Birds were housed in individual cages height: Tests started after a 2-day habituation period during which the birds were fed ad libitum.
City bird, country bird – Aesop's fable revisited (Video) | TreeHugger
On the day of the first behavioral test, birds were food-deprived overnight for 14h. Behavioral tests began at 9: Birds were then fed ad libitum until the next overnight deprivation starting at Birds were given a commercial mix of finch seeds when fed before and between the tests and also as a reward for behavioral tests. During the tests, the observer J. Birds lost on average 0. At the end of the captivity period 7 days , birds were released at their initial site of capture. Three out of the 53 birds died from unknown causes during captivity testing 1 female from White Hill, 1 female from Swans, and 1 male from Bellairs ; they were excluded from analyses.
Tests were always given in the same order to reduce the potential biases emerging from habituation see Ducatez, Audet, et al.
Behavioral tests started on day 3 of captivity with boldness assessment. Birds were presented with an open Petri dish full of seeds same dish and food as during the habituation period , and the experimenter hid behind the curtain until the bird had fed all birds fed within 12min. The same procedure was repeated on the 3 following days of captivity to assess repeatability of the boldness measure.
On day 3, after the boldness test, neophobia was assessed by presenting a novel object beside the Petri dish until the bird fed or reached the maximum min limit of the trial, in which case this min latency was recorded for the individual. Neophobia was measured as the latency to feed, minus the mean latency of pre-control previous boldness measurement and post-control additional boldness measurement.
The first novel object was a cm yellow stake Supplementary Figure S2A.
To estimate repeatability of neophobia, we took another measure of neophobia on day 6, after changing the novel object to 2 brightly colored and textured balls dog toys, mm diameter placed directly on each side of the dish Supplementary Figure S2B. As our measure of neophobia, we used the mean of the neophobia latencies obtained on days 3 and 6. There was no significant difference between neophobia measured on the first presentation of the 2 objects days 3 and 6: On day 3, after the neophobia trial, we assessed problem-solving ability using the lid-drawer task see Supplementary Movie 1.
The birds had the opportunity to gain access to food by opening the lid or by pulling the drawer. Birds were given a maximum of 15 trials each lasting 5min. The problem-solving score was defined as the latency to succeed, which was started when the individual touched the apparatus for the first time, thus removing initial boldness or neophobia effects from the problem-solving score.
The other problem-solving task, the tunnel task, was given on day 4 of captivity. It consisted of a transparent rectangular box height: A transparent cylindrical tube containing seeds and topped with a loose fitting white lid was inserted at the closed end of the tunnel and a wooden stick was attached to it so that the birds had to pull on the stick to get the tube out of the tunnel. Once the tube was out, the bird had to remove its lid to gain access to seeds. Birds were given a maximum of 15 trials each lasting 5min, and problem-solving latency was measured in the same way it was for the lid-drawer task.
On day 5 of captivity, a color discrimination task was made to first assess acquisition learning ability. The other color thus became the rewarded one in order to control for initial color bias. The Petri dish inside the unrewarded color contained seeds glued to the bottom of the dish, so that no difference could be seen from a distance but the seeds were impossible to remove for the birds. This task was designed to measure discrimination learning without a problem-solving or motor skill component because the bird only had to choose a color without performing a novel motor task.
Novelty was also reduced because the birds were already habituated to feed from similar but not color associated Petri dishes. On each trial, the 2 platforms were introduced simultaneously inside the cage. The bird was given up to 5min to choose a dish. If the bird chose the rewarded color, it was allowed to feed for 15s. If the bird chose the unrewarded color, the 2 platforms were immediately removed by the experimenter.
Because the seeds were glued on the unrewarded side, the peck yielded no reward on this side. The location of the rewarded platform was switched at each trial to control for spatial preference. The success criterion was reached once the birds chose successively the correct rewarded color for 7 consecutive trials Boogert et al. On the day after this criterion was reached, we assessed reversal learning. We switched the rewarded color and tested the birds in the same way we did in the acquisition phase.
On the first reversal learning trial, all birds initially chose the previously rewarded color which was incorrect at this stage , indicating that they effectively learned the color stimuli, and not a potential perceptible difference in the Petri dishes. See Supplementary Figure S2 for pictures of all tasks. On completion of all tasks including boldness and neophobia assessment , birds were allowed to feed for 2min. A new task was started only when every bird had completed the previous one either success or maximum number of trials reached.
This allowed for a relatively constant food intake while keeping the birds hungry enough to be motivated. Immunocompetence was assessed using a phytohemagglutinin PHA injection, a measure of the cellular immune response. Measurement of PHA-induced swelling in birds is a well-established immunoecological technique that has the advantage of assessing general innate immunity and to a lesser extent adaptive immunity , and it is easily performed in the field Martin et al.
We measured swelling of the tissue with a micrometer caliper Mitutoyo, Mississauga, Ontario, Canada by subtracting the wing thickness before injection from thickness of the same region Loxigilla barbadensis is monochromatic, so molecular sexing of individuals is required.
The only datasets that did not follow a Gaussian distribution were the results of the 2 problem-solving tasks. Therefore, we computed the P value only for mean differences of the latter variables using a nonparametric t -test Mann—Whitney for the data presented in Figure 1b note however that the computed problem-solving PC1 followed a Gaussian distribution. To test for the effect of urbanization on all other variables along with all potential confounding variables, we performed linear models and then conducted stepwise variable selection until only significant effects remained.
For all models, tarsus length which was found to differ between rural and urban environments , sex, body weight, and body condition along with urbanization were used as explanatory variables. For neophobia, we added boldness as a potential confounding variable.
For problem-solving and discrimination learning models, we also added neophobia along with boldness as potential confounding variables. Correlations between each variable and percent urbanization as a continuous rather than a binary variable were also tested. Behavior and immunity in urban versus rural environments. Additionally, we tested whether associations between behavioral and immunity variables varied between urban and rural populations. To that aim, we built models with proxies of cognition, problem solving, or immunocompetence as response variables, and urbanization and proxies of behavior or immunocompetence along with their interactions as fixed effects.
Finally, we also tested all models using a linear mixed model LMM approach with the capture site as a random variable; the results of the latter models are presented in Supplementary Tables S1—S6. Repeatability was calculated using the rpt. For boldness, we used the latencies measured on 4 consecutive days and added the day of measurement habituation parameter in the model, as latencies usually decrease as the birds habituate to this test and to human presence in general.
For neophobia, we used the 2 measures of neophobia days 3 and 6 and added measurement day in the model. The individual ID was used as the random variable. None of the morphological traits, including body condition, differed between rural and urban birds, except tarsus length rural birds: To be conservative, we nevertheless included tarsus length as an explanatory covariable in all subsequent linear models. Final linear models after variable selection from models that included all potential confounding variables.
Following stepwise selection of variables, only urbanization remained in all models, except when stated a. Thus, t ratios and P values for only urbanization effects are compiled in this table.
The City Bird and the Country Bird
Boldness and neophobia measurements were both repeatable. The computed repeatability for boldness was 0. The repeatability for neophobia was 0. Boldness was higher in birds living in urban environments than in birds living in rural environments: Urban birds were faster at eating after human disturbance compared with rural birds Figure 1a , left panel. However, after Bonferroni corrections, boldness was no longer significantly explained by sex and only urbanization remained as a predictor of boldness see Table 2. The work was conducted at the McGill Bellairs facility in Barbados using bullfinches captured from various parts of the Caribbean island.
Why are some wild animals more tolerant to human interaction than others? Is there an evolutionary trade-off between quality signaling and social recognition? Jean-Nicolas Audet et al. The town bird and the country bird: When most wild animals first encounter humans, they respond as they would to any predator—by running, swimming or flying away. Researchers have discovered that swans' wariness is partly determined by their genes. The research, which is published in the open access journal BMC Evolutionary Biology, suggests that swans which are genetically predisposed Urban breeding birds appeared to cope better with the UK's cold, wet spring of than those living in woodland.
Faced with the same threat, city and country birds do not react in the same way despite being from the same species. According to a new study, urban birds have changed their anti-predator behaviour in new environments. Mountain chickadees Poecile gambeli , a North American bird in the tit family, store away food for later occasions. To test these predictions, we assessed problem solving, color discrimination learning, boldness, neophobia, and immunocompetence in the bullfinch Loxigilla barbadensis, a highly opportunistic and innovative endemic bird in Barbados, wild-caught from a range of differently urbanized sites.
Birds from urbanized areas were better at problem solving than their rural counterparts, but did not differ in color discrimination learning.
They were also bolder but, surprisingly, more neophobic than rural birds. Urban birds also had an enhanced immunocompetence, measured with the phytohemagglutinin antigen. Our study sheds light on the trade-offs acting on animals exposed to changing environments, particularly in the context of urbanization. Behavioural responses of wildlife to urban environments. The role of neophobia in determining the degree of foraging specialization in some migrant warblers.
Problem-solving and learning in Carib grackles: Big brains, enhanced cognition, and response of birds to novel environments. A field test of behavioural flexibility in Zenaida doves Zenaida aurita.