Greylag geese (Anser anser) are a common species of goose found throughout Europe, North Africa, and Asia. As their name suggests, they have gray feathers and long legs. Greylag geese are grazing birds that live near marshes, lakes, pastures, and meadows. They are an important game bird and have long been domesticated. A key question about greylag geese is how many eggs they lay.
Typical Clutch Size
The typical clutch size for greylag geese is 5-6 eggs. The female lays one egg per day, so it takes 5-6 days for her to complete laying a full clutch. The eggs are oval-shaped with a smooth, glossy shell. They are quite large, averaging about 3.9 x 2.8 inches (10 x 7 cm) and weighing 5.8-8.5 oz (165-240 g). The color of greylag eggs can vary from creamy white to pale green.
Greylag geese only have one clutch per year. They breed in the spring, typically starting in late March or April in most parts of their range. The female builds the nest out of plant material such as reeds, rushes, grass, moss, and sticks. Good nesting sites are on small islands in lakes or marshes, in long grass near water, or in other secluded spots. The nest is bowl-shaped with a lining of down feathers plucked from the female’s breast to help insulate the eggs.
Once the full clutch of 5-6 eggs has been laid, the female starts incubating them. She sits very tightly on the nest and is reluctant to leave it. The male stands guard nearby and will aggressively chase away potential predators. Both parents are highly protective of their nest and eggs.
Egg Development
Greylag goose eggs take around 28-30 days to hatch. The goslings hatch in the order the eggs were laid, usually over a 12 to 24 hour period. Within a day after hatching, the female leads the goslings from the nest to water where they learn to find food like small aquatic plants, seeds, and insects.
The goslings grow rapidly on this high protein diet and are able to fly at 6-7 weeks old. They remain with their parents through their first winter. By spring when the adults are ready to breed again, the young geese have to find their own territory and mate.
Nest Site Selection
Nest site selection is important for successful breeding in greylag geese. They prefer to nest in places with low risk of predation and human disturbance. Islands on lakes or marshes offer ideal protection. The water acts as a moat, limiting access to terrestrial predators like foxes.
Greylags also seem to preferentially choose nest sites with specific vegetation features. Having tall, dense vegetation around the nest helps screen it from view. Common nesting plants include reeds (Phragmites), bulrushes (Scirpus), cattails (Typha), sedges (Carex), nettles (Urtica), and rushes (Juncus).
Additionally, greylags favor nest sites close to feeding areas with tender, nutritious grass shoots. This allows the female easy access to food during incubation recesses when she briefly leaves the nest to eat and drink.
Clutch Size Variation
While 5-6 eggs is typical, clutch size in greylag geese can vary between 3-12 eggs. Some factors that influence clutch size include:
- Age of female – Younger, less experienced females lay smaller clutches.
- Nutrition – Females in better physical condition with access to quality food lay larger clutches.
- Weather – Harsher weather and shorter growing seasons may limit clutch size.
- Predation – Higher risk of nest predation favors smaller clutches.
- Location – Population density, habitat quality, and other local conditions impact clutch size.
In North America, introduced greylag geese populations tend to have smaller average clutch sizes of 3-5 eggs compared to native European flocks. This may reflect differences in nutrition, predation risk, and other factors between the two continents.
Large Clutches
Greylag geese are physiologically capable of laying very large clutches. In exceptional cases, they may lay up to 12-14 eggs. However, clutches over 8 eggs are rare. Extremely large clutches are not evolutionarily advantageous because the parents struggle to successfully incubate so many eggs and raise such a big brood.
Small Clutches
At the other extreme, greylag clutches containing just 1-3 eggs are uncommon but can occur. Small clutches happen when the female is young, in poor health, or lacking adequate nutrition and fat reserves for egg production. Predation and egg damage can also limit clutch size if the female has to continually replace lost eggs.
Incubation Period
The incubation period for greylag goose eggs averages 28-30 days but can vary from 25-32 days depending on temperature conditions. Eggs kept at the high end of the goose’s incubation temperature range around 99-102°F (37-39°C) will hatch faster compared to cooler eggs.
Incubation starts after the last egg is laid. The female is very committed to nest sitting and may lose 15-20% of her body weight during incubation as she eats and drinks very little. The male stands guard nearby to protect the nest from threats.
Greylag geese have one of the longest incubation periods among waterfowl. Related species like Canada geese and barnacle geese have an incubation time of 24-28 days. The longer incubation period of greylags may be an adaptation to their temperate European climate with colder spring weather. The extra time in the egg allows goslings to develop more feathers and fat stores before hatching.
Nesting Success Rate
The nesting success rate for greylag geese can vary greatly between different regions and habitats. Overall, greylags have relatively good nesting success compared to other goose species.
In natural wetland areas with low human disturbance, nesting success may exceed 80%. However, rates are lower in suboptimal or riskier nesting locations. One Swedish study found an average nest success rate of 74% for island nests compared to just 47% on mainland coasts with more predators and human activity.
Greylag nests are most vulnerable to mammals like foxes, mink, raccoon dogs, and wild boar which can destroy eggs or kill the brooding goose. Gulls may also take eggs opportunistically. Farming activities in agricultural areas may impact 10-15% of nests.
Climate factors like severe storms, flooding, or freezing temperatures can also lower productivity by destroying nests. Overall, a good benchmark for greylag goose nest success is 60-70% in most habitats.
Egg Hatchability
Egg hatchability refers to the percentage of fertilized eggs that successfully hatch. For greylag geese, reported hatchability rates are generally 80-90%. This indicates the majority of embryos develop normally given proper incubation.
However, egg fertility and hatchability can vary based on the health and age of the breeding adults. Younger, inexperienced breeders tend to have lower fertility and hatch rates. Environmental toxins in polluted wetlands may also harm embryo development.
One study of reintroduced greylags in England found noticeably lower fertility and hatchability compared to wild greylags on the European continent. This was attributed to the small founder size and limited genetic diversity of the reintroduced English population.
In optimal conditions with healthy adult geese, fertility should reach 90-95% with almost all fertilized eggs hatching successfully. Careful incubation by the dutiful parents ensures good hatchability.
Gosling Survival Rate
High egg hatchability in greylags is balanced by substantial mortality of goslings in the first few weeks after hatching. Average gosling survival rates during this period range from 40-60%.
Newly hatched greylags are quite vulnerable to predators, exposure, and accidents. Younger, inexperienced parents may not adequately care for and protect their young. Foxes, mink, gulls, ravens, and other predators take a heavy toll on goslings.
Harsh spring weather with cold temperatures, rain, and wind can be deadly for small goslings with poor thermoregulation. Trampling by cattle or wild ungulates may kill some goslings in pastures used for grazing.
If the parents lead them across roads near nesting areas, fast-moving vehicles can strike goslings. Polluted water sources with toxic algae or oil spills also pose hazards. With all these dangers, first-year mortality of 40-60% is typical in most greylag populations.
Adult Mortality Rate
Greylag geese are a relatively long-lived species, giving them multiple opportunities to breed over their lifetimes. Annual adult mortality rates average 10-15% once the geese reach sexual maturity after their second year.
The oldest known greylag goose was reportedly 41 years old after being banded and studied by researchers in Sweden for decades. Captive greylags may live over 30 years in zoos or private waterfowl collections.
Natural causes of greylag goose mortality include predation, disease outbreaks, extreme weather events, and complications like impacted crops or angel wing deformity. Collisions with power lines, wind turbines, or vehicles account for some additional deaths, especially among migratory populations.
Legal hunting harvests greylags in many areas, taking a toll on local adult numbers. Some illegal poaching likely occurs also. But overall, greylags have an excellent annual survival rate compared to many other waterfowl species.
Population Size and Trends
The total global population of greylag geese is estimated at around 2.6-5.4 million individuals. About 88% of the population resides in Europe, with the remainder in North Africa and Asia.
Region | Estimated Population |
---|---|
Northwest Europe | 2,200,000 |
Central Europe | 1,200,000 |
Black Sea | 500,000-1,500,000 |
Southwest Asia | 150,000-500,000 |
North Africa | 250,000 |
Greylag numbers declined historically due to wetland loss but rebounded strongly in the 20th century. Conservation measures and reduced hunting pressure helped populations recover. Some flocks have grown so abundant they are now managed as agricultural pests.
Reintroduction programs have established greylags in areas like Britain, where the native population was extirpated. Escaped domestic greylags have also naturalized in new regions. While some populations migrate, others are increasingly shifting to year-round residence near food sources.
With their adaptable and opportunistic nature, greylag geese remain a thriving species across Eurasia and Africa. Their vocal nature and familiarity around humans will likely ensure greylags remain a prominent waterfowl species for the foreseeable future.
Conclusion
In summary, greylag geese typically lay clutches of 5-6 eggs, with variations from 3-12 eggs possible depending on the individual female’s condition and habitat. The eggs hatch after an incubation period averaging 28-30 days if properly incubated by the parents. While hatchability is high, gosling mortality can also be quite substantial in the first few weeks after hatching. But adult greylags have a long lifespan and good annual survival. Their populations are flourishing across much of their native range.