Utilising sound as a means of reducing stress in captive birds
Housing conditions are crucial to animal wellbeing. For example, providing hiding places and manipulatable objects is associated with significant reductions in physiological stress responses and abnormal behaviour. However, little attention has been paid to sound as a both a potential stressor and a means of enrichment. Captive animals are often exposed to poor acoustic environments, which contain elevated levels of anthropogenic noise and reduced levels of sounds that occur in their natural environments. In wild animals, anthropogenic noise has been shown to be a stressor that disrupts behaviour: it alters foraging efficiency, reproductive activities, social behaviours, and communication signals – even in species that do not rely on acoustic communication. Noise also has widespread physiological impacts on the neuroendocrine, reproductive, and immune systems.
It is vital that we understand how the sounds experienced in laboratories affect behavioural and physiological welfare indicators such as social and cognitive functioning, stress responsiveness, and immunocompetence and disease susceptibility. Understanding how ‘soundscapes’ can alter phenotypic traits also provides an opportunity to potentially enrich laboratory environments via simple low-cost techniques, and enhance welfare.
Stress in Lobsters
The European lobster (Homarus gammarus) was worth almost £19m to Scotland’s fishing industry in 2018. Lobster stocks in Scotland are currently data deficient, however, undersized animals are likely to be caught and returned to the sea many times before they reach the minimum legal size to be landed. Highly spatially and temporally resolved fishing activity data suggests that localised fishing pressure may be very intense, resulting in repeated exposure to stressors including entrapment and handling, emersion hypoxia, interactions with other lobsters, and physical damage. This is concerning, as elevated stress levels have been shown to impact immune function, reproductive success, cognitive function, and result in mortality in a range of taxa. Here, I am collaborating with researchers at the Scottish Oceans Institute to investigate the impact of repeated capture/discard of undersized lobsters on their physiology.
Maternal hormones and offspring sex ratio
Sex allocation theories claim animals should adjust the sex of their offspring in response to environmental conditions, to maximise their lifetime reproductive success. Avian females can manipulate offspring sex, by influencing which sex chromosome is retained in the ovulated oocyte and which is discarded. As yet, the mechanism for sex allocation is unclear, despite wide theoretical and empirical support. This research investigates the potentially mechanistic role of circulating steroid hormones in birds (e.g. previous work on maternal testosterone in laying hens, and maternal corticosterone in zebra finches). Ultimately, I hope to use this as a tool to manipulate offspring sex ratios, which would be an important development for conservation and in the poultry industry.