Abstract:Non‐consumptive predator effects have been shown to influence a wide range of behavioural, life history and morphological traits. Extra‐pair reproduction is widespread among socially monogamous birds and may incur predation costs. Consequently, altered rates of extra‐pair reproduction are expected in circumstances characterized by increased adult perceived predation risk.
In addition, extra‐pair reproduction is expected to be most affected for birds with phenotypes that generally increase predation risk (such … Show more
“…Our playback design may have also altered individuals’ perception of temporal variance in risk, another factor influencing anti-predator behavior 13 , although competing theories debate whether mean rather than variance is important for prey to interpret predator cues 14 . Birds decreased risky communication behaviors (detailed above) in the high-PPL treatment but actual predator numbers were not affected (based on weekly counts) 15 , verifying that our manipulations influenced perceived—not actual—predation levels. In this vein, our aim with this study is to determine how behavioral types differ in their adjustment of reproductive investment in response to perceived levels.Fig.…”
Section: Introductionsupporting
confidence: 51%
“…Here, treatment was fitted as a two-level categorical variable (low vs. high PPL). Random intercepts were further fitted for the unique combination of plot and year (PlotYear; n = 12 plots × 2 years = 24 levels) as treatment varied at this level, thereby avoiding pseudo-replicated values of P for effects of treatment 10,15,18 . Random intercepts were also fitted for individual identity, where female (rather than male) identity was assigned in analyses of lay date and clutch size because our previous work showed that female rather than male identity determines such life-history traits 18 .…”
The adaptive evolution of timing of breeding (a component of phenology) in response to environmental change requires individual variation in phenotypic plasticity for selection to act upon. A major question is what processes generate this variation. Here we apply multi-year manipulations of perceived predation levels (PPL) in an avian predator-prey system, identifying phenotypic plasticity in phenology as a key component of alternative behavioral strategies with equal fitness payoffs. We show that under low-PPL, faster (versus slower) exploring birds breed late (versus early); the pattern is reversed under high-PPL, with breeding synchrony decreasing in conjunction. Timing of breeding affects reproductive success, yet behavioral types have equal fitness. The existence of alternative behavioral strategies thus explains variation in phenology and plasticity in reproductive behavior, which has implications for evolution in response to anthropogenic change.
“…Our playback design may have also altered individuals’ perception of temporal variance in risk, another factor influencing anti-predator behavior 13 , although competing theories debate whether mean rather than variance is important for prey to interpret predator cues 14 . Birds decreased risky communication behaviors (detailed above) in the high-PPL treatment but actual predator numbers were not affected (based on weekly counts) 15 , verifying that our manipulations influenced perceived—not actual—predation levels. In this vein, our aim with this study is to determine how behavioral types differ in their adjustment of reproductive investment in response to perceived levels.Fig.…”
Section: Introductionsupporting
confidence: 51%
“…Here, treatment was fitted as a two-level categorical variable (low vs. high PPL). Random intercepts were further fitted for the unique combination of plot and year (PlotYear; n = 12 plots × 2 years = 24 levels) as treatment varied at this level, thereby avoiding pseudo-replicated values of P for effects of treatment 10,15,18 . Random intercepts were also fitted for individual identity, where female (rather than male) identity was assigned in analyses of lay date and clutch size because our previous work showed that female rather than male identity determines such life-history traits 18 .…”
The adaptive evolution of timing of breeding (a component of phenology) in response to environmental change requires individual variation in phenotypic plasticity for selection to act upon. A major question is what processes generate this variation. Here we apply multi-year manipulations of perceived predation levels (PPL) in an avian predator-prey system, identifying phenotypic plasticity in phenology as a key component of alternative behavioral strategies with equal fitness payoffs. We show that under low-PPL, faster (versus slower) exploring birds breed late (versus early); the pattern is reversed under high-PPL, with breeding synchrony decreasing in conjunction. Timing of breeding affects reproductive success, yet behavioral types have equal fitness. The existence of alternative behavioral strategies thus explains variation in phenology and plasticity in reproductive behavior, which has implications for evolution in response to anthropogenic change.
“…Recent work has shown that the perceived risk of predation can have substantial effects on prey species by suppressing their reproductive success, and the non-consumptive effects of predators thus represent a significant selection pressure (Basso & Richner, 2015;Ghalambor et al, 2013;Hua et al, 2014;LaManna & Martin, 2016;Sheriff et al, 2009;Zanette et al, 2011, but see Santema, Valcu, Clinchy, Zanette, & Kempenaers, 2019b. The results of our study suggest that non-consumptive effects of predators may also affect the distribution of reproduction and thus have consequences for sexual selection, a possibility that has received less attention (Abbey-lee et al, 2018;Yuta & Koizumi, 2016).…”
Section: Discussionmentioning
confidence: 78%
“…The results of our study differ from those of two previous studies that experimentally examined effects of perceived predation risk on extra‐pair paternity. Abbey‐Lee et al () exposed great tits Parus major to calls of their main predator, the sparrowhawk Accipiter nisus , throughout the breeding period, while Santema et al () exposed blue tits Cyanistes caeruleus to calls of multiple predator species throughout the breeding period. Neither of these studies found an effect on extra‐pair paternity.…”
Section: Discussionmentioning
confidence: 99%
“…A large body of research has tried to explain this variation (Petrie & Kempenaers, 1998), with mixed success (Forstmeier, Nakagawa, Griffith, & Kempenaers, 2014). A hypothesis that remains largely untested is that levels of extra-pair paternity are affected by the perceived risk of predation (Abbey-Lee et al, 2018). This is plausible, because soliciting (extra-pair) copulations and copulating itself may attract predators (Hughes, Kelley, & Banks, 2012;Magnhagen, 1991) and individuals may thus reduce the frequency of these behaviours in response to an increase in perceived predation risk (Gibson & Langen, 1996;Westneat, Sherman, & Morton, 1990).…”
The perceived risk of predation can affect breeding behaviour and reduce reproductive success in prey species. Individuals exposed to predators may also adopt different mating tactics with potential consequences for the distribution of paternity in socially monogamous species that engage in extra‐pair copulations.
We experimentally increased perceived predation risk during the fertile period in blue tits Cyanistes caeruleus. Every morning between nest completion and the onset of egg laying, we presented a model of either a predator or a non‐predator (control) near active nestboxes.
Broods from pairs exposed to predators had higher levels of extra‐pair paternity than control broods. This mainly resulted from a higher proportion of extra‐pair offspring in broods with at least one extra‐pair young.
Females exposed to predators first emerged from the nestbox later in the morning, stayed away from the nestbox for longer and were less likely to be visited at the nest by their social mate, but we detected no behavioural differences once the model was removed.
Our results suggest that the higher rates of extra‐pair paternity resulted from the disruption of morning routines, which may have inhibited within‐pair copulations or increased opportunities for females to engage in extra‐pair copulations. We conclude that the perceived risk of predation can have substantial effects on levels of extra‐pair paternity.
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