Age, sex, and breeding status shape a complex foraging pattern in an extremely long-lived seabird.

Evidence of age-dependent changes in foraging behavior of free-ranging individuals is scarce, especially at older stages. Using the isotopic niche as a proxy of the trophic niche during both the breeding (blood) and inter-nesting (feather) periods, we report here empirical evidence for age-, gender-, and breeding status-dependent foraging ecology and examine its potential consequences on subsequent reproduction and survival in an extremely long-lived species, the Wandering Albatross (Diomedea exulans). Immature Wandering Albatrosses of both sexes forage in the subtropics (delta13C) and feed at the same trophic position (delta15N) as the adults. In contrast to immature birds, adult females forage, on average, at more northern latitudes than males, with both sexes feeding in the subtropics during the internesting period, and males, not females, favoring subantarctic waters during incubation. In contrast to adult females, males show a unique pattern among birds and mammals of a continuous change with age in their main feeding habitat by foraging progressively farther south in colder waters during both the breeding and inter-nesting periods. In males, foraging at higher latitudes (lower feather delta13C values) is associated with a lower probability of breeding during the following years compared to other birds, but with no effect on their probability of surviving. Foraging in cold and windy waters may be linked to foraging impairment that might explain different life history trade-offs and lower investment in reproduction with age. This key point requires further longitudinal investigations and/or studies examining foraging success and the energy budget of birds feeding in different water masses.

Oxidative stress in relation to reproduction, contaminants, gender and age in a long-lived seabird.

Reproduction is a demanding activity for animals, since they must produce, and in some cases protect and provision, their young. It is often overlooked that demands of reproduction may also be exacerbated by exposure to contaminants. In this study, we make use of an exceptional long-term dataset to perform a cross-sectional study on the long-lived wandering albatross (Diomedea exulans) in order to test the effects of reproduction, persistent organic pollutants [POPs: pesticides and polychlorinated biphenyls (PCBs)], mercury, individual age (3-47 years), and sex on the levels of plasma oxidative damage and inflammation. The results of our study support the hypothesis that oxidative damage may be a physiological cost of reproduction and that individuals carrying higher levels of organic or non-organic contaminants have higher oxidative damage. Levels of the inflammatory protein haptoglobin were similar between breeding and non-breeding birds, with the exception of breeding males which had the lowest levels of haptoglobin. Our data also show an effect of age and of organic contaminants on the plasma oxidative damage level, but not on plasma haptoglobin. In addition, plasma oxidative damage level increased with red blood cell mercury concentration in females but not in males. Hence, our study highlights that the harmful effects of contaminants may come through interaction with factors like life stage or gender, suggesting potential for high variation in susceptibility to contamination among individuals.

Seabird satellite tracking validates the use of latitudinal isoscapes to depict predators' foraging areas in the Southern Ocean.

Stable isotopes are increasingly being used to trace wildlife movements. A fundamental prerequisite of animal isotopic tracking is a good knowledge of spatial isotopic variations in the environment. Few accessible reference maps of the isotopic landscape ("isoscapes") are available for marine predators. Here, we validate for the first time an isotopic gradient for higher trophic levels by using a unique combination of a large number of satellite-tracks and subsequent blood plasma isotopic signatures from a wide-ranging oceanic predator. The plasma δ(13)C and δ(15)N values of wandering albatrosses (n = 45) were highly and positively correlated to the Southern Ocean latitudes at which the satellite-tracked individuals foraged. The well-defined latitudinal baseline carbon isoscapes in the Southern Ocean is thus reflected in the tissue of consumers, but with a positive shift due to the cumulative effect of a slight (13)C-enrichment at each trophic level. The data allowed us to estimate the carbon isotopic position of the main oceanic fronts in the area, and thus to delineate robust isoscapes of the main foraging zones for top predators. The plasma δ(13)C and δ(15)N values were positively and linearly correlated, thus suggesting that latitudinal isoscapes also occur for δ(15)N at the base of the food web in oceanic waters of the Southern Ocean. The combination of device deployments with sampling of relevant tissues for isotopic analysis appears to be a powerful tool for investigating consumers' isoscapes at various spatio-temporal scales.

Patterns of aging in the long-lived wandering albatross.

How does an animal age in natural conditions? Given the multifaceted nature of senescence, identifying the effects of age on physiology and behavior remains challenging. We investigated the effects of age on a broad array of phenotypic traits in a wild, long-lived animal, the wandering albatross. We studied foraging behavior using satellite tracking and activity loggers in males and females (age 6-48+ years), and monitored reproductive performance and nine markers of baseline physiology known to reflect senescence in vertebrates (humoral immunity, oxidative stress, antioxidant defenses, and hormone levels). Age strongly affected foraging behavior and reproductive performance, but not baseline physiology. Consistent with results of mammal and human studies, age affected males and females differently. Overall, our findings demonstrate that age, sex, and foraging ability interact in shaping aging patterns in natural conditions. Specifically, we found an unexpected pattern of spatial segregation by age; old males foraged in remote Antarctica waters, whereas young and middle-aged males never foraged south of the Polar Front. Old males traveled a greater distance but were less active at the sea surface, and returned from sea with elevated levels of stress hormone (corticosterone), mirroring a low foraging efficiency. In contrast to findings in captive animals and short-lived birds, and consistent with disposable soma theory, we found no detectable age-related deterioration of baseline physiology in albatrosses. We propose that foraging efficiency (i.e., the ability of individuals to extract energy from their environment) might play a central role in shaping aging patterns in natural conditions.

Versatile use of hindered oxalates for the stereoselective preparation of novel 11-modified androst-5-ene derivatives.

The 11alpha- and 11beta-modified androst-5-ene derivatives 3a,b as well as the exo- and endocyclic dehydrated compounds 4a-c and 5b-c were produced using the oxalate derivatives of the highly hindered 11beta-hydroxyandrost-5-enes 1a-c. The 11-tetrahydrofuran derivative 6 was produced for the first time with good diastereoselectivity by an intramolecular 5-exo cyclization under radical conditions from the corresponding oxalate as precursor.

Are the 11-oxo-steroids really so hindered towards organometallic compounds?

Allylation of an 11-oxo-steroid, the protected adrenosterone, was studied to examine more closely the steric hindrance of such a ketosteroid. While the beta face exhibits, as well known, a strong steric hindrance, the alpha side appears to be only relatively hindered. A high diastereoselectivity was observed in the addition of crotyl magnesium bromide.