Dominant male song performance reflects current immune state in a cooperatively breeding songbird

Abstract

Conspicuous displays are thought to have evolved as signals of individual “quality”, though precisely what they encode remains a focus of debate. While high quality signals may be produced by high quality individuals due to “good genes” or favourable early‐life conditions, whether current immune state also impacts signalling performance remains poorly understood, particularly in social species. Here, we experimentally demonstrate that male song performance is impaired by immune system activation in the cooperatively breeding white‐browed sparrow weaver (Plocepasser mahali). We experimentally activated the immune system of free‐living dominant males via subcutaneous injection of phytohemagglutinin (PHA) and contrasted its effects with those of a control (phosphate buffered saline) injection. PHA‐challenged males showed significant reductions in both the duration and the rate of their song performance, relative to controls, and this could not be readily attributed to effects of the challenge on body mass, as no such effects were detected. Furthermore, male song performance prior to immune‐challenge predicted the scale of the inflammatory response to the challenge. Our findings suggest that song performance characteristics are impacted by current immune state. This link between current state and signal performance might therefore contribute to enforcing the honesty of signal performance characteristics. Impacts of current state on signaling may be of particular importance in social species, where subordinates may benefit from an ability to identify and subsequently challenge same‐sex dominants in a weakened state.

The songs of male pied flycatchers: exploring the legacy of the fathers

“…Females may select a male based on the information encoded in his songs, as different song traits may convey honest information about male characteristics or conditions (Nowicki, Peters & Podos, 1998; Gil & Gahr, 2002), such as their phenotypic (Richner, 2016) or genetic quality (Ferrer et al, 2015), and age (Espmark & Lampe, 1993; Kipper & Kiefer, 2010; but see Motes-Rodrigo, Labra & Lampe, 2017). In addition, song traits may reveal males’ physiological states (e.g., developmental stress (Nowicki et al, 2000; Spencer et al, 2005b), immune condition (York et al, 2016), body condition (Lampe & Espmark, 1994; Mountjoy & Lemon, 1996), or parasite levels (Spencer et al, 2005a)), as well as some of their behavioral characteristics (e.g., quality of the territories (Lampe & Espmark, 2003; Ritschard & Brumm, 2012), ability to provide paternal care (Buchanan & Catchpole, 2000; but see Rinden et al, 2000), or breeding experience (Lampe & Espmark, 1994; Motes-Rodrigo, Labra & Lampe, 2017)). Thus, it is not surprising that the fitness of males may be associated with song traits, such as song duration (Searcy et al, 2010), versatility (Järvi, 1983; Lampe & Espmark, 2003), or complexity (Soma & Garamszegi, 2011, but see Byers & Kroodsma, 2009; Potvin et al, 2015).…”

Experimental inhibition of a key cellular antioxidant affects vocal communication

“…) and in white‐browed sparrow weavers (York et al . ), or rattle duration in barn swallows Hirundo rustica (Dreiss et al . ).…”

“…There are clearly constraints that limit song expression. For example, it has been shown that immunization can reduce song rate in collared flycatchers Ficedula albicollis ) and in white-browed sparrow weavers (York et al 2016), or rattle duration in barn swallows Hirundo rustica (Dreiss et al 2008). Recent studies in male European starlings found that inflammatory processes significantly decreased song rate and that the antibody production caused a moderate reduction of one particular mode of singing (undirected song rate, i.e.…”

Sexually selected sentinels? Evidence of a role for intrasexual competition in sentinel behavior

“…White-browed sparrow weaver males sing a distinct song type during the breeding season, known as the solo song (see Voigt et al 2006 for a spectogram of solo song). It is sung principally by dominant males, typically at dawn but also during the day, particularly during peak reproductive periods following high rainfall ( Wingfield and Lewis 1993 ; Voigt et al 2006 ; York 2012 ; York et al 2016 ). Extra-group males are known to intrude on occupied territories, where they have been observed producing solo song, eliciting vocal and physical responses (chases) from the resident dominant male.…”