Offspring growth and mobility in response to variation in parental care: a comparison between populations

Abstract

Life history theory emphasizes the importance of trade‐offs in how time and energy are allocated to the competing demands of growth, fecundity, and survival. However, avian studies have historically emphasized the importance of resource acquisition over resource allocation to explain geographic variation in fecundity, parental care, and offspring development. We compared the brood sizes and nestling mass and feather growth trajectories between orange‐crowned warblers Oreothlypis celata breeding in Alaska versus California, and used 24‐h video recordings to study the relationship between parental care and growth rates. Per‐offspring provisioning rates were highest in the smallest broods, and food delivery was positively correlated with nestling growth over the 24‐h period only in Alaska. Females in Alaska spent more time brooding, and juveniles there showed faster feather growth and earlier mobility compared with those in California. We also found differences in the energetic and nutritional content of insect larvae that could facilitate the observed differences in nestling growth relative to food provisioning. Our results point to the potential importance of food quality and parental provisioning of warmth, in addition to food, for explaining avian growth patterns. We highlight the need to quantify multiple dimensions of parental care and of offspring growth and development, and to better understand the relationships between feather growth, nestling period length, and fledgling mobility.

Hierarchical fear: parental behaviour and corticosterone release mediate nestling growth in response to predation risk

“…Adults decreased provisioning rates in response to greater perceived predation risk which had subsequent negative impacts on nestling wing growth. Reduced provisioning rate in the presence of predators may help avoid nest detection (Martin et al 2000), but the resulting resource limitations can constrain nestling growth (Dunn et al 2010, Sofaer et al 2018). Interestingly, provisioning rate did not directly influence nestling wing growth but instead was associated with wing length through a corticosterone response.…”

Variation in offspring development is driven more by weather and maternal condition than predation risk

“…Species experiencing low predation risk tend to prolong offspring development, potentially to maximize post-fledging survival (Martin, Tobalske, Riordan, Case, & Dial, 2018) and minimize the negative long-term fitness consequences of oxidative stress associated with rapid development (Lee, Monaghan, & Metcalfe, 2013). Studies addressing among-and within-population variation have provided support for additional influential drivers of offspring development duration, including: inclement weather (Pérez et al, 2016), microclimate temperature (Dawson, Lawrie, & O'Brien, 2005;Sofaer et al, 2018) and food availability (Stodola et al, 2010;Tuero et al, 2018). Variation in influential factors across populations challenges the generality of predation risk as the predominant driver.…”

The evolution of life history theory: Bibliometric analysis of an interdisciplinary research area

“…Indeed, within these clusters, the fast-slow continuum is presented as the central defining idea that individuates life-history theory as opposed to other approaches. In fact, though, the fast-slow continuum construct is rarely mentioned elsewhere in the literature (4 of 30 of the sampled papers from the other B clusters; [38], a paper on birds, is a rarity in framing life history theory in similar terms to the papers from clusters B2 and B5). Moreover, the fast-slow continuum concept, at least under that name, was rare in the data up to and including 2010.…”