Dunnock of "braun", "brown", and the specific "modularis" is from Latin "modulus", "melody". A European robin-sized bird, the dunnock typically measures 13.5–14 cm in length. It possesses a streaked back, somewhat resembling a small house sparrow. Like that species, the dunnock has a drab appearance which may have evolved to avoid predation. It is brownish underneath, and has a fine pointed bill. Adults have a grey head, and both sexes are similarly coloured. Unlike any similar sized small brown bird, Dunnocks exhibit frequent wing flicking, especially when engaged in territorial disputes or when competing for mating rights. Dunnocks are native to
Common ostrich is scarce in dry and hot environment, and this poses a challenge to the ostrich's water consumption. Also the ostrich is a ground bird and cannot fly to find water sources, which poses a further challenge. Because of their size, common ostriches cannot easily escape the heat of their environment; however, they dehydrate less than their small bird counterparts because of their small surface area to volume ratio. Hot, arid habitats pose osmotic stress, such as dehydration, which triggers the common ostrich’s homeostatic response to osmoregulate. The common ostrich is well adapted to hot, arid environments through specialization of excretory