Benefits of extra food to reproduction depend on maternal condition

Abstract

The amount of food resources available to upper‐level consumers can show marked variations in time and space, potentially resulting in food limitation. The availability of food resources during reproduction is a key factor modulating variation in reproductive success and life‐history tradeoffs, including patterns of resource allocation to reproduction versus self‐maintenance, ultimately impacting on population dynamics. Food provisioning experiments constitute a popular approach to assess the importance of food limitation for vertebrate reproduction. In this study of a mesopredatory avian species, the lesser kestrel Falco naumanni, we provided extra food to breeding individuals from egg laying to early nestling rearing. Extra food did not significantly affect adult body condition or oxidative status. However, it increased the allocation of resources to flight feathers moult and induced females to lay heavier eggs. Concomitantly, it alleviated the costs of laying heavier eggs for females in poor body condition, and reduced their chances of nest desertion (implying complete reproductive failure). Extra food provisioning improved early nestling growth (body mass and feather development). Moreover, extra food significantly reduced the negative effects of ectoparasites on nestling body mass, while fostering forearm (a flight apparatus trait) growth among highly parasitized nestlings. Our results indicate that lesser kestrels invested the extra food mainly to improve current reproduction, suggesting that population growth in this species can be limited by food availability during the breeding season. In addition, extra food provisioning reduced the costs of the moult–breeding overlap and affected early growth tradeoffs by mitigating detrimental ectoparasite effects on growth and enhancing development of the flight apparatus with high levels of parasitism. Importantly, our findings suggest that maternal condition is a major trait modulating the benefits of extra food to reproduction, whereby such benefits mostly accrue to low‐quality females with poor body condition.

Extra food provisioning reduces extra‐pair paternity in the lesser kestrel Falco naumanni

“…In birds, conditions favouring intraspecific brood parasitism may include limitation of female ability to breed in adverse environmental conditions, clutch loss due to predation during egg laying, the occurrence of alternative reproductive tactics, or simply the occurrence of constraints in obtaining a breeding territory or mate (see Lyon and Eadie 2008 for a detailed review). In our lesser kestrel population, clutch loss due to predation is extremely rare, and in the study year the ecological conditions were generally favourable (Podofillini et al 2019). The occurrence of intraspecific brood parasitism may thus be explained by the presence at the colony of prospecting yearling females, which mostly do not breed despite being sexually mature (Hiraldo et al 1996).…”

“…Extra food did not significantly affect SMI or morphology (F 1,68 < 2.91, p > 0.09); these models also revealed that females had significantly shorter tarsi (F 1,68 = 5.97, p = 0.02) and larger SMI (F 1,67 = 51.35, p < 0.001) as compared to males (see Podofillini et al 2019 for further details). Twoway interactions between food supplementation and sex were not significant (F 1,66 < 1.78, p > 0.19).…”

Inter-individual differences in foraging tactics of a colonial raptor: consistency, weather effects, and fitness correlates

“…The lesser kestrel is a sexually dimorphic species, females being ca. 15% heavier than males [54]. Females lay up to 5 eggs that both parents incubate for ca.…”

“…7 and ca. 14 days after hatching of the first egg) [53,54]. Breeding individuals were captured by hand within nestboxes during the late incubation and early nestling-rearing stage.…”

Maternal food supplementation and perceived predation risk modify egg composition and eggshell traits but not offspring condition

“…Food availability during breeding can strongly affect parental investment, egg composition and, subsequently, offspring growth and condition. For example, food-supplemented birds have been found to lay larger clutches and eggs (Zanette et al, 2006a;Karell et al, 2008;Benowitz-Fredericks et al, 2013;Ruffino et al, 2014;Ruuskanen et al, 2016;Podofillini et al, 2019; but see Giordano et al, 2015a) or vary their transfer of hormones and immune factors to eggs (Gasparini et al, 2007;Benowitz-Fredericks et al, 2013;Morosinotto et al, 2016; but see Ruuskanen et al, 2016). Maternal food supplementation is also known to shorten incubation duration and lead to increased offspring mass, condition and immune defence (Pihlaja et al, 2006;Karell et al, 2008;Moreno et al, 2008;Vafidis et al, 2016;Podofillini et al, 2019; but see Verboven et al, 2003).…”