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.
Bonaire is home to the largest natural flamingo reserve in the western hemisphere, housing one of the four remaining crucial breeding grounds in the world and the primary breeding ground of the Americas. Flamingos filter feed on gastropods, crustaceans and chrinomids in salt water lakes and ponds. This study examined flamingo distribution and feeding behavior in relation to changing salinity levels in condenser ponds used for salt production on Bonaire, Netherland Antilles. Flamingo density was found to be highest (44.4-172.7birds/km2 ) in ponds with the highest salinity (184-205g/l) among the ponds tested, followed by ponds with the lowest salinity (55 g/l). Ponds with an intermediate salinity (84-154 g/l) hosted significantly fewer birds (0-1.6 birds/km2 ). The type of feeding behavior used by flamingos was found to be related to water depth and salinity range and could possibly be explained by differences in prey found at different salinities and depths; however, this specific question was only addressed in a qualitative manner in this study. Grubbing was most prevalent in high salinity ponds while skimming occurred with higher frequency in low salinity ponds. Because grubbing is generally used to feed on pond bottoms results suggest that prey items in high salinity ponds may be densest at the bottom and probably consist of chrinomids such as brine fly pupae. Conversely, skimming is used in shallower water and its prevalence in low salinity ponds indicates that prey is concentrated in the water column and best caught by filter feeding mechanisms.
This student research was retrieved from Physis: Journal of Marine Science III (Spring 2008)19: 1-5 from CIEE Bonaire.
In 2010 a petrochemical fire took place at the BOPEC oil terminals on Bonaire. These facilities are located on the shores of the Goto lake, a legally protected RAMSAR wetland and important flamingo foraging area. Before the fire, daily flamingo counts averaged approximately 400 birds that used the area to feed on Artemia (brine shrimp) and Ephydra (brine fly larvae). Immediately after the fire, flamingo densities plummeted to nearly none and have not recovered. A large amount of fire retardants were used to combat the fire, and were hypothesised to be a potential cause for the flamingo declines. Our analyses of 15 years of baseline flamingo monitoring data show that rainfall does influence flamingo densities but only on the short-term and steering seasonal dynamics of flamingos. Therefore the rainfall event/change in the rainfall regime cannot account for lasting absence of flamingos. Nearby control lakes that were not affected by the fire showed no lasting reduction in flamingo densities, but instead an increase due to the birds no longer feeding in Goto.
In 2012, we measured the concentrations of polycyclic aromatic hydrocarbons (PAHs) and perfluorinated compounds (PFCs, which includes PFOS) in Goto and control-lake waters and conducted additional chemical screening (fingerprinting) of sediments and biota. These measurements showed both lasting elevated levels of PFCs, in water, sediments and biota (fish) and lowered food-species concentrations in Goto as compared to control areas. Based on calculated Risk Quotients combined with the chronic exposure, for the documented PFOS levels, toxicological effects on benthic organisms such as Artemia and Ephydra are likely. Nevertheless additional impact by other associated retardant toxicant is also probable. Goto was found to be chemically different based on GC*GC chemical fingerprinting indicative of elevated Butylated Hydroxytoluene (BHT) concentrations, a compound used in petrochemical industries as a solvent.
In conclusion, our results demonstrate a close link between the 2010 Bopec fires and the subsequent abandonment of the adjacent Goto lake by foraging flamingos. Compared to nearby control lakes, Goto was found to have elevated (and toxic) concentrations of PFCs and associated low food species concentrations. Therefore, our results suggest that the lasting abandonment of the lake by flamingos after the fire have been due to the drastically low food-species densities as likely caused by toxic ecosystem effects resulting from retardants released into the environment while combatting the fires.