Fighting ability, personality and melanin signalling in free-living Eurasian tree sparrows (Passer montanus)

Abstract

Background Individuals’ access to resources is often decided during dyadic contests the outcome of which is determined by the fighting (or competitive) ability of the participants. Individuals’ fighting ability (termed also as resource-holding power or potential, RHP) is usually associated with individual features (e.g., sex, age, body size) and is also frequently signalled through various ornaments like the black throat patch (bib) in many birds. Individual personality is a behavioural attribute often linked to fighting ability as well. Based on earlier studies, however, the relationship between personality and fighting ability is far from being straightforward. While accounting for sex and body size, we studied whether exploratory behaviour, an aspect of personality, predicts fighting ability when competing for food during winter in free-living Eurasian tree sparrows (Passer montanus). We also investigated whether the bib can serve as a potential indicator of individual competitiveness in this species. Methods We captured adult tree sparrows, marked them with a unique combination of colour rings, and collected data about the individuals’ sex, body size, bib size and exploratory behaviour. Birds were then released and the agonistic behaviour of the marked individuals was recorded while foraging in groups on bird feeding platforms. Results The probability of winning a fight, a proxy for fighting ability of individuals, was not related to exploratory behaviour, in either of the sexes. However, bib size was positively related to probability of winning in females, but not in males. Body size was not associated with probability of winning neither in males, nor in females. Conclusions Our results suggest that, at least in tree sparrows, the outcome of dyadic encounters over food during the non-breeding period are not determined by the exploratory personality of individuals. However, our findings provide further support for a status signalling role of the black bib in tree sparrows, and hint for the first time that bib size might function as a status signal in females as well. Finally, our results do not confirm that body size could serve as an indicator of fighting ability (i.e., RHP) in this species.

Space use of wintering Eurasian Tree Sparrows (Passer montanus) in a semi-urban area: a radiotelemetry-based case study

“…We captured six Tree Sparrows at two different feeders (details in Table 1), with mist nets (Ecotone, Poland), following the protocol described in details by Fülöp et al (2019Fülöp et al ( , 2022. Briefly, at capture, we marked the individuals with a uniquely numbered aluminium ring, issued by the Hungarian Bird Ringing Centre, and with a unique combination of three plastic colour rings to assure individual identification from a distance (see also Fülöp et al 2019Fülöp et al , 2022. We measured body mass (± 0.1 g with a Pesola spring balance), tarsus length (± 0.01 mm with a digital calliper), and wing length (± 0.5 mm with a ruler) of individuals, and we photographed their black bib patch (see e.g.…”

“…We also took a blood sample (~50-150 μL) from the brachial vein of each individual to perform molecular sexing (see details in Fülöp et al 2021). The captured birds were subjected to a personality test as well for parallel studies (Fülöp et al 2019(Fülöp et al , 2021(Fülöp et al , 2022. Finally, we fitted a radio tag (model PIP3, Biotrack Ltd., UK; weight 0.43 g) on the back of each individual using flexible super glue (Loctite 4860).…”

Recognizing interspecific dominance signals? Blue tits adjust nest defence based on great tit's black bib size

“…Many colours, morphological structures, and ritualized behaviour in animals are social indicators that reveal information about dominance and the ability of the bearer to obtain resources such as food, nesting sites, mates, and territories in agonistic contexts (i.e. resource‐holding potential [RHP]) (Fülöp et al., 2022; Hill & McGraw, 2006; Quesada et al., 2013; Santos et al., 2011; Setchell & Jean Wickings, 2005; Vedder et al., 2010). The adaptive advantage of these signals helps avoid unnecessary conflicts and lessens the risk of injury that could harm the individuals involved in agonistic conflicts (Hinde, 1966; Maynard Smith & Harper, 2003; Searcy & Nowicki, 2005; Senar, 2006; Zahavi, 1980).…”