Seasonal variation in diet quality: antioxidants, invertebrates and blue tits Cyanistes caeruleus

Abstract

Breeding success is often dictated by the degree to which parents can synchronize the maximum food requirements of offspring to the peak in abundance of invertebrate prey. Less studied is how the nutritional quality of individual diet items impacts on breeding. In the present study, we assessed the abundance and antioxidant concentrations of arboreal arthropods from oak woodland and provisioning behaviour of the blue tit Cyanistes caeruleus. Dietary antioxidants are important during development because they defend against oxidative stress. Operophtera caterpillars, Erannis caterpillars, and spiders contained significantly different levels of individual carotenoids and a-tocopherol. Concentrations of lutein and b-carotene in Operophtera caterpillars did not vary seasonally, although concentrations of zeaxanthin declined and a-tocopherol increased with date. Blue tit broods hatched later in the season received significantly fewer caterpillars and more spiders per chick compared to earlier broods. Reflecting changes in prey composition, blue tit nestling plasma showed decreases in zeaxanthin and increases in a-tocopherol with date. Thus, processes that shift the timing of breeding in birds and/or prey composition are likely to alter antioxidant intake and thus potentially influence the oxidative stress status of animals. The data obtained in the present study suggest a mechanism by which environmental change as a result of human activities could influence the health and fitness of individuals in natural populations.

Prey choice, provisioning behaviour, and effects of early nutrition on nestling phenotype of titmice

“…Along these lines, we have shown previously that to feed young with one or the other type of caterpillar is not a trivial matter from the point of view of the offspring . In this sense, recent studies (Arnold et al, 2010;Eeva et al, 2010) have shown that lepidopteran larvae can differ greatly in their concentration of carotenoids (antioxidants such as lutein, zeaxanthin, β-carotene). On the basis of their appearance and the birds' preference, it is likely that noctuids (caterpillars with a greater amount of tissue) possess a higher caloric content in comparison with tortricid larvae, whose aspect is less consistent (watery guts) and nutritive.…”

The importance of a main dish: nestling diet and foraging behaviour in Mediterranean blue tits in relation to prey phenology

“…Lepidoptera larvae differ greatly in their size, shape, mobility (Gómez de Aizpurúa 2003) and carotenoid level (Isaksson and Andersson 2007;Arnold et al 2010) and, consequently, the fact that birds feed their young with one or another species is not trivial. We have shown that diet features seem to have an effect on nestling condition, which is a critical determinant of post-fledging survival (Greño et al 2008) and recruitment rate (Both et al 1999).…”

Darker eggshell spotting indicates lower yolk antioxidant level and poorer female quality in the Eurasian Great Tit (Parus major)

“…Females that lay smaller clutches may have lower intrinsic quality or they may breed in poorer-quality territories and thus they may be exposed to lower food availability, insufficient for laying more eggs in a clutch (Minot 1981, Perrins andMcCleery 1989). Female Great Tits consume high numbers of caterpillars during the breeding period (Török 1986), which are rich in dietary antioxidants (Arnold et al 2010, Eeva et al 2010. We may thus assume that females with a lower availability of antioxidant-rich food laid smaller clutches and possibly also possessed a less efficient antioxidant capacity during the laying period.…”