The Best Place to Watch Shorebirds in Celebes Coast

The best place to watch shorebirds in Celebes Coast.

In addition to the waders, other common large birds of the coast include the white-bellied sea eagle (Heliacetus leucogaster), the osprey (Pandion haliatus) and Brahminy kite (Haliastur Indus) all of which fish in the shallow waters and scavenge food along undisturbed beaches. There also various stork, herons, egrets and ducks seen around the shore and roosting sites for seeing these birds (Uttley 1986). The milky stork (Ibis cinereus) is of particular interest because until a few years ago it was though to be quite rare. Large numbers have now been found in Sumatra (Silvins et al. 1985) and they have also been observed, some in breeding plumage, in the Tiworo straits between Muna island and the mainland of southeast Celebes (L. Clayton pers. Comm..), near Ujungpandang and in the Cenrara River delta (Uttley 1986).


Such fish-eating birds might occasionally encounter venomous sea snakes in the shallow waters of mudflats. One species, the yellow-bellied sea snake (Pelamis platurus), is the most widely distributed species of snake, being found from south Siberia to Tasmania, and from the west coast of America to the Indian Ocean. It is about I m long and is often found near the water surface and eats mainly rabbitfish and mulletlike fish (voris and voris 1983). Young, hand-reared with and without their tails. The tails of sea snakes are very distinctive. The birds were most frightened by the yellow-bellied sea snake, even if its tail had been removed. This indicates a genetically-based response; they could not have learned that the snake was dangerous from experience (Caldwell and Rubinoff 1983).

Bibliography
Grant, . 1984. sediment microtopography and shorebird foranging. Mar. ecol. Prog.

Barnard, C.J. and Thompson, D.B.A. 1985. Gulls and Plovers: the ecology of mixed species feeding groups. London Croom Helm.

Uttley, J. 1986. survey of Sulawesi Selatan to asses the status of wetlands and to identify key sites for breeding and migratory waterbirds. Preliminary report, Kuala Lumpur

Voris, H.K. and voris, H.h. 1983. Feedign strategies in marine snakes : an analysis of evolutionary, morphological, behavioural and ecological relationships. Amer. Zool.

Caldwell, G.S. and Rubinoff, R.W. 1983. Avoidance of venomeous sea snakes by naïve herons and egrets . Auk 100: 195-198

The Behavior Shorebirds

The behavior Shorebirds on mudflat in along Celebes coast
The penetrability of a beach sediment depends on its water content. This may be reason that some shorebirds can be seen running along the water’s edge on the ebbing tide pushing their bills into the thixotropic (fluid) sand. A careful examination of bill marks made in tidally formed sand ripples by dowitchers, a wading bird similar to godwits, showed that more marks were found on the crests than in the water-logged troughs.

Neither the distribution of prey nor sediment grain size showed only difference between crests and troughs, but penetrating the crests required only 50%-70% of the force required to penetrate the troughs. Thus, concentrating effort on the crests reduce energy expenditure. Ripple crests are sites of active sediment transport and the arrangement of the grains is relatively unstable. This larger volume of pore space allows a higher water content and offers less resistence to penetration. Although the differences in water content between crest and trough are small, minor differences in pore volume can produce major changes in the reaction of sand grains to a shearing force (Grant 1984).

Wading birds are often seen in mixed-species flocks which might be thought to be disadvantageous to the individuals by virtue of increased competition. In fact, more often than not, the birds are taking different foods and being together has the advantage that the more birds present the more likely it is that a predator, such as a bird of prey, will be seen. One particular species is usually first to settle on a certain stretch of beach having used visual clues to make its choice. Other species follow when it is clear that food is being found. A few species act as pirates taking food have to spend more time feeding to compensate for the loss, but here are advantages in that feeding birds have their heads down searching for food whereas the pirates generally keeps its head up and serves an early warning of the approach of predators (Barnard and Thompson 1985).