global contexts.ZusammenfassungSaisonale Modulation der adrenokortikalen Reaktion auf Stress in chilenischen Populationen vonZonotrichia capensis Um in einer Landschaft bestehen zu können, müssen Organismen häufig evolutionäre Kompromisse zwischen ihrem eigenen Überleben und ihrer Fortpflanzung eingehen. Es wurde die Hypothese aufgestellt, dass in einer Umwelt, in der Brutmöglichkeiten knapp sind, Individuen zu Gunsten ihres Reproduktionserfolges die Investition in ihre eigene Selbsterhaltung reduzieren. Es konnte für viele Vogelarten der nördlichen Hemisphäre nachgewiesen werden, dass sie ihre physiologische Reaktion auf Umweltstörungen durch eine Herabsenkung der adrenokortikalen Reaktion auf Stress während der Zeit der elterlichen Fürsorge vermindern. Wir präsentieren hier Ergebnisse für drei Populationen der Morgenammer (Zonotrichia capensis) der südlichen Hemisphäre, für die während der Vorbrut-und Nistzeit die Veränderungsdynamik des Corticosteronspiegels im Plasma nach dem jeweiligen Fang und dem Handling des Vogels verglichen wurden. Die Ergebnisse lassen vermuten, dass der Grad der saisonalen Reduktion der adrenokortikalen Reaktion auf Stress in Elternvögeln unterschiedlich zu dem der Artgenossen der nördlichen Hemisphäre ist. In unserer Studie verminderten die Männchen aller drei Populationen von Z. capensis gleichermaßen die adrenokortikale Reaktion zwischen der frühen Brutphase und den Teilphasen der elterlichen Fürsorge während der Nistzeit, unabhängig von der Lage der Bruten in unterschiedlichen Höhen-und Breitengraden. Im Gegenteil dazu zeigte keines der Weibchen der drei Populationen während des Untersuchungszeitraumes eine saisonale Verringerung der adrenokortikalen Reaktion. Diese Ergebnisse deuten darauf hin, dass weitere Studien nötig sind, um die auf der nördlichen Hemisphäre basierenden endokrinen Muster in verschiedenen globalen Kontexten zu vergleichen.
Journal of Heredity, Oct 1, 2020
Heterozygosity-fitness correlations (HFCs) have been used to monitor the effects of inbreeding in... more Heterozygosity-fitness correlations (HFCs) have been used to monitor the effects of inbreeding in threatened populations. HFCs can also be useful to investigate the potential effects of inbreeding in isolated relict populations of long-term persistence and to better understand the role of inbreeding and outbreeding as drivers of changes in genetic diversity. We studied a continental island population of thorn-tailed rayadito (Aphrastura spinicauda) inhabiting the relict forest of Fray Jorge National Park, north-central Chile. This population has experienced a long-term, gradual process of isolation since the end of the Tertiary. Using 10 years of field data in combination with molecular techniques, we tested for HFCs to assess the importance of inbreeding depression. If inbreeding depression is important, we predict a positive relationship between individual heterozygosity and fitness-related traits. We genotyped 183 individuals at 12 polymorphic microsatellite loci and used 7 measures of reproductive success and estimates of apparent survival to calculate HFCs. We found weak to moderate statistical support (P-values between 0.05 and 0.01) for a linear effect of female multi-locus heterozygosity (MLH) on clutch size and nonlinear effects on laying date and fledging success. While more heterozygous females laid smaller clutches, nonlinear effects indicated that females with intermediate values of MLH started laying earlier and had higher fledging success. We found no evidence for effects of MLH on annual fecundity or on apparent survival. Our results along with the long-term demographic stability of the study population contradict the hypothesis that inbreeding depression occurs in this population.
Conservation Physiology, 2018
Repeated exposure to traffic noise may be perceived as a succession of stressors, and therefore, ... more Repeated exposure to traffic noise may be perceived as a succession of stressors, and therefore, noisy urban environments could lead to a state of chronic stress. In developing animals, glucocorticoids can have organizational effects on the hypothalamic-pituitary-adrenal axis in addition to the classic activation effects, so evaluating the effect of traffic noise during development is urgently needed. To our knowledge, to date six studies have investigated the effects of traffic noise on baseline corticosterone (CORT) and/or the stress response in birds during development; however, these studies were performed in nestling (altricial species), where confounding factors (e.g. communication between nestlings and parents) could mask the real impact of traffic noise on stress. In this study, we evaluated the effect of traffic noise (traffic noise group vs. rural noise group) on baseline levels of CORT and stress responses in chicks of a precocial bird species, the Japanese quail (Coturni...
Risk‐taking behaviour relates to timing of breeding in a sub‐Antarctic rainforest bird
Ibis, Mar 5, 2021
Within‐population variation in timing of breeding may be linked to a trade‐off between the risks ... more Within‐population variation in timing of breeding may be linked to a trade‐off between the risks and benefits of breeding earlier. This trade‐off may be mediated by individual risk‐taking behaviour, but this needs to be assessed in detail in wild populations. Here, we recorded timing of breeding and risk‐taking behaviour during three consecutive breeding seasons in a resident population of Thorn‐tailed Rayadito Aphrastura spinicauda located in Navarino Island (55°S), southern Chile. Navarino is a high‐latitude, highly seasonal continental island in southern Chile where early breeding may be risky for rayaditos, given the presence of low temperatures, storms and relatively low food abundance during early spring. We used novel environment tests to assess exploratory behaviour, which in turn was used as a proxy of risk‐taking behaviour. In addition, we evaluated the potential consequences of timing of breeding and risk‐taking behaviour on three measures of reproductive success: clutch size, number of fledglings produced and body condition of the offspring. We found that risk‐prone individuals started breeding earlier than risk‐averse individuals but we did not find evidence for an effect of timing of breeding on any of the variables of seasonal breeding success. However, we observed that fast‐exploring females tended to lay smaller clutches. Measurements reflecting lifetime reproductive success may better reflect an effect of timing of breeding and risk‐taking behaviour, but this needs to be studied. Our results support the idea that risk‐taking behaviour is linked to early breeding in high‐latitude environments. We suggest that, despite the risks that low temperatures and snowstorms pose to breeding rayaditos during early spring, it is possible that early breeders increase the probability of occupying better nesting cavities and they may adjust the timing of breeding to match brood provisioning with peak resource abundance.
Proceedings of The Royal Society B: Biological Sciences, Jan 22, 2000
It is well established that social conditions often modify foraging behaviour, but the theoretica... more It is well established that social conditions often modify foraging behaviour, but the theoretical interpretation of the changes produced is not straightforward. Changes may be due to alterations of the foraging currency (the mathematical expression that behaviour maximizes) and/or of the available resources. An example of the latter is when both solitary and social foragers maximize rates of gain over time, but competition alters the behaviour required to achieve this, as assumed by ideal free distribution models. Here we examine this problem using captive starlings Sturnus vulgaris. Subjects had access to two depleting patches that replenished whenever the alternative patch was visited. The theoretical ratemaximizing policy was the same across all treatments, and consisted of alternating between patches following a pattern that could be predicted using the marginal value theorem (MVT). There were three treatments that di¡ered in the contents of an aviary adjacent to one of the two patches (called the `social' patch). In the control treatment, the aviary was empty, in the social condition it contained a group of starlings, and in a non-speci¢c stimulus control it contained a group of zebra ¢nches. In the control condition both patches were used equally and behaviour was well predicted by the MVT. In the social condition, starlings foraged more slowly in the social than in the solitary patch. Further, foraging in the solitary patch was faster and in the social patch slower in the social condition than in the control condition. Although these changes are incompatible with overall rate maximization (gain rate decreased by about 24% by self-imposed changes), if the self-generated gain functions were used the MVT was a good predictor of patch exploitation under all conditions. We discuss the complexities of nesting optimal foraging models in more comprehensive theoretical accounts of behaviour integrating functional and mechanistic perspectives.
Vigilance and social foraging in Ocotodon degus (Rodentia: Octodontidae) in central Chile
Revista Chilena de Historia Natural, 1997
Author response for "The delayed effect of climatic conditions on pre‐fledging nestling haematocrit in a suboscine species in Patagonia
Journal of Avian Biology
Haematocrit, the proportion of blood comprising erythrocytes, is often used as a proxy of individ... more Haematocrit, the proportion of blood comprising erythrocytes, is often used as a proxy of individual condition. Nestling haematocrit is influenced by several factors but ambient temperature is generally agreed as a key driver. It is unclear which day(s) in embryonic or nestling development are most influential in determining pre-fledgling haematocrit. This is important, because if we are able to identify what day(s) nestlings are physiologically most vulnerable to climatic conditions, this may inform future conservation management and help mitigate the effects. We investigated the effect of ambient temperature, precipitation, body size, brood size, age, food abundance and habitat on nestling haematocrit in Aphrastura spinicauda (thorn-tailed rayaditos). We collected this data from two climatically different locations in Chile: northern Patagonia (Pucón) and Sub-Antarctic Patagonia (Navarino Island), located ~ 1800 km further south. We aimed to identify the key drivers of nestling haematocrit and find when nestlings are physiologically most vulnerable to climatic conditions. We confirm that ambient temperature is the key driver of nestling haematocrit, with increasing ambient temperatures nestling haematocrit decreased. However, precipitation also affected haematocrit in the late incubation stage. At low and high precipitation, nestling haematocrit was low and is optimum in light rainfall. Our results show a delayed effect of ambient temperature and precipitation in late incubation and on the day of hatching which can determine pre-fledgling haematocrit, which may cause lower post-fledgling fitness. We found that climatic conditions on the day haematocrit was collected was not important in determining haematocrit. We found that haematocrit was higher in the sub-Antarctic area and that higher temperatures and precipitation on the day of hatching will result in lower nestling haematocrit and poorer pre-fledgling condition. As atmospheric temperatures rise, nestling fitness is at risk. This is a threat to many bird species, especially those in locations vulnerable to climate breakdown.
Assessing the reproductive consequences of mate retention and pair bond duration in Thorn‐tailed Rayadito (Aphrastura spinicauda), a short‐lived, socially monogamous neotropical bird
Ibis
The adaptive value of mate retention has been studied in several socially monogamous birds but ev... more The adaptive value of mate retention has been studied in several socially monogamous birds but evidence of reproductive benefits for short‐lived species is inconclusive. Most studies come from northern latitudes but more research on tropical birds is needed, as these species typically show higher survival rates and longer pair bonds than those from temperate regions. We gathered data on the reproductive biology of a subtropical, isolated population of Thorn‐tailed Rayadito Aphrastura spinicaudaduring 2008–2017 to evaluate the reproductive consequences of mate retention. We examined data from 243 breeding attempts made by 159 breeding pairs. We found that ~30% of all breeding pairs bred together during at least two consecutive years, and some were mated for 6 years. The main cause of pair dissolution was mate loss, not divorce. Mixed‐effects models provided moderate evidence for positive effects of mate retention and successive remating on reproductive success. Newly formed pairs lai...
Influence of the haemosporidian Leucocytozoon spp. over reproductive output in a wild Neotropical passerine, the Thorn‐tailed Rayadito (Aphrastura spinicauda)
Ibis
Life‐history theory predicts that hosts may adjust the costs of parasites by altering their repro... more Life‐history theory predicts that hosts may adjust the costs of parasites by altering their reproductive effort. Haemosporidian parasites can affect the reproductive output of wild birds in multiple ways. Thorn‐tailed Rayaditos Aphrastura spinicauda breeding in Navarino Island, southern Chile (55°–40°S), experience a high prevalence of the haemosporidian Leucocytozoon spp., which opens the possibility of exploring how these parasites may affect reproductive output in a Neotropical bird species. We compared several variables describing reproductive output (laying date, clutch size, incubation period, brood size, nestling body condition and early‐life telomere length) of infected and non‐infected parents (individually and as breeding pairs). We found that infected females and breeding pairs with both parents infected showed significantly shorter incubation periods than un‐infected Thorn‐tailed Rayaditos. Furthermore, breeding pairs where both parents were infected raised nestlings wit...
Evidence of low within‐pair genetic relatedness in a relict population of Thorn‐tailed Rayadito despite long‐term isolation
Ecology and Evolution
Investigating whether mating patterns are biased in relation to kinship in isolated populations c... more Investigating whether mating patterns are biased in relation to kinship in isolated populations can provide a better understanding of the occurrence of inbreeding avoidance mechanisms in wild populations. Here, we report on the genetic relatedness (r) among breeding pairs in a relict population of Thorn‐tailed Rayadito (Aphrastura spinicauda) in north‐central Chile that has experienced a long‐term history of isolation. We used simulations based on 8 years of data to assess whether mating is random with respect to relatedness. We found that mean and median population values of pair relatedness tended to be lower than randomly generated values, suggesting that mating is not random with respect to kinship. We hypothesize that female‐biased dispersal is the main mechanism reducing the likelihood of mating among kin, and that the proportion of related pairs (i.e., r > 0.125) in the study population (25%) would presumably be higher in the absence of sex‐biased dispersal. The occurrence...
Data from: The extreme rainfall gradient of the Cape Horn Biosphere Reserve and its impact on forest bird richness. Biodiversity and Conservation
<strong>Description of dataset</strong> This dataset contains information about fores... more <strong>Description of dataset</strong> This dataset contains information about forest bird species richness and climatic variables in 61 sample sites of the Cape Horn Biosphere Reserve. This dataset was analysed in : Quilodrán CS, Sandvig EM, Aguirre F, Rivero de Aguilar J, Barroso O, Vásquez RA, and R Rozzi. 2022. Effects of the extreme rainfall gradient in the Cape Horn Biosphere Reserve on forest bird richness. <em>Biodiversity and Conservation</em>. <strong>Acknowledgments </strong> This study was funded by grants for Technological Centers of Excellence with Basal Financing of the National Agency for Research and Development (ANID-Chile), granted to the Cape Horn International Center (CHIC- FB210018) and the Institute of Ecology and Biodiversity (IEB-AFB170008). CSQ acknowledges support from the Swiss National Science Foundation (N°P5R5PB_203169).
A sentinel for monitoring climate change and its impact on biodiversity at the southern summit of the Americas: the new Cape Horn Long-Term Socio-Ecological Research Network
Anales del Instituto de la Patagonia; Vol. 48 Núm. 3 (2020); 45-81, Aug 17, 2021
Scientific collaboration with the Chilean Navy for long-term ornithological studies in the Diego Ramírez Archipelago: first year-round monitoring of Gonzalo Island’s bird assemblage
Anales del Instituto de la Patagonia; Vol. 48 Núm. 3 (2020); 149-168, Jan 26, 2021
Mobbing behaviour in non-breeding flocks of a passerine bird in northern Patagonia
Behaviour, 2022
Animal cooperation occurs in both genetically related and unrelated groups of individuals, involv... more Animal cooperation occurs in both genetically related and unrelated groups of individuals, involving costs and benefits that have not been fully elucidated. For example, risky behaviour such as mobbing a predator would be selected if participants are genetic relatives because they share a fraction of their gene pool (i.e., kin selection or indirect benefits). However, in the absence of genetic relatedness, benefits can be achieved by direct benefits such as reciprocity or mutualism, among others. In this study we analyzed the cooperative mobbing behaviour in winter flocks of an endemic passerine of the austral temperate forests, the Thorn-tailed rayadito (Aphrastura spinicauda). We first tested whether the probability of and the latency to mobbing response differed depending on the acoustic stimulus perceived by the flock (i.e., conspecific mobbing calls vs. predator calls), and whether the intensity of the mobbing was related to the number of individuals and species participating. ...
Heterozigosity-fitness correlations in a continental island population of Thorn-tailed Rayadito
Heterozygosity-fitness correlations (HFCs) have been used to monitor the effects of inbreeding in... more Heterozygosity-fitness correlations (HFCs) have been used to monitor the effects of inbreeding in threatened populations. HFCs can also be useful to investigate the potential effects of inbreeding in isolated relict populations of long-term persistence, and to better understand the role of inbreeding and outbreeding as drivers of changes in genetic diversity. We studied a continental island population of thorn-tailed rayadito (Aphrastura spinicauda) inhabiting the relict forest of Fray Jorge National Park, north-central Chile. This population has experienced a long-term, gradual process of isolation since the end of the Tertiary. Using 10 years of field data in combination with molecular techniques, we tested for HFCs to assess the importance of inbreeding depression. If inbreeding depression is important, we predict a positive relationship between individual heterozygosity and fitness-related traits. We genotyped 183 individuals at 12 polymorphic microsatellite loci, and used seven...
Risk‐taking behaviour relates to timing of breeding in a sub‐Antarctic rainforest bird
Ibis, 2021
Within‐population variation in timing of breeding may be linked to a trade‐off between the risks ... more Within‐population variation in timing of breeding may be linked to a trade‐off between the risks and benefits of breeding earlier. This trade‐off may be mediated by individual risk‐taking behaviour, but this needs to be assessed in detail in wild populations. Here, we recorded timing of breeding and risk‐taking behaviour during three consecutive breeding seasons in a resident population of Thorn‐tailed Rayadito Aphrastura spinicauda located in Navarino Island (55°S), southern Chile. Navarino is a high‐latitude, highly seasonal continental island in southern Chile where early breeding may be risky for rayaditos, given the presence of low temperatures, storms and relatively low food abundance during early spring. We used novel environment tests to assess exploratory behaviour, which in turn was used as a proxy of risk‐taking behaviour. In addition, we evaluated the potential consequences of timing of breeding and risk‐taking behaviour on three measures of reproductive success: clutch ...
Ecology and Evolution, 2021
Extra‐pair behavior is present in 76% of socially monogamous bird species with biparental care. T... more Extra‐pair behavior is present in 76% of socially monogamous bird species with biparental care. This behavior may produce costs to females related to a reduction in paternal care. We estimated the percentage of extra‐pair offspring and quantified paternal care in 44 nests of Thorn‐tailed Rayadito (Aphrastura spinicauda) to assess whether males reduce their parental care when females obtain extra‐pair fertilizations. We used data from a sub‐Antarctic population of Rayadito located on Navarino Island (55°4′S, 67°40′W), southern Chile. We found no statistical support for a relationship between variation in paternal care and the percentage of extra‐pair offspring. We discuss how the inability of breeding males to assess their genetic paternity and potential restrictions on behavioral flexibility may explain this result. Additionally, if paternal care is subjected to sexual selection, this could limit a facultative response to female extra‐pair behavior by males. Finally, it is possible ...
Behavioral Ecology and Sociobiology, 2017
In birds, the frequency with which the parents feed the young can vary considerably. Because of s... more In birds, the frequency with which the parents feed the young can vary considerably. Because of sexual differences in the begging behaviour and/or differences in the food requirements of the nestlings, brood sex ratio (BSR) is an important factor that may influence parental provisioning behaviour. Disparities in the quantity and quality of prey received by the sexes have been reported in a range of sexually size-dimorphic birds. However, to our knowledge, no study has evaluated prey composition delivery to nestlings in relation to BSR in a non-dimorphic size bird species. Because BSR influences provisioning rate in dimorphic and non-size dimorphic species and because in dimorphic species, BSR influences prey composition delivered to the nest, we hypothesised that similar to dimorphic species, BSR may influence prey composition delivered to nestlings in non-size dimorphic species. We quantify parental provisioning rate and prey compos
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Papers by Rodrigo Vasquez