| Summary: | <p>By using European badgers (Meles meles) as a model species, my thesis examines how wild mammalian populations utilise olfactory communication via specialised glandular secretions and metabolic by-products when advertising fitness-related information to conspecifics. This research utilised bomb calorimetry to quantify energetic content within subcaudal gland secretion (a uniquely evolved scent gland), enzyme immunoassays to measure sex-steroid levels within urine, and scent-provisioning experiments which assessed behavioural responses to particular scent marks.</p>
<p>Compared to other communication modalities, olfactory communication allows conspecifics to exchange individual- and group-related information without both parties (signaller and receiver) being present simultaneously. Section I addresses the factors that olfactory signals/cues must possess in order to be effective and common methodologies used within semiochemical research. Section II addresses olfactory advertisement with specialised glandular secretions with a focus on the specially evolved subcaudal gland and the secretion production costs incurred by individuals. By using bomb calorimetry and scent-provisioning experiments, I found that i) the energetic content of subcaudal secretion varies significantly based on individual fitness and season, and ii) conspecific responses vary their behavioural responses based on the perceived energetic costs along with donor-related traits (i.e., age and sex).</p>
<p>Metabolic by-products (e.g., urine) incur minimal production costs compared to specialised glandular secretions. Chemical profiles within urine vary depending on individual parameters, and Section III addresses if/how information encoded within urine influences conspecific responses. My findings indicated that, throughout the year, adult females responded more than adult males to urine marks while urine marks from non-resident badgers – particularly badgers from neighbouring setts – elicited more responses. Additionally, adults and cubs adjusted their behaviour accordingly when presented with urine from different species, suggesting that badgers utilise olfactory cues in risk determination.</p>
<p>Section IV concludes my thesis by comparing the utilisation of subcaudal gland secretions and urine within olfactory fitness advertisement. Overall, subcaudal gland secretions appear to function as a primary source for individual fitness information while urine serves a subsidiary role in fitness advertisement. Avenues for future research – particularly longitudinal studies involving the correlation of behavioural responses to reproductive output – are discussed.</p>
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