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Han Olff - One of the best experts on this subject based on the ideXlab platform.
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large scale ecosystem engineering by Flamingos and fiddler crabs on west african intertidal flats promote joint food availability
Oikos, 2019Co-Authors: Elhacen Mohamed Elhacen, Tjeerd J Bouma, Puck Oomen, Theunis Piersma, Han OlffAbstract:Although the ecosystem engineering concept is well established in ecology, cases of joint engineering by multiple species at large scales remain rare. Here, we combine observational studies and exclosure experiments to investigate how co-occurring greater Flamingos Phoenicopterus roseus and fiddler crabs Uca tangeri promote their own and each other's food availability by creating a spatially complex mosaic of depressions (bowls, gullies) and hummocks (plateaus, mounds) in the intertidal zone. This results in a mosaic of microhabitats with different tidal inundation regimes. These microhabitats are spatially organized with labyrinth-like patterns in the high intertidal zone and spotted patterns in the lower intertidal, both of which likely arise from biophysical interactions between these organisms and hydrodynamic forces. We show that the resulting spatial complexity is vital for biofilm production. The depression microhabitats were wetter and richer in organic matter and biofilms compared with hummocks. Excluding Flamingos and crabs resulted in an increase in biofilm biomass over the shorter term (six months), but a decrease over the longer term (after one year). Moreover, our results strongly suggest that these biogeomorphological microhabitats in the mosaics were maintained by the feeding activities of Flamingos and to a lesser extent crabs. During a period of Flamingo exclusion, all the spotted patterns filled up with sediment, while the exclusion of crabs led to gradual sediment accumulation in the labyrinth-like patterns. Collectively, these findings provide empirical evidence for large-scale joint promotion of food availability by multiple taxa in a marine ecosystem.
Alan R. Johnson - One of the best experts on this subject based on the ideXlab platform.
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to leave or not to leave survival trade offs between different migratory strategies in the greater Flamingo
Journal of Animal Ecology, 2012Co-Authors: Ana Sanzaguilar, Alan R. Johnson, Arnaud Bechet, Christophe Germain, Roger PradelAbstract:Summary 1. The balance between costs and benefits of migration under different environmental, density-dependent and individual conditions may promote a broad range of migratory behaviours. We studied the factors influencing first-year migration and subsequent fidelity or dispersal among wintering areas, and the survival costs of different wintering behaviours in the greater Flamingo (Phoenicopterus roseus). 2. We analysed by multievent capture–recapture modelling among-site dispersal/fidelity and site-dependent survival probabilities from 22 671 Flamingos ringed in the Camargue (France) between 1977 and 2010 and resighted subsequently in their wintering grounds classified as France, Iberian Peninsula, Italy and North Africa. 3. We found that first- and second-year birds either resident or wintering at medium distances from their birth place, survived better than those wintering further afield. However, under severe winter conditions (extremely cold winter 1984–1985), individuals with the sedentary strategy suffered the highest levels of mortality. From the third winter onwards, the pattern of survival reversed: the long-distance wintering individuals (i.e. North Africa) survived better. 4. The proportion of first-year birds migrating for wintering was highly variable among cohorts and increased with favourable environmental conditions (wet years). After the first winter, birds showed high fidelity (>90%) to their previous wintering area and wintered preferably near their natal colony when they became adults (>2 years). 5. Survival estimates suggest that long-distance migration was costly for young and inexperienced individuals. Nonetheless, for adults, the most southern wintering areas seem to offer the most favourable local conditions for overwinter survival. 6. The higher availability of intermediate stopover sites during wet years may facilitate first-year migration. Then, once they have some wintering experience, Flamingos appear to favour the known wintering grounds. As they grow older, dispersing towards the vicinity of the natal colony may provide higher breeding prospects for individuals wintering closer to this high-quality and saturated breeding ground, as predicted by the arrival-time hypothesis.
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age assortative pairing in the greater Flamingo phoenicopterus ruber roseus
Ibis, 2008Co-Authors: Frank Cezilly, Christophe Tourenq, Vincent Boy, Alan R. JohnsonAbstract:Among long-lived bird species, the partners of breeding pairs are often of similar age. This pattern is largely influenced by little variation in the age at first breeding, linked with high survival rate and prolonged pair bonds. Contrary to other long-lived colonial species, Greater Flamingos Phoenicopterus ruber roseus do not show mate fidelity over consecutive breeding seasons. We studied pairing patterns of Greater Flamingos breeding in the Camargue, southern France, between December 1989 and March 1992. In each year, significant correlations were observed between the ages of the male and the female in a pair. The pattern of age-assortative mating was confirmed independently in each year by comparing the frequency distribution of age differences within pairs with the theoretical distribution derived from the age distribution of paired birds of known age in the population, assuming random pairing with respect to age. There was no evidence of a differential time of return each year to the colony with age. Analysis of display behaviour suggested that age-as-sortative mating in the Greater Flamingo results from a directional pairing preference for older and more experienced individuals. The present study provides direct evidence that age-assortative mating can occur independently of mate fidelity.
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anthropogenic and environmental determinants of greater Flamingo phoenicopterus roseus breeding numbers and productivity in the camargue rhone delta southern france
Ibis, 2007Co-Authors: Arnaud Bechet, Alan R. JohnsonAbstract:Predicting how bird populations may respond to climate change is a major challenge which could be addressed by understanding how past environmental processes have driven the variations of breeding population size and productivity. In inhabited regions, this issue may be complicated by the interference associated with heterogeneous levels of habitat management. Here, we have explored how several hydrological variables influenced the breeding of the Greater Flamingo Phoenicopterus roseus in the Camargue (Rhone delta, southern France) over a 28-year period (1974‐2001). In this region, Flamingos breed in a commercial salt pan. They forage in both salt pans and adjacent brackish lagoons. We hypothesized that breeding numbers, productivity and body condition of chicks at fledging were influenced positively by water levels of the Vaccares, the main lagoon of the delta, in spring (water and food availability) and the Rhone discharge in winter (nutrient availability in the salt pans). We controlled for variations of the flooding date of the breeding salt pan by the salt company and the size of the breeding island. We first found the Vaccares water levels and Rhone discharge to be negatively correlated with the North Atlantic Oscillation (NAO). Secondly, the number of Flamingo breeding pairs (range 3560‐22 200) increased by 1767 ± 1418 (95% CI) with a 10-day advance of the flooding date of the breeding salt pan and by 1146 ± 1081 per 10-cm water level rise in the Vaccares. Productivity was 0.46 ± 0.41 chicks per pair and could not be explained by any of the variables considered. Finally, chick body condition decreased with the number of breeding pairs and Rhone discharge. Our results show that (1) this intensely managed system remains sensitive to large-scale climate variations, (2) the breeding of the Greater Flamingo is affected by both climate variations and management of the salt pan, and (3) the expected enhancement of delta productivity by high river discharge was absent, probably prevented by dykes and embankments along the river. The response of bird populations to climate variations can thus be complex in intensely managed biological systems as found in the Mediterranean. We encourage pursuing such analyses incorporating anthropogenic variables explicitly in order to expand our capacity to make inference on the future of these systems.
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identifying rice fields at risk from damage by the greater Flamingo
Journal of Applied Ecology, 2001Co-Authors: Christophe Tourenq, Alan R. Johnson, Stephane Aulagnier, Laurent Durieux, Sovan Lek, Francois Mesleard, Jeanlouis MartinAbstract:Summary 1 Since the early 1980s, greater Flamingos Phoenicopterus ruber roseus have been reported to cause damage to the rice fields of the Camargue, south-eastern France. 2 We tested whether some rice fields had landscape features that were more attractive to Flamingos than others, using data from the period 1993–97 and from 1978 different paddies. Discriminant function analysis (DFA), logistic regression (LR) and artificial neural networks (ANN) were used to identify the environmental variables best explaining Flamingo incursions. 3 The most accurate models (LR) gave 75% prediction success and used as predictors the surface area of rice fields, the presence of contiguous damaged fields, the presence of wooded margins and the distance to natural marshes. 4 Our study suggests that it is possible to identify accurately fields at risk from damage in order to concentrate scaring methods. We also suggest that planting hedges should be promoted, and wood cutting discouraged, in high-risk areas. Following our study a programme of planting of hedges by the Natural Regional Park of the Camargue started at the beginning of 2000. 5 Our work reveals how presence–absence modelling can have clear applications in managing important species that sometimes cause negative impacts locally.
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Re‐mating between and within breeding seasons in the Greater Flamingo Phoenicopterus ruber roseus
Ibis, 1995Co-Authors: Frank Cezilly, Alan R. JohnsonAbstract:Data on re-mating between and within breeding seasons were collected between 1983 and 1994 as part of a long-term study of the Greater Flamingo Phoenicopterus ruber roseus in the Camargue, southern France. Flamingos have bred in the Rhône delta for centuries and since 1972 have done so annually on an artificial island in the Etang du Fangassier. A sample of chicks has been ringed each year since 1977; many of these birds were later observed back at the breeding site and were used in this study. The mate-switching rate between consecutive breeding seasons was 98.3%. This result is contrary to what has been reported from captive flocks where extensive mate fidelity occurred between consecutive breeding seasons. Mate-switching also was observed in the Camargue within breeding seasons, following breeding failure, and seems to be linked to male breeding strategy in response to the need to synchronize hatching and the limited energy supply of breeding females. The absence of a long-term pair bond in Greater Flamingos contrasts with current views on the evolution of mate fidelity in relation to longevity in birds.
Tjeerd J Bouma - One of the best experts on this subject based on the ideXlab platform.
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large scale ecosystem engineering by Flamingos and fiddler crabs on west african intertidal flats promote joint food availability
Oikos, 2019Co-Authors: Elhacen Mohamed Elhacen, Tjeerd J Bouma, Puck Oomen, Theunis Piersma, Han OlffAbstract:Although the ecosystem engineering concept is well established in ecology, cases of joint engineering by multiple species at large scales remain rare. Here, we combine observational studies and exclosure experiments to investigate how co-occurring greater Flamingos Phoenicopterus roseus and fiddler crabs Uca tangeri promote their own and each other's food availability by creating a spatially complex mosaic of depressions (bowls, gullies) and hummocks (plateaus, mounds) in the intertidal zone. This results in a mosaic of microhabitats with different tidal inundation regimes. These microhabitats are spatially organized with labyrinth-like patterns in the high intertidal zone and spotted patterns in the lower intertidal, both of which likely arise from biophysical interactions between these organisms and hydrodynamic forces. We show that the resulting spatial complexity is vital for biofilm production. The depression microhabitats were wetter and richer in organic matter and biofilms compared with hummocks. Excluding Flamingos and crabs resulted in an increase in biofilm biomass over the shorter term (six months), but a decrease over the longer term (after one year). Moreover, our results strongly suggest that these biogeomorphological microhabitats in the mosaics were maintained by the feeding activities of Flamingos and to a lesser extent crabs. During a period of Flamingo exclusion, all the spotted patterns filled up with sediment, while the exclusion of crabs led to gradual sediment accumulation in the labyrinth-like patterns. Collectively, these findings provide empirical evidence for large-scale joint promotion of food availability by multiple taxa in a marine ecosystem.
Theunis Piersma - One of the best experts on this subject based on the ideXlab platform.
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large scale ecosystem engineering by Flamingos and fiddler crabs on west african intertidal flats promote joint food availability
Oikos, 2019Co-Authors: Elhacen Mohamed Elhacen, Tjeerd J Bouma, Puck Oomen, Theunis Piersma, Han OlffAbstract:Although the ecosystem engineering concept is well established in ecology, cases of joint engineering by multiple species at large scales remain rare. Here, we combine observational studies and exclosure experiments to investigate how co-occurring greater Flamingos Phoenicopterus roseus and fiddler crabs Uca tangeri promote their own and each other's food availability by creating a spatially complex mosaic of depressions (bowls, gullies) and hummocks (plateaus, mounds) in the intertidal zone. This results in a mosaic of microhabitats with different tidal inundation regimes. These microhabitats are spatially organized with labyrinth-like patterns in the high intertidal zone and spotted patterns in the lower intertidal, both of which likely arise from biophysical interactions between these organisms and hydrodynamic forces. We show that the resulting spatial complexity is vital for biofilm production. The depression microhabitats were wetter and richer in organic matter and biofilms compared with hummocks. Excluding Flamingos and crabs resulted in an increase in biofilm biomass over the shorter term (six months), but a decrease over the longer term (after one year). Moreover, our results strongly suggest that these biogeomorphological microhabitats in the mosaics were maintained by the feeding activities of Flamingos and to a lesser extent crabs. During a period of Flamingo exclusion, all the spotted patterns filled up with sediment, while the exclusion of crabs led to gradual sediment accumulation in the labyrinth-like patterns. Collectively, these findings provide empirical evidence for large-scale joint promotion of food availability by multiple taxa in a marine ecosystem.
Michael Schagerl - One of the best experts on this subject based on the ideXlab platform.
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Lesser Flamingo as a Central Element of the East African Avifauna
Soda Lakes of East Africa, 2016Co-Authors: Lothar Krienitz, Barbara Mähnert, Michael SchagerlAbstract:The East African Rift Valley lakes host an avifauna that is rich in biodiversity and individual numbers. Some of the water bodies are known as ‘Flamingo lakes’. They are renowned places even for non-biologists and attract hundreds of thousands of tourists from all over the world. Two Flamingo species inhabit these lakes, the Greater and the Lesser Flamingo. The latter is classified as ‘near threatened’ by the IUCN. Flamingos, considered by birdlovers as a reincarnation of the mythic firebird Phoenix, play a key role in the circle of life in the harsh alkaline aquatic environments developed on the volcanic ashes of the African Rift Valley. We focus on the Lesser Flamingo, a flagship species of the East African avifauna, and provide information about the life cycle and phylogeny, feeding behaviour and inter-lake movements. Moreover, threats to the Flamingo populations, including possible reasons for infrequent mass mortalities, are discussed.
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Sudden Flamingo deaths in Kenyan Rift Valley lakes
Wildlife Biology, 2014Co-Authors: Nadja Straubinger-gansberger, Martin Gruber, Mary Nakabungo Kaggwa, Linda A. Lawton, Steve Omondi Oduor, Michael SchagerlAbstract:The East African Rift Valley Lakes Bogoria and Nakuru sometimes host around 75% of the world population of lesser Flamingos Phoeniconaias minor. In this area, mysterious Flamingo die-offs have occupied researchers for four decades. Recently, cyanobacterial toxins came into the fore as a possible explanation for mass mortalities because the main food source of lesser Flamingos is the cyanobacterium Arthrospira fusiformis. We took weekly samples from July 2008 to November 2009 from Lakes Nakuru and Bogoria and analyzed them by high performance liquid chromatography for microcystins. Monthly, samples were cross-checked using protein phosphatase inhibition assays with lower detection limits and additionally screened for polar toxins. During our study period, three Flamingo die-offs occurred at L. Bogoria and we were able to analyze tissues of 20 carcasses collected at the shoreline. No cyanotoxins were detected either in plankton samples or in Flamingo tissues. Accordingly, other reasons such as food composit...
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A detailed time series assessment of the diet of Lesser Flamingos: further explanation for their itinerant behaviour
Hydrobiologia, 2012Co-Authors: Mary N. Kaggwa, Steve Omondi Oduor, Martin Gruber, Michael SchagerlAbstract:We hypothesised that changes in nutritional composition and quality of the pelagic phytoplankton community influence the occurrence of Lesser Flamingo populations in two Kenyan saline–alkaline lakes, Nakuru and Bogoria. This was achieved by carrying out a detailed time series assessment of the phytoplankton community composition and nutritional components (carbohydrates, crude protein and lipids) from July 2008 to October 2009 on a weekly basis for each lake. Lesser Flamingos were estimated visually from the lake shore of the sampling sites. In Lake Nakuru, Lesser Flamingos had a significant positive relationship with lipids and Arthrospira biomass but a negative relationship with small cyanoprokaryotes. For Lake Bogoria, no significant differences were observed as the Arthrospira was available throughout the sampling period though the Flamingo numbers still fluctuated. We concluded that the nutritional composition and quality of the phytoplankton community influence the temporal and spatial abundance of Lesser Flamingos although other factors such as the prevailing environmental conditions may take precedence.