Early‐life foraging: Behavioral responses of newly fledged albatrosses to environmental conditions

Abstract

In order to survive and later recruit into a population, juvenile animals need to acquire resources through the use of innate and/or learnt behaviors in an environment new to them. For far‐ranging marine species, such as the wandering albatross Diomedea exulans, this is particularly challenging as individuals need to be able to rapidly adapt and optimize their movement strategies in response to the highly dynamic and heterogeneous nature of their open‐ocean pelagic habitats. Critical to this is the development and flexibility of dispersal and exploratory behaviors. Here, we examine the movements of eight juvenile wandering albatrosses, tracked using GPS/Argos satellite transmitters for eight months following fledging, and compare these to the trajectories of 17 adults to assess differences and similarities in behavioral strategies through time. Behavioral clustering algorithms (Expectation Maximization binary Clustering) were combined with multinomial regression analyses to investigate changes in behavioral mode probabilities over time, and how these may be influenced by variations in day duration and in biophysical oceanographic conditions. We found that juveniles appeared to quickly acquire the same large‐scale behavioral strategies as those employed by adults, although generally more time was spent resting at night. Moreover, individuals were able to detect and exploit specific oceanographic features in a manner similar to that observed in adults. Together, the results of this study suggest that while shortly after fledging juvenile wandering albatrosses are able to employ similar foraging strategies to those observed in adults, additional skills need to be acquired during the immature period before the efficiency of these behaviors matches that of adults.

Divergent foraging strategies during incubation of an unusually wide-ranging seabird, the Murphy’s petrel

“…It uses the distributions of the two input variables to partition locations and identify thresholds for slow and fast movements, and for low (shallow angles) and high (wide angles) values of turning. Wide turning angles between locations are generally considered to be associated with ARS behaviour, while high speeds and straight tracks are typical of fast, directed movement (Garriga et al 2016; de Grissac et al 2017; Diop et al 2018). We differentiated between four different behaviours, namely directed movement (high speed, shallow angles), resting on the water (low speeds, shallow angles; inclusive of sit-and-wait feeding), and intensive (low speeds, wide angles) and extensive searching (high speeds, wide angles) (see Table S1 in supplementary material) (Louzao et al 2014; Garriga et al 2016).…”

Linking demographic processes and foraging ecology in wandering albatross—Conservation implications

“…Foraging movement capacities become similar to those of adults within a few months after fledging (Riotte‐Lambert & Weimerskirch, ). Individuals are also able during this short period to use efficiently wind conditions and detect environmental gradients (De Grissac, Bartumeus, Cox, & Weimerskirch, ). Juvenile survival over the first 2 years of life is 0.64, which is one of the highest values of early‐life survival estimated for a bird species, but still lower than annual adult survival (Figure ).…”

High mortality rates in a juvenile free‐ranging marine predator and links to dive and forage ability

“…In many species, these need to develop rapidly, as individuals quickly transition from full parental care and provisioning to complete independence (Breed, Bowen, & Leonard, 2013;Costa, 1991;Reiter, Stinson, & Boeuf, 1978). The first trip made at sea alone may thus prove a critical time for survival, as individuals must either learn, learned, or have inherited advanced dive and forage abilities so as to be able to exploit the large heterogeneous environments typically inhabited (Carter et al, 2017;de Grissac, Bartumeus, Cox, & Weimerskirch, 2017;Orgeret et al, 2016;Riotte-Lambert & Weimerskirch, 2013). This may include physiological capability and foraging efficiency, knowledge of habitats and prey distribution, alongside predator avoidance strategies.…”