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Brown Gerygone Nest
Like other Australian Warblers, the Brown Gerygone (Gerygone mouki) builds its nest in three stages. First, it makes a hanging, solidly interwoven mass of fiber bound with cobweb, gradually building it up to become longer and thicker.
Then it makes a hole in the side usually towards the top-which it hollows out and enlarges by shuffling and turning in the cavity; in the process, it pushes out the walls of the nest. Lastly, it roofs the entrance hole all around. The ultimate shape of the nest depends very much on the time spent in each of these stages. It is usually about 260-300 mm long, including the 75-120 mm ‘tail’.
The nesting and breeding months are September-February. Normally the bird builds a nest like a slender dome, with a long bulky tail and projecting side-entrance hood extended into a funnel; of soft-bark fiber, rootlets, grass, and moss bound firmly with cobweb, adorned with lichen or green moss; lined with soft plant down or, rarely, fur or feathers; slung from a slender stem among hanging branch lets or lawyer-vines in rainforest 5-15 meters above the ground level, often near water.
Diet
Like all Australian gerygones, the Brown gleans its insect food from leaves and branches but occasionally darts out like a flycatcher to capture insects on the wing, or takes them in flight while hovering with rapid wing beats about the outer foliage. While feeding it has a tendency to shake its wings and flick its tail.
Habitats
Brown Gerygones, from coastal New South Wales to northeastern Queensland, lack the sweet, sibilant song of the others. They also differ in that display between the sexes is more mutual. The birds bow slightly and delicately and fan their tails to reveal white spots at the tip. Only the female incubates, but both sexes-and sometimes additional helpers-feed the young. The bird is mostly found in mountain rainforests, wet gullies, and mangroves.
Identification
Both adults’ are alike. However, the upper parts are rich, deep olive-brown, often toned rusty, with a distinct white stripe on side of the forehead extending back towards but hardly over the eye. And indistinct white eye-ring, dark lores; cheeks grey finely scalloped with white.
Also, the wings as back, flight feathers grayer-brown. The tail is gray-brown, with a broad black bar near the tip and a distinct white spot at the inner tip of all tail feathers except the central pair. Underparts cream to soft grey on throat, neck, and breast, with or without red-brown wash on sides of the belly. The eye color is rich red-brown along with the black bill and the feet are deep olive-gray to black. The immature birds are like adults; their eyes are brown.
Eggs
Brown Gerygone bird laid two or three eggs; which are normally matt white to pink, freckled, spotted, and blotched with dull to bright red and purple-red, often in a zone at the larger end; oval, about 17 x 12 mm. The incubation period is about 17-19 days, apparently for a female. However, the young chick fledges in about 16-17 days.
Distribution
The distribution of this bird is cool, subtropical rainforests and their fringes in eastern coastal Australia and adjacent ranges to about 1200 m high, from near Cook-town, Queensland, south to Gipps-land, Victoria., and inland to Carnarvon Range. There are three races.
Size
The size of Brown Gerygone is approximately 95-115 mm in length.
Alternative Names
This bird is also known as Northern Warbler, Brown Fly-eater, Citron Bird, and Brown Warbler.
Status
The bird population is in large numbers but not quantified. Hence it is considered the least concern by the IUCN.
