Repeatability of Host Female and Male Aggression Towards a Brood Parasite

Abstract

Current research on behavioural consistency showed that various types of animal behaviour are highly repeatable in the context of mate choice, exploration and parental care, including nest protection. However, the repeatability of aggressive nest defence has not yet been studied in hosts of brood parasites, although host aggression against adult parasites represents a crucial line of antiparasitic defences. Here, we investigated the between‐season repeatability of the great reed warbler (Acrocephalus arundinaceus) aggression towards a stuffed dummy of the brood parasitic common cuckoo (Cuculus canorus). We found that under the relatively stable risk of brood parasitism across breeding seasons, female responses to the cuckoo were highly repeatable, whereas male responses were variable. We suggest that the potential explanation for the observed patterns of female and male behaviours may lie in female's prominent roles in offspring care and nest protection, and in her lower renesting potential in comparison with that of males. However, further studies on the relationship between host aggression and other types of behaviours (host personality) and their fitness consequences under the fluctuating parasitism pressures are required to clarify the adaptive significance of aggressive behaviour observed in hosts of brood parasites.

Pairing status moderates both the production of and responses to anti‐parasitic referential alarm calls in male yellow warblers

“…Interestingly, chip production for yellow warblers in general also varied over the breeding season for some treatments, with significantly more chip calls being produced toward blue jay playbacks later in the season, and less chip calls toward cowbirds. Similar patterns have been observed in other alarm‐calling species from nest predator (see Montgomerie & Weatherhead, 1988, for review) and brood parasite (Brooke et al., 1998; Trnka et al., 2013) presentation studies. These responses may be due to lower benefits of renesting later in season and the typically reduced parasitism pressure over time (Montgomerie & Weatherhead, 1988; Trnka et al., 2013).…”

Plasticity in extended phenotype increases offspring defence despite individual variation in web structure and behaviour

“…The most common of these threats comes from predators, to which parents often defend against using a variety of aggressive behaviours, from mobbing and alarm calling in avian species ( Hollander, Van Overveld, Tokka, & Matthysen, 2008 ; Redondo & Carranza, 1989 ; Wiklund, 1990 ), to biting and lunging in fish ( Itzkowitz, 1985 ; Ridgway, 1988 ), to striking and grabbing with chelae in crayfish ( Figler, Blank, & Peeke, 2001 ; Martin & Moore, 2010 ). Similar behaviours are used to counter other biotic threats such infanticidal females ( Wolff & Peterson, 1998 ) and brood parasites ( Trnka, Požgayová, Samaš, & Honza, 2013 ). Defending against these threats yields obvious fitness benefits in the form of offspring survival, yet comes at a potential cost of injury or death to parents.…”

“…Such individual differences may also occur in the context of nest defence, whereby some individuals invest more in protecting their offspring than others ( Burtka & Grindstaff, 2013 ). Recently, a number of studies on avian species have demonstrated such individual differences in behavioural nest defences, measured by repeatability, whereby individual females are consistent across breeding seasons in how intensely they defend their nests ( Burtka & Grindstaff, 2013 ; Hollander et al, 2008 ; Trnka et al, 2013 ). This raises the question of how those individuals who consistently invest less in behavioural defence compensate for the potential fitness losses.…”

Evolutionary significance of antiparasite, antipredator and learning phenotypes of avian nest defence

“…We tested for antipredator behaviours that instead resulted as enemy-specific responses in yellow 32 and reed 33 warblers (Supplementary Table 1 ). Model presentations conducted within the above-cited investigations are part of a long-used field-experimental technique, largely shown to be a reliable test to discriminate abilities and information transfer (Supplementary Methods) 12 , 16 , 32 , 50 .…”