Christophe Tourenq

Are ricefields a good alternative to natural marshes for waterbird communities in the Camargue, southern France?

Abstract Rice cultivation has frequently been suggested to provide an important wetland habitat for waterbirds. However, in contrast to most other regions of the Mediterranean, the Camargue still has a substantial amount of surface area of natural marshes. Thus, we compared the abundance, species richness, and community composition of waterbirds in ricefields and natural marshes of the Camargue, during a one-year study. Based on surveys conducted at 4–7 day intervals in 1997–1998, our results suggest that natural marshes had substantially greater abundance of waterbirds, with ca. 99% of the individuals having been observed in natural marshes. Estimates of species richness and associated parameters further indicated that ricefields were clearly less rich than natural marshes. Although our results were rather striking for the Camargue, they may not be applicable to other regions because of the relatively high availability of natural marshes and differences in management of ricefields.

Effects of cropping practices on the use of rice fields by waterbirds in the Camargue, France

The abundance of waterbirds was compared in 46 rice fields in relation with the age of the field and the planting practices in spring. Of the 29 species censused, Charadriiformes represented some 73%, Ciconiiformes 6%, and Anseriformes less than 15.5% of the total number of individuals, flamingos and moorhens being also observed. Insectivorous species were the main component of the waterbird community. Bird numbers decreased with increasing field age and were lower in dry-sown than in wet-sown fields. The present results suggest that intensive and/or repetitive soil management and pesticide use may decrease the food resources available to waterbirds.

Foraging success and foraging habitat use by Cattle Egrets and Little Egrets in the Camargue, France

Abstract We examined habitat use by Little Egrets (Egretta garzetta) and Cattle Egrets (Bubulcus ibis) that nest together in mixed-species colonies in the Camargue of southern France. We explored the relative use of seven habitat types in relation to their availability and tested the hypothesis that selection of habitat types was related to foraging success, with the prediction that increased foraging success in a given habitat corresponded with increased use of that habitat type. Ricefields and other agricultural habitats were used more than expected by Cattle Egrets, an invasive species in southern Europe; whereas Little Egrets, which are native to the Camargue, tended to select natural freshwater marshes and lagoons. Results were consistent with the hypothesis that increasing use of habitats corresponded with higher foraging success for both species. However, when this analysis was restricted to habitats with sufficient numbers of birds to enable estimates of biomass intake, the association was no longer apparent for Little Egrets.

Variation in Parental Care with Offspring Age in the Greater Flamingo

Several studies have predicted how parental investment should change in relation to the age of offspring (Williams 1966, Winkler 1987). The Reproductive Value Hypothesis (RVH) states that parents should be prepared to invest more in older juveniles because they have a higher probability of surviving to breeding age. This may occur because older juveniles are closer to maturation and because the instantaneous rate of juvenile mortality generally decreases with increasing age (Clutton-Brock 1991). Increase in feeding effort with chick age has been documented for some species of colonial waterbirds. In Pigeon Guillemots (Cepphus columba) provisioning rates increased with chick age, only during the first part of the nestling period (Emms and Verbeek 1991). Feeding rates were not observed to vary with chick age in the closely related Black Guillemot (Cepphus grylle), but size of fish delivered to the nest increased with chick age (Cairns 1987). As chicks grow older they also have greater food requirements, and increased parental care might simply correspond to the higher energetics and nutritional demands of the offspring. Further evidence for increased parental care with increasing age of offspring comes from studies of brood defense. Brood defense has been reported to increase with nestling age in several passerine species (Andersson et al. 1980, Redondo and Carranza 1989, but see Knight and Temple 1986, Westmoreland 1989). However, the observed increase in parental care with offspring age can also be influenced by confounding variables such as parental age and or quality. Breeding success is known to increase with parental age in several bird species (Saether 1990) and this can be the result of increased experience with age. In addition, as parents grow older, their potential for future reproduction decreases. Thus the cost of reduced future reproductive success should decline with age and older parents should be selected to invest more in offspring compared to younger parents (Pugesek 1981). Therefore, it is important to control for parental age when considering variation in parental care with offspring age. Here, we analyze data from two years on the duration of feeding bouts by Greater Flamingo (Phoenicopterus ruber roseus) parents of known age and sex to their offspring. We show that only male parental care increases with offspring age. We discuss our results in relation to lifetime reproductive success and costs of reproduction.

Nesting, distribution and conservation of the Crab Plover, Dromas ardeola, in the United Arab Emirates

Abstract We studied the nesting and distribution of the Crab Plover, Dromas ardeola, in the United Arab Emirates through regular monitoring of colonies during the breeding season and counts at other key waterbird sites throughout the country during the non-breeding season. Based on counts of active nests, we estimate 1400–1500 breeding pairs of Crab Plovers in the United Arab Emirates at the two active colonies, accounting for over 30% of the Arabian breeding population. Discovery of a newly formed colony in 2004 and abandonment of the old colony on Abu Al Abyad demonstrate the potential of expansion of colonies in other areas. With breeding confirmed at only two islands in the Emirate of Abu Dhabi, from a conservation perspective this species is one of the most important breeding birds in the United Arab Emirates. Outside the breeding season, Crab Plovers congregate at few coastal sites in the country. Long-term conservation of Crab Plovers in the Emirates depends on the continued protection of the few breeding sites and urgent protection of the key sites used outside the breeding season.

Absence of Haematozoa in Chicks of Little Egret in the Camargue, Southern France

-High nest densities in colonial birds is assumed to favor the infection of individuals by parasites. Little Egrets (Egretta garzetta) chicks (N = 187) were sampled before nest departure in six different colonies of the Camargue, southern France, to determine the prevalence of Haematozoa infection. The absence of blood parasites is discussed. Received 8 August 2001, accepted 25 August 2001.

Nest Site Selection by Sooty Gulls on Jarnein Island, United Arab Emirates

Abstract Nest-site selection and nesting habitat use by the Sooty Gull (Larus hemprichii) was studied on Jarnein Island in the United Arab Emirates during the 2002 breeding season. Sooty Gull nests were located mainly on the north and northeast sides of the island. Birds showed definite preference for rocky substrates.