Fall In Pelican Population May Signal El Nino
A success story for endangered species seems to be in trouble it is though because of El Nino
This year the California brown pelican completely failed to breed at their Mexican nesting sites according to surveys. Scientists are being very cautious with the reason and are avoiding citing any one single cause for the decline in numbers of fuzzy headed baby pelicans. There was a similar drop however during a previous El Nino event.
Dr. Daniel Anderson of the University of California Davis has seen this phenomenon before and says other reasons could include habitat loss and overfishing of sardines. However this year’s decline is the biggest such drop in baby pelican numbers Dr. Anderson has seen in nearly 50 years.
El Nino has yet to be officially declared by scientists though there is a 78 per cent probability of some kind of climatic event occurring by the summer.
The behavior of pelicans suggest they are already responding to a developing El Nino this year and whilst the weather event has still to develop into its full blown format the behavior of birds certainly suggests that it is likely to happen.
How warm water hurts baby birds
El Nino is a natural weather event where cool water in the Eastern Pacific Ocean is displaced by warmer water which ends up disrupting the population of fish. During previous such events the Brown Pelican tracked the shifting food supply and flocked to a more northerly fishing ground according to the research.
More data is needed to link the decline in breeding to El Nino.
The small number of hatchlings indicate there is a lack of food for adults at their breeding ground in Baja. This year if the birds arrived at their breeding grounds at all, many simply abandoned their nests according to surveys.
The breeding numbers have sunk to about 1 per cent of their average.
Expect a rebound
Pelicans have a long life span and can breed for decades, so it is not such a major problem when breeding fails over a single year and is unlikely to have a significant impact on the population. However the effect of El Nino on fish populations could result in a second consecutive year of breeding failure for the pelican. The birds require between 100 to 150 pounds of fish per hatchling over a period of five months.
At one time the Brown Pelican was critically endangered and very close to extinction as a result of the effects of DDT on their eggs. In the 1960’s scientists realized the bird’s eggs were unusually thin and attributed it to the pesticide. After the United States banned DDT in the 1970’s the population recovered.
