Grey Teal

46 cm

Mating/Breeding behaviours When establishing a pair-bond male Grey Teal will perform a series of displays, some of these include headshakes and head rolls . These displays tend to occur in adolescent birds before breeding season, whereas for mature birds in established pair-bonds courtship rituals are used . This is because Grey Teal pair-bonds are long term and monogamous . Meaning Grey teal keeps the same mate through seasons. Couples stay together all year however, when late summer moult comes they often join large flocks and stay with them until July . Moreover, “after breeding, [they] often gather at estuaries to feed on exposed mudflats” . On average, Grey teal starts breeding at one year old. In Australia there is no reproductive season as breeding is linked to rainfall and food abundance . The species had to adapt and breed in shallow temporary water. However, in New Zealand where the climate is more humid, breeding is more seasonal even if it is still related to water level. In terms of seasonality, Grey Teal will tend to breed in the summer-rainfall period . However, they will also breed at any time after a significant amount of rainfall . Thus, in New Zealand laying occurs between June and September “but replacement clutches can be laid through to January” . Therefore, their breeding time often shows seldom seasonal pattern . Nesting Nesting is usually solitary for Grey Teal; however, sometimes nesting sites will be close together, meaning breeding pairs may be close to one and other . Nests are often found in tree hallows or hidden amongst vegetation on the ground . Grey Teal is not known to construct nests other than using material found from its nesting site : grass and down . The female birds will create a bowl in the ground that they will proceed to fill with litter found from around the site as well as surround the nest/bowl with down (feather plumage). Between 1-7 eggs will be laid in a nest at a time . The nesting time occurs between the months of June-Feb in South Australia and slightly later in the area of North Australia due to a slight difference in temperature. Whereas in New Zealand Grey Teal tends to nest between the months of September-November . Egg Laying During the incubation period, the male Grey Teal will stand guard and protect the female and eggs while she incubates them for 25-31 days . The clutch (group of eggs) size of Grey Teal fluctuates with an average clutch size being between 6-14 eggs . Laying of each egg is done in approximately 24-hours intervals with laying occurring early in the morning . If a pair losses a brood (amount of chicks hatched at the same time) they will then begin to lay again only after a few weeks of this loss. Therefore, some pairs may lay several clutches per season . However, on average grey teal will lay approximately two broods per season . 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 round and do not have a migration season. Grey teal is a great avian nomad that flies long distances. It “is often the exemplar avian nomad in analyses movement and migration”. Thus, Roshier, D., Asmus, M., from Institute of Land, Water & Society, Charles Sturt University, Australia and Klassen, M., from Department of Plant-Animal interaction Netherlands Institute, Netherlands, led a study about the long-distance movements of Grey teal in Australia. Their goal was to determine what drives these long-distance flights. They found out that 13 out of 32 long-distance movements (> 150km) recorded were due to rainfall and/or flooding events that occurred up to 1050km from where the ducks initially were. Thus, it seems that water resources are a major reason in explaining the movements of Grey teal. However, some birds moved to other wetlands without clear beneficial reasons. So, according to Roshier, D., Asmus, M., & Klassen, M., there are two types of movements: ranging – “a search for a place to feed or breed that should stop when the resources being sought are encountered” – and directed. Either way, “these flights occurred over distances up to 1,200km across the arid inland.”. Thus, Grey Teal disperse widely throughout the Australian continent due to adaption to environmental change such as flooding, extensive dry periods or lack of food . This process is carried out to seek their preferred environment of shallow wetlands with sufficient food supply and suitable breeding conditions. However, it is uncertain as to whether this behaviour should be referred to as 'migration' or whether a more appropriate term would be 'ranging' . The same applies in New Zealand where the species is very mobile. This flying skill implies that the local population of Grey teal changes constantly, both in New Zealand and Australia, which can lead to quick changes in numbers at any locality. Moulting Adult Grey teal, Anas gracilis, undergoes a flightless moult that is not fixed in the year. Before breeding season mature birds, both male and female, will undergo a body moult that excludes the wings . Then after breeding season, both partners will undergo a complete body moult (including wings). According to Janet Kear (2005), in Australia the moult of this species is correlated with climate conditions. Indeed during prolonged wet season birds postpone wing moult in order to extend the breeding one – probably in order to better exploit wetlands resources. This postponement could be explained by the fact that ducks try not to moult and breed at the same time. For some species of birds it is even impossible to do both simultaneously . If we have to draw a tendency we could say that body moult (including wings) generally occurs between the months of January to March when it is late summer or early winter . Juveniles will undergo a complete moult of the entire body other than the wings, occurring in the first autumn or early winter . Brooding Female Grey Teals will brood young by themselves, however, when necessary (e.g. death of 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 . Juveniles 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 . Survival rates and life expectancy From a study completed J.A.Mills on the morality and Status of Grey Teal in New Zealand, approximate survival rates were established. To establish the rate of survival, the birds were banded. It was recorded that 68% of juveniles die within the first year of life, 77% by their first two years of life and then 85% by the end of their fourth year . Thus resulting in approximately 0.96 years of expected life for juveniles after they have been banded (age of 2-4 months). For Grey Teal that survive to one year of age, they are expected to have a further 2.9 years of life. For adults, the mean average was 50% of deaths annually, whereas for juveniles it was 68% . Similar results were shown in an Australian study where the mean average of deaths for adults was 52%, and for Juveniles 66% . Therefore from the data collected, it can be assumed that Grey Teal has an approximate life expectancy of between 2-4 years old. However, some exceptions occurred since the oldest adult recorded in the wild in New Zealand was 9 years old. It was 21 years old in Australia .

Grey Teal mainly consumes invertebrates such as larvae and small crustaceans, complemented by aquatic plant seeds. With a varied diet shifting seasonally, grey Teal forages by dabbling and upending in shallow waters, and dredging in mudflats. They forage independently, forming flocks post-breeding, and feed during the day and night.

Grey Teal is commonly found in various wetland habitats, including lagoons, swamps, shallow lakes, and temporary flooded areas, favoring freshwater environments but also occupying brackish and saline waters. These habitats typically feature ample marginal vegetation, which is essential for concealing nests among ground-level reeds and tall grasses or within elevated tree hollows. Grey Teal usually resides in elevations below 300 meters and is highly adaptable, frequenting sewage treatment plants and coastal lagoons. In some regions, grey Teal also utilizes agricultural landscapes, such as rice fields, as part of its habitat range.