Trade‐offs between reproduction and self‐maintenance (immune function and body mass) in a small seabird, the little auk

Abstract

Breeding season is the most energetically and physiologically demanding phase in the avian annual cycle, challenging adults' physiology and survival. However, the timing and extent that self‐maintenance of breeding adults is compromised during the breeding season is poorly understood. We investigated the trade‐off between reproduction and self‐maintenance in relation to breeding phase (prelaying, incubation, chick rearing) and sex in a small Arctic seabird, the little auk Alle alle. To measure a bird's allocation of time for self‐maintenance, we examined size‐adjusted body mass and immunocompetence expressed by bacteria (Escherichia coli) killing capacity (BKC) of blood plasma, heterophils/lymphocyte ratio (H/L) and their numbers of particular leucocytes per 10 000 red blood cells (RBC). We found that size‐adjusted body mass decreased as the breeding season progressed. BKC, number of heterophils and H/L values were all was significantly higher at prelaying when compared to all other phases. Interestingly, we found that heavier individuals had higher BKC and number heterophils at the prelaying and chick rearing phases than light individuals. There were no differences by sex in any studied variables. Our results indicate that immunocompetence and body mass of breeding adults decreases over the course of breeding season. The efficiency of the immune system appears to be dependent on the bird's body reserves. Our results suggest that little auks allocation of resources into reproduction negatively affects their self‐maintenance.

Breeding phased dependent oxidative balance in a small High Arctic seabird, the little auk

“…We suggest that those differences may be attributed to breeding stage dependent changes in hormone levels, that in turn, affect various haematological parameters, including the oxidative status. Lack of sex differences in the oxidative status, along with some other studies (Wojczulanis- , 2014, Kulaszewicz et al 2017, further undermines hypothesis about the little auk female ceasing the chick provisioning earlier than male due to her worse body condition. Nevertheless, since our study is correlational with a cross-sectional design, to fully comprehend seasonal changes in OS and hormones as well as causality of the observed patterns, further, preferably experimental studies are needed, possibly also including earlier breeding stages.…”

Effects of back‐mounted biologgers on condition, diving and flight performance in a breeding seabird

“…Both common and Brünnich's guillemots reduce body mass following incubation at the onset of chick rearing (Birkhead and Nettleship 1987, Harris and Wanless 1988, Croll et al 1991, Gaston and Perin 1993, Elliott et al 2008b), which is observed in other seabird species too (Niizuma et al 2001, Schultner et al 2013, Kulaszewicz et al 2016). In guillemots, this reduction in adult body mass post‐hatching can be quite rapid, resulting in ca 5–10% body mass loss over just a few days (Gaston and Perin 1993).…”

Evidence of incubation trade‐offs in Leach's Storm‐Petrel (Oceanodroma leucorhoa): ptilochronology as a measure of reproductive investment in a long‐lived seabird

“…Meanwhile, a study of Little Auks Alle alle found that the adults themselves suffered a cost of reproduction to their immune function instead of the chicks (Kulaszewicz et al . 2017), a strategy more commonly expected in short‐lived species (Tinbergen & Williams 2002). Saino et al .…”