Hervé Lormée

Endocrine Correlates of Parental Care in an Antarctic Winter Breeding Seabird, the Emperor Penguin,Aptenodytes forsteri ☆

Plasma levels of luteinizing hormone (LH) and prolactin associated with parental behavior were measured in the Antarctic winter breeding emperor penguin, Aptenodytes forsteri. Males exclusively incubate the egg while females exclusively brood the nonhomeothermic young; both sexes alternate in rearing the homeothermic young. Birds were sampled on arrival from the sea through egg laying, incubation, and brooding. All parent birds lost their chicks at the end of the brooding period due to harsh weather but sampling continued. In females, LH titers dropped after egg laying but levels were restored when the birds returned from the sea to brood the chicks and were not depressed by high prolactin levels. Plasma prolactin remained low in males captured on arrival and kept until the free-living males finished incubation. In breeders, prolactin secretion increased during the prelaying period when day length decreased. Prolactin levels stayed elevated in males during incubation and in brooding females returning after a 2-month absence at sea. Prolactin values were higher in brooding females than in males ending incubation or returning in late brooding. These levels did not drop after chick loss, and the sexual difference in prolactin values was maintained after breeding failure. In emperor penguins, increased prolactin secretion appears to be triggered around the time of egg laying and continues, driven by an endogenous mechanism, through incubation and brooding until rearing is completed. Prolactin secretion independent of external stimuli may have evolved in pelagic seabirds to maintain parental care despite long absences at sea from the breeding colony.

Kidnapping of chicks in emperor penguins: a hormonal by-product?

SUMMARY The function and causes of kidnapping juveniles are little understood because individuals sustain some breeding costs to rear an unrelated offspring. Here we focus on the proximal causes of this behaviour in emperor penguins (Aptenodytes forsteri), whose failed breeders often kidnap chicks. We experimentally tested the hypothesis that kidnapping behaviour was the result of high residual levels of prolactin (PRL), a hormone involved in parental behaviour. Penguins with artificially decreased PRL levels by bromocriptine administration kidnapped chicks less often than control penguins. Within the bromocriptine treated group, kidnapping behaviour was not totally suppressed and the probability of kidnapping a chick was positively correlated to PRL levels measured before treatment. During breeding, emperor penguins have to forage in remote ice-free areas. In these birds, PRL secretion is poorly influenced by chick stimuli and has probably evolved to maintain a willingness to return to the colony after a long absence at sea. Therefore, penguins that have lost their chick during a foraging trip still maintain high residual PRL levels and this, combined with colonial breeding, probably facilitates kidnapping. We suggest that kidnapping in non-cooperative systems may result from a hormonal byproduct of a reproductive adaptation to extreme conditions.

PATTERNS OF PROLACTIN SECRETION IN RELATION TO INCUBATION FAILURE IN A TROPICAL SEABIRD, THE RED-FOOTED BOOBY

Abstract Prolactin levels rapidly drop after breeding failure in several terrestrial bird species, but in penguins prolactin secretion can be maintained well after failure. We measured prolactin secretion in relation to reproductive failure in a tropical seabird, the Red-footed Booby (Sula sula). Incubation failure was recorded in 7 nests (2 accidental losses, 5 desertions). Prolactin titers significantly decreased after incubation failure. In birds that accidentally lost their egg, prolactin titers declined but measurements 12 to 24 hr after failure were still above basal levels. Birds naturally deserting their egg exhibited prolactin titers typical of basal levels 6–24 hr after abandonment. Two birds showed lower prolactin concentration as early as 4–8 days before nest desertion, suggesting that a decline in prolactin levels may precede egg desertion. This study shows that in this tropical seabird, incubation failure results in a rapid cessation of prolactin secretion, as it does for terrestrial birds. Relación entre los Niveles de Prolactina y el Fracaso Reproductivo en un Ave Marina Tropical, Sula sula Resumen. Los niveles de prolactina de varias especies de aves terrestres disminuyen rápidamente después del fracaso reproductivo. Sin embargo, en los pingüinos la secreción de prolactina tiende a mantenerse inalterada después del fracaso reproductivo. Medimos los niveles de prolactina en relación al fracaso reproductivo en un ave marina tropical, Sula sula. Se observaron 7 eventos de fracaso reproductivo (2 pérdidas accidentales de huevos y 5 deserciones de nidos). En general, los niveles de prolactina disminuyeron significativamente después del fracaso reproductivo. En las aves que perdieron accidentalmente sus huevos, los niveles de prolactina disminuyeron, pero las medidas registradas 12 a 24 horas después del fracaso fueron superiores a los niveles basales. Los niveles de prolactina de individuos que espontáneamente abandonaron sus nidos, medidos 6 a 24 horas después del abandono, fueron similares a los niveles basales. Dos individuos presentaron concentraciones de prolactina bajas 4 a 8 días antes del abandono de sus nidos, sugiriendo que una disminución del nivel de prolactina podría preceder el abandono de los nidos. Este estudio demuestra que el fracaso de incubación de esta especie de ave marina tropical conlleva a una rápida cesación de la secreción de prolactina, tal como ha sido observado en las aves terrestres.

Migration Routes and Staging Areas of Trans-Saharan Turtle Doves Appraised from Light-Level Geolocators

The identification of migration routes, wintering grounds and stopover sites are crucial issues for the understanding of the Palearctic-African bird migration system as well as for the development of relevant conservation strategies for trans-Saharan migrants. Using miniaturized light-level geolocators we report a comprehensive and detailed year round track of a granivorous trans-Saharan migrant, the European Turtle Dove (Streptopelia turtur). From five recovered loggers, our data provide new insights on migratory journeys and winter destinations of Turtle Doves originating from a breeding population in Western France. Data confirm that Turtle Doves wintered in West Africa. The main wintering area encompassed Western Mali, the Inner Delta Niger and the Malian/Mauritanian border. Some individuals also extended their wintering ranges over North Guinea, North-West of Burkina Faso and the Ivory-Coast. Our results reveal that all individuals did not spend the winter period at a single location; some of them experienced a clear eastward shift of several hundred kilometres. We also found evidence for a loop migration pattern, with a post-breeding migration flyway lying west of the spring route. Finally, we found that on their way back to breeding grounds Turtle Doves needed to refuel after crossing the Sahara desert. Contrary to previous suggestions, our data reveal that birds used stopover sites for several weeks, presumably in Morocco and North Algeria. This later finding is a crucial issue for future conservation strategies because environmental conditions on these staging areas might play a pivotal role in population dynamics of this declining species.

Population Survey of Leach's Storm-Petrels Breeding at Grand Colombier Island, Saint-Pierre and Miquelon Archipelago

Abstract The St Pierre and Miquelon Archipelago hosts the only French Leachs Storm-Petrel (Oceanodroma leucorhoa) colony. We conducted a survey during the 2008 breeding season to estimate the breeding population size on Grand Colombier Island. This survey included an estimation of burrow detection probability using a double-observer approach. We estimated that 3% of Leachs Storm-Petrels nests had failed before we started the survey. Nest occupancy probability was neither affected by slope nor vegetation type and was 0.546 ± 0.029. Burrow density was positively affected by slope and, consequently, was much lower on the plateau than on island slopes. Burrow detection probability was neither affected by observer nor by habitat and was 0.89 ± 0.01. We estimated the population to be 363,787 [95% CI  =  295,502–432,072] breeding pairs, which is among the largest Leachs Storm-Petrel colonies in the northwestern Atlantic Ocean.

Turtle Dove Streptopelia turtur migration routes and wintering areas revealed using satellite telemetry

ABSTRACT Satellite telemetry of two European Turtle Doves Streptopelia turtur confirmed the broad patterns suggested by earlier work using geologgers but also revealed that they migrated by night and used four distinct stopover and two wintering sites. Winter habitat used by one bird covered less than 100 km2 per site, much smaller than previously assumed.

Effects of the February 2012 cold spell on terrestrial birds wintering in France

We document the mortality of terrestrial bird species wintering in France as a result of the 2012 February cold spell. We describe the range of species affected and how some of them reacted to the cold spell in term of movement and variation in body mass. Mortality records concerned 1,791 individuals from 42 species. Among terrestrial birds, Northern Lapwings Vanellus vanellus, Eurasian Woodcocks Scolopax rusticola and thrush species suffered the most from the cold spell. Among casualties, 56% of birds starved to death and 8.4% were predated. Collisions with vehicles accounted for 23.7% of deaths for all species, and reached 50% for Lapwings. Location of mortality records suggested that Lapwings and Woodcocks moved en masse towards the south and southwest of France to escape from the cold spell. Body mass of thrushes, Lapwings and Woodcocks birds was rapidly depleted because birds could not access food resources. On average, birds which were 30% lighter than birds weighed at the same period during normal winters had reached a lethal body mass. The results of this enquiry highlight the impact of such cold-weather events and the need, in particular for game bird species, to promote standardised enquiries on mortality when severe winter events occur.