On 23 of May, in Pangrango NP, me and Santi came across with a Pygmy Tit’s nest ,Java’s smallest bird. With a length of 8 cm’s it surely deserves this distinction and name.
The Pygmy Tit (Psaltria exilis) is placed in the Aegithalidae family but his true relationships remain obscure. The genus Psaltria is endemic to Java and Bali.
Little is known about its breeding biology, and even nowadays the juvenile plumage remains undescribed, although is believed to be very similar to the adult plumage.
Around 1h15 pm we noticed activity around the nest and we took the opportunity to take some notes.
The nest is in a Rasamala tree, around 10 m from the ground. We could see it up close from a Canopy trail.
The nest structure is no more than moss coupled to an epiphyte. The bird took advantage of this structure to build the nest or could it be used as camouflage?
We noticed the birds joining mixed flocks to collect food and returning to the nest each time the flock passed at the area. Seicercus grammiceps and Phylloscopus trivirgatus were the main species on those flocks.
The only prey we saw being taken was small caterpillars.
In one occasion we saw 3 birds around the nest, bringing food. One of them entered into the nest and remained there, while the others were foraging. This strongly suggests cooperative breeding.
The time length between each visit was very long, 18 to 40 min.
We didn’t manage to get views of the nestlings, but they seemed very young, assuming from the noise coming from the nest.
The surrounding area is Primary forest (transitional from sub-montane to montane vegetation), composed mainly by tall Rasamala trees. The nest tree is located in a valley (around 1500 m elevation), with a fast flowing stream passing by.