Scientists have shown that birds with higher stress levels adopt bolder behaviour than their normally more relaxed peers in stressful situations. A University of Exeter research team studied zebra finches, which had been selectively bred to produce three distinct types – ‘laid-back’, ‘normal’ and ‘stressed’ – based on their levels of stress hormone.
The group was surprised to find that the ‘stressed’ birds were bolder and took more risks in a new environment than the group that was usually more laid-back. Their findings are published today (26 October) in the journal Hormones and Behaviour.
Like other animals including humans, birds respond to stress, created by the appearance of a predator or a change in their environment for example, by producing a hormone. In birds, this hormone is called ‘corticosterone’ and some individuals have higher levels of the hormone than others. The zebra finches in this experiment were bred to have three different corticosterone levels, with the ‘laid-back’ birds having lower levels than the ‘stressed’ birds.
The researchers put the birds into a new environment, which housed several unfamiliar objects, including new feeders. The ‘stressed’ birds were the first to visit the new feeders, which they also returned to more quickly than the other birds after being startled. Overall, they approached more objects than their normally more relaxed peers, showing greater risk-taking behaviour and arguably handling the situation better.
Dr Thais Martins of the University of Exeter said: “It initially seems counter-intuitive that birds with higher levels of the stress hormone showed bolder behaviour, normally associated with confidence. However, corticosterone is released to help tackle stress by encouraging the animal to adopt key survival behaviours like seeking food. So on reflection, perhaps it is not surprising that these birds are more likely to explore the environment and look for food.”
Previous research has indicated that animals show consistent individual differences in their behaviour when faced with certain challenges. Traditionally in this field of research, birds have been separated into two groups: ‘bold’ and ‘shy’, or ‘active’ and ‘passive’. These definitions are based on observations of their behavioural strategies, and the birds are then studied for physiological differences. This research took the opposite approach and separated the birds into groups by physiology, based on corticosterone production levels, and then looked for behavioural differences.
Source: University of Exeter
Related stories:
Ski tourism stresses European capercaillie
Swiss, German and Austrian scientists said ski tourism might be harming capercaillie -- an old world grouse -- by affecting their ability to breed.
Ski tourism stressing capercaillie
Ski tourism is raising stress levels among capercaillie, which could harm the birds’ fitness and ability to breed successfully, ecologists have found. Writing in the
British Ecological Society’s Journal of Applied Ecology, researchers warn that forests should be kept free from tourism infrastructure if they are inhabited by capercaillie - a species whose numbers are declining markedly across central Europe.
Herons persist in Chicago wetlands despite exposure to banned chemicals
Herons nesting in the wetlands of southeast Chicago are still being exposed to chemicals banned in the U.S. in the 1970s, a research team reports. The chemicals do not appear to be affecting the birds’ reproductive success, however. The findings appear in the current issue of the
Journal of Great Lakes Research.
Understanding, combating foodborne pathogens E. coli 0157 and salmonella
Understanding the ecology of two dangerous foodborne pathogens and devising ways to combat them is a big job. That's why Kansas State University has a team of seven researchers and six collaborators taking on E. coli 0157 and salmonella.
Scientists shake Darwin's foundation -- chickens inherited parents' stress symptoms
Evolutionary theory ever since Darwin is based on the assumption that acquired traits, such as learnt modifications of behaviour, cannot be inherited by the offspring. Now, a Swedish-Norwegian research group, led by professor Per Jensen at Linköping university in Sweden, shows that chickens can actually inherit behavioural modifications induced by stress in their parents.
Extreme Weather Leaves Flamingos Hungry
Lesser flamingos (Phoeniconaias minor) at Lake Bogoria, Kenya, are suffering from malnutrition, report Earthwatch-supported scientists working there. The scientists are investigating the causes of recent large-scale mortality events, resulting in the death of thousands of lesser flamingos in Kenya last year and at least half a million birds during the 1990s.
Too mellow for our predatory world
Marine iguanas on the Galapagos Islands live without predators - at least this was the case up until 150 years ago. Since then they have been confronted with cats and dogs on some islands of the Archipelago. For scientists, they are therefore a suitable model of study in order to discover if such generally tame animals are capable of adapting their behaviour and endocrine stress response to novel predation threats.
'Stress and the city': Urban birds keep cool
Animals colonizing cities are exposed to many novel and potentially stressful situations. Chronic stress, however, can cause deleterious effects. Hence, wild animals would suffer from city life unless they adjusted their stress response to the conditions in a city.