Guillemot Life Cycle: Nest Building To Fledging (and everything in between)
Guillemots are seabirds that typically only come ashore to breed during the summer months. Most will spend the winter out at sea but there are a few that remain in inshore waters all year round.
Guillemots are marginally larger than Razorbills and have a brown head and upper body with a white lower body. If spotted from a distance, the brown colouration can appear black. They have a long slender black bill, a short tail and a distinct dark line behind their eyes.
Guillemots are generally only found on coastal cliffs with large colonies nesting in the north of England and Scotland. To find out more about these fascinating members of the Auk family, keep reading.
Table of Contents
How Long Does A Guillemot Live?
The average lifespan for a Guillemot is around 23 years in the wild. However an individual was found recently that had survived for an astounding 40 years and 11 months according to ring records.
They typically reach sexual maturity and start to breed at around the age of 5.
How Fast Can A Guillemot Fly?
Although they are adept swimmers and dive underwater in search of food, Guillemots can reach speeds of up to 50 mph (80 km/h) when flying.
They are often spotted flying fast and low over the sea and can reach their top speeds when flying in a straight line. However, they are not the most agile birds when trying to manoeuvre in the air or when coming in to land on the narrow cliff edges where they nest.
Are Guillemots Aggressive?
In general, Guillemots are not considered to be aggressive birds. They tend to be peaceful and often ignore other birds and animals. However, that all changes during the breeding season.
Guillemots tend to nest in large colonies and inhabit relatively small areas for their nests. This leads to incredibly fierce territorial disputes with their neighbours.
They will lunge at intruders with their bill open, jab at them with their bills and chase them on land and at sea. Even the chicks will jab at intruders with their bills.
These territorial disputes often end in actual physical fights which involve lots of bill jabbing and wing clashes.
What Is A Guillemot’s Habitat?
Guillemots spend most of their time at sea except during the breeding season when they can be found on rocky cliffs using narrow ledges as nesting sites. They tend to nest in large colonies and can be spotted around much of the UK’s coastline in places like rocky outcrops on islands, cliffs and sea stacks.
How Long Does It Take For A Guillemot To Build A Nest?
Guillemots don’t build nests in the traditional way and simply lay their eggs on rock ledges on cliffs. They rely on natural features and the pyramidal shape of their eggs to prevent them from rolling off their narrow ledge.
As Guillemots don’t build nests, it takes next to no time to establish a nesting site. However, because they breed in such large colonies, they spend a considerable amount of time defending their particular part of the ledge from intruders.
A typical breeding territory of a Guillemot is only slightly larger than the bird itself.
Eggs
Once the pair have established a small piece of cliff ledge, the female will lay her egg. This is an important stage in the life cycle of the Guillemot as it introduces the next generation.
When Do Guillemots Lay Eggs?
Egg laying can occur any time between mid April and late May but typically takes place around early May. The exact timing of egg laying can be influenced by a number of factors including the weather, the temperature and the age and health of the female.
How Many Eggs Does A Guillemot Lay?
Guillemots generally only lay one egg, however, some species can lay two eggs. Typically, they only have a small area to nest in which can also influence the number of eggs laid.
There’s simply not enough physical space to lay more than one egg in many cases.
What Do Guillemot Eggs Look Like?
The main identifying feature of a Guillemot’s egg is its shape. They are narrow and pointed at one end with a larger, rounded end at the other side. This shape is often described as pyriform, pyramidal or pear-shaped.
The egg itself can be white, pale blue, dark blue or green. Many have dark spots, speckles, blotches or squiggles. Each egg has distinct and unique marking and colour which make it easy for the parents to identify their own egg.
The eggs are fairly large at around 82 x 50 mm and weigh around 108 grams. 11% of that weight is the shell which is important to prevent it cracking too soon on the hard cliff ledge.
How Long Do Guillemot Eggs Take To Hatch?
Both parents take turns incubating their egg non-stop for around 28 to 32 days. The chicks take 3 to 4 days to completely hatch and are covered in black downy feathers.
Chicks
Once the egg hatches, we move on to the next stage of the life cycle of the Guillemot, the chick.
How Many Chicks Does A Guillemot Have?
Guillemots tend to only have one chick which corresponds to the number of eggs laid. They only have one brood per year but often return to the same nesting site year after year.
When Do Guillemot Chicks Open Their Eyes?
Guillemot chicks hatch with their eyes already open. These chicks are known as precocial, meaning they are relatively well developed at birth, with open eyes and covered in down. This allows them to be more active and mobile soon after hatching, though they still rely on their parents for warmth and feeding.
In the early days after hatching, the chicks remain on the cliff ledges with their parents before they eventually make a dramatic leap into the sea when they are around 3 weeks old. At this time, the chicks cannot fly, they simply parachute down from the cliff face into the water below.
Sometimes they hit the rocks at the water’s edge but they have such dense downy feathers that they can survive even quite drastic falls.
When Do Guillemot Chicks Fledge?
When the chicks throw themselves off the cliff and into the water at around 3 weeks old, they don’t have the ability to fly or care for themselves. The male takes care of the young chick teaching it how to dive in search of food and generally looking after the youngling.
It’s not until around 5 or 6 weeks after hatching (around 2 to 3 weeks after first hitting the water) that the younglings take their first flight (or fledge).
SEE ALSO: Barn Owl vs Tawny Owl: Key Differences Explained
Frequently Asked Questions
The average lifespan of a Guillemot is around 23 years in the wild. However an individual was found recently that had survived for an astounding 40 years and 11 months according to ring records.
Guillemot eggs can be found in various colours ranging from white, pale blue, dark blue or green. They may or may not be covered in dark spots, speckles, blotches or squiggles. These unique markings and colours allow the parents to identify their own egg in the tightly packed breeding colony.
No, despite the similarities in appearance, Guillemots are not Penguins. They belong to different bird families even though the original name for the Guillemot was “Penguin” which is a Welsh word meaning “white head”.
