Jongejans, E.

Since 2018, increasing number of dead juvenile flamingos were found on Bonaire. This study aims to determine what reproduction rate is required to keep the population stable or increasing, by constructing and analysing a population model. However, a literature search for estimates of the vital rates of the Caribbean flamingo shows that these are largely unknown or have a high degree of uncertainty. Clutch size is estimated to be 1, breeding success is estimated around 40%, juvenile and adult survival is estimated to be high, age of first reproduction is estimated to be 3 and the breeding chance is unknown. Usage of data from a ringing project in Yucatan, Mexico, could improve the estimates. A general ‘flamingo’ population model shows that annual population dynamics of flamingos is mainly determined by adult survival. Incidental years with low chick survival are therefore unlikely to have a large effect on a population. Thus far, the reason for the increasing number of dead juvenile flamingos found on Bonaire remains unknown. Additional information about the population in Venezuela is necessary for understanding the population dynamics on Bonaire, since flamingos frequently fly from and to the mainland.

Abstract:

Marine spatial population dynamics are often addressed with a focus on larval dispersal, without taking into account movement behavior of individuals in later life stages. Processes occurring during demersal life stages may also drive spatial population dynamics if habitat quality is perceived differently by animals belonging to different life stages. In this study, we used a dual approach to understand how stage-structured habitat use and dispersal ability of adults shape the population of a marine fish species. Our study area and focal species provided us with the unique opportunity to study a closed island population. A spatial simulation model was used to estimate dispersal distances along a coral reef that surrounds the island, while contributions of different nursery bays were determined based on otolith stable isotope signatures of adult reef fish. The model showed that adult dispersal away from reef areas near nursery bays is limited. The results further show that different bays contributed unequally to the adult population on the coral reef, with productivity of juveniles in bay nursery habitat determining the degree of mixing among local populations on the reef and with one highly productive area contributing most to the island’s reef fish population. The contribution of the coral reef as a nursery habitat was minimal, even though it had a much larger surface area. These findings indicate that the geographic distribution of nursery areas and their productivity are important drivers for the spatial distribution patterns of adults on coral reefs. We suggest that limited dispersal of adults on reefs can lead to a source–sink structure in the adult stage, where reefs close to nurseries replenish more isolated reef areas. Understanding these spatial population dynamics of the demersal phase of marine animals is of major importance for the design and placement of marine reserves, as nursery areas contribute differently to maintain adult populations.