Bold or shy? Examining the risk-taking behavior and neophobia of invasive and non-invasive house sparrows

Bold or shy? Examining the risk-taking behavior and neophobia of invasive and non-invasive house sparrows. Behavior provides a useful framework for understanding specialization, with animal personality aiding our understanding of the invasiveness of birds. Invasions imply dispersion into unknown areas and could require changes in behavior or spatial clustering based on personality. Reduced neophobia and increased exploring behavior could allow individuals to colonize new areas as they test and use non-familiar resources. Here, we hypothesized that house sparrow (Passer domesticus) individuals from invasive populations would exhibit bolder behavior than in non-invasive populations. We assessed risk taking and neophobia in male house sparrows in Barcelona (where it is considered native) and in Mexico City (where it has become widely invasive), captured in two different habitats, urban and non-urban. We assessed latency to enter an experimental cage and to explore it, and latency to feed and feeding time in the presence of a novel object. We found that sparrows from Mexico City, both from urban and non-urban areas, were quicker to enter the experimental cage than the sparrows from Barcelona. The time it took the birds to start exploring the cage gave a similar result. We found no differences between cities or habitats in the latency to feed and feeding time while exposed to a novel object. Our results partially support the view that the invader populations from Mexico City are bolder than those from Barcelona. Behavior is an important component of plasticity and its variability may have an important effect on adaptation to local situations. Future studies should disentangle the underlying mechanisms that explain the different personalities found in populations of different regions, contrasting populations of different densities, and taking different food availability scenarios into account.Peer reviewe

Stress responses of the House Sparrow ( Passer domesticus) to different urban land uses

Urbanization generates human-made habitats with novel resources. Such change is not homegeneous, and includes different urban land uses characterized by specific habitat traits. In this study we explored the ecophysiologial response of an urban-exploiter species in three different urban land uses (urban, suburban, industrial). Our results show that corticosterone (obtained through fecal samples) and immunoglobulin (obtained through blood samples) concentrations did not differ significantly among the studied urban land uses. Corticosterone and immunoglobulin concentration showed both high and low values in urban and suburban areas, while industrial areas had low and high levels of corticosterone, and medium-to-low immunoglobulin concentration values. Also, we found a negative relationship between corticosterone and immunoglobulin concentrations in industrial areas. Based on corticosterone and immunoglobulin concentration thresholds established from previous studies, our results suggest that: (1) birds in the three studied urban conditions are both stressed and non-stressed; and (2) the immune system of industrial House Sparrows could not be responding successfully to pathogens. Not finding physiological relationships in urban and suburban areas underline that this species has a large capacity to respond to the different stress and immune challenges found in urban areas. However, our results suggest that the physiological condition of industrial House Sparrows could be compromised by differences in the frequency and intensity of the stressor agents faced by the birds in this land use category

Superciliums in white-eared hummingbirds as badges of status 2 signaling dominance

The role of badges as indicators of contest ability has been previously described. In hummingbirds, the exhibition of a badge is expected to save energy expenditure in agonistic interactions and to favor energy intake. Here, we investigate whether variable supercilium size in the white-eared hummingbird has a role in dominance status signaling. Firstly, 45 hummingbird males were captured and their superciliums were photographed to investigate variation in size and any possible allometric relationships. Secondly, 42 male birds were used to analyze whether the supercilium has a role in dominance status signaling in a dyadic contest. We found that supercilium size varied continuously but that despite variability between individuals, there was no relationship between supercilium size and body size. However, our dyad experiment indicated that birds with larger badges were able to make more visits to the feeders than individuals with smaller badges. We suggest a status signaling function of the supercilium.The role of badges as indicators of contest ability has been previously described. In hummingbirds, the exhibition of a badge is expected to save energy expenditure in agonistic interactions and to favor energy intake. Here, we investigate whether variable supercilium size in the white-eared hummingbird has a role in dominance status signaling. Firstly, 45 hummingbird males were captured and their superciliums were photographed to investigate variation in size and any possible allometric relationships. Secondly, 42 male birds were used to analyze whether the supercilium has a role in dominance status signaling in a dyadic contest. We found that supercilium size varied continuously but that despite variability between individuals, there was no relationship between supercilium size and body size. However, our dyad experiment indicated that birds with larger badges were able to make more visits to the feeders than individuals with smaller badges. We suggest a status signaling function of the supercilium.The role of badges as indicators of contest ability has been previously described. In hummingbirds, the exhibition of a badge is expected to save energy expenditure in agonistic interactions and to favor energy intake. Here, we investigate whether variable supercilium size in the white-eared hummingbird has a role in dominance status signaling. Firstly, 45 hummingbird males were captured and their superciliums were photographed to investigate variation in size and any possible allometric relationships. Secondly, 42 male birds were used to analyze whether the supercilium has a role in dominance status signaling in a dyadic contest. We found that supercilium size varied continuously but that despite variability between individuals, there was no relationship between supercilium size and body size. However, our dyad experiment indicated that birds with larger badges were able to make more visits to the feeders than individuals with smaller badges. We suggest a status signaling function of the supercilium

Bold or shy? Examining the risk-taking behavior and neophobia of invasive and non-invasive house sparrows

Dado que el comportamiento proporciona un marco útil para comprender la especialización, la personalidad animal puede ayudar a explicar la capacidad invasiva de las aves. La invasión implica la dispersión por áreas desconocidas y podría requerir cambios en el comportamiento o agrupaciones espaciales basadas en la personalidad. La reducción de la neofobia y el aumento del comportamiento de exploración podrían permitir a los individuos colonizar nuevas áreas a medida que prueban y utilizan recursos que no les son familiares. En este trabajo suponemos que los individuos de gorrión común (Passer domesticus) mostrarán un comportamiento más audaz en las poblaciones invasivas que en las poblaciones no invasivas. En este estudio evaluamos la toma de riesgo y la neofobia en machos de gorrión común de Barcelona (donde se considera nativo) y de Ciudad de México (donde es invasivo) capturados en dos hábitats diferentes (urbano y no urbano). Evaluamos la latencia para entrar en la jaula experimental y para explorarla, así como la latencia para alimentarse y el tiempo de alimentación en presencia de un objeto extraño. Encontramos que los gorriones de Ciudad de México, tanto de hábitats urbanos como no urbanos, entraron más rápido en la jaula experimental que los gorriones de Barcelona. El resultado fue similar para el tiempo que les tomó comenzar a explorar la jaula. No encontramos diferencias entre ciudades y hábitats en cuanto a la latencia para alimentarse y el tiempo que les tomó alimentarse en presencia de un objeto extraño. Nuestros resultados apoyan parcialmente la idea de que las poblaciones invasivas de Ciudad de México son más atrevidas que las de Barcelona. El comportamiento es un componente importante de la plasticidad y su variabilidad puede tener un efecto importante en la adaptación a situaciones locales. Se deberían llevar a cabo otros estudios para desentrañar los mecanismos que explican las diferencias de personalidad que se encuentran entre poblaciones de distintos orígenes, así como comparando poblaciones con diferente densidad demográfica y teniendo en cuenta diferentes contextos de disponibilidad de alimentos.Behavior provides a useful framework for understanding specialization, with animal personality aiding our understanding of the invasiveness of birds. Invasions imply dispersion into unknown areas and could require changes in behavior or spatial clustering based on personality. Reduced neophobia and increased exploring behavior could allow individuals to colonize new areas as they test and use non–familiar resources. Here, we hypothesized that house sparrow (Passer domesticus) individuals from invasive populations would exhibit bolder behavior than in non–invasive populations. We assessed risk taking and neophobia in male house sparrows in Barcelona (where it is considered native) and in Mexico City (where it has become widely invasive), captured in two different habitats, urban and non–urban. We assessed latency to enter an experimental cage and to explore it, and latency to feed and feeding time in the presence of a novel object. We found that sparrows from Mexico City, both from urban and non–urban areas, were quicker to enter the experimental cage than the sparrows from Barcelona. The time it took the birds to start exploring the cage gave a similar result. We found no differences between cities or habitats in the latency to feed and feeding time while exposed to a novel object. Our results partially support the view that the invader populations from Mexico City are bolder than those from Barcelona. Behavior is an important component of plasticity and its variability may have an important effect on adaptation to local situations. Future studies should disentangle the underlying mechanisms that explain the different personalities found in populations of different regions, contrasting populations of different densities, and taking different food availability scenarios into account