PREDICTING POPULATION TRENDS OF THE BLACK-FACED SPOONBILL (PLATALEA MINOR)

Abstract

The global population of the Black-faced Spoonbill (Platalea minor) has increased steadily. We estimated global population growth rates of the Black-faced Spoonbill based on annual counts of wintering populations in East Asia between 1991/1992 and 2003/2004. The mean (±SD) annual growth rate was 1.13 ± 0.08. The estimated survival rate was 86.6 ± 9.3% based on the annual return rates of color-banded birds in Taiwan between 1998 and 2005. We predicted global Black-faced Spoonbill populations in 2003/2004–2013/ 2014 using a stochastic exponential model and showed the mean global population in 2013/2014 would exceed 4,000 ± 950. The probability of a global population decline to less than the 2003/2004 level is low (P = 0.06). If the 1991–2004 growth rate is sustained, the probability for the global population to increase to twice that of the 2003/2004 level is 0.98 and the predicted mean wintering population in Taiwan could exceed 2,000 in 2013/ 2014. Establishment of new protective areas and increasing food availability at existing reserves and adjacent fish ponds in southwestern Taiwan will be necessary to ensure continued growth.