incubation period, the male will stand guard and protect the female and eggs while she incubates them for 25–31 days. The clutch (group of eggs) size fluctuates, with an average clutch size being between 6-14 eggs. The laying of each egg is done in approximately 24-hour intervals with laying occurring early in the morning. If a pair loses a brood (amount of chicks hatched at the same time) they will then begin to lay again only after a few weeks. Therefore, some pairs may lay several clutches per season. However, on average the grey teal will lay approximately two broods per season. Female grey teal will brood young by themselves, however, when necessary (e.g. death of the female) the male will take over the brooding role and raise the ducklings. Male will also often be present at the later stages of brooding as the female will return to incubate/lay her next clutch. After hatching, parents and broods may remain close to each other for a number of weeks; once the young gains flight it then becomes independent. However, siblings will often stick together for a short amount of time once they have left home. Fledging usually occurs between 35 and 40 days. Before that ducklings are grey-brown with off-white cheeks and underpart. For juveniles, both female and male grey teal become reproductively mature at one-year-old. Therefore the forming of a pair-bonding will commonly occur in the first winter. Song The call of the grey teal can be heard as a that is relatively rapid and includes a sharp whistle. The male and female calls are different in terms of volume and type. The male's call tends to be more of a whistle, whereas the female's call is very loud and harsh sounding. For short-distance communication, the birds have a softer variation of their calls. The grey teal's voice is very similar if not identical to the voice of a chestnut teal. Migration For migratory birds living in stable temperate areas, day length and temperature bring migration about by triggering hormonal changes. However, for birds living in a stochastic environment where resources are often temporary (e.g. grey teal Anas gracilis) hormonal control is less likely to allow good exploitation of resources hence allowing the survival of the species. In this type of environment birds have to be able to detect resourceful locations and relocate, meaning they have to move all year