Storm Petrel Diet and Size: Feeding Habits, Predators, and Measurements
Storm petrels have an extraordinary ability to smell, which is quite rare among birds. This trait enables them to find food sources with astonishing accuracy, even across the expansive ocean.
Their distinct scent, often noted as musky, is not only captivating but plays a significant role in their social activities, such as mate selection and recognising their nests, as it is frequently used for marking territory and identifying members of their species.
Curious about their diet and breeding? Keep reading to learn how Storm Petrels thrive in their oceanic environment.
Table of Contents
The Dietary Habits Of The Storm Petrel
Let’s take a look at what a Storm Petrel eats and how they feed their young.
What Does A Storm Petrel Eat?
The diet of Storm Petrels consists mainly of small fish, crustaceans, jellyfish, and squid. They are expert at gliding over the ocean’s surface for these prey, frequently seen pattering on the water with their wings in a V formation to capture food. They often follow boats and fishing vessels to find food and may gather near fish farms.
These seabirds display unique techniques for feeding, such as hovering over the water or taking short dives to pick up small morsels. Storm petrels also take advantage of diving predators like penguins and seals that bring prey to the surface, aiding their feeding efforts.
What To Feed A Baby Storm Petrel?
Adult Storm Petrels usually provide their chicks with a regurgitated oily substance. This oil, which is high in nutrients and energy, is produced in the adults’ stomachs from partially digested prey such as small fish and crustaceans. The regurgitated oil aids the chicks in rapidly growing and maintaining their energy levels in the early stages of their growth.
The oily substance is a crucial part of the diet for baby storm petrels, optimising the energy they receive at each feed, which is important as the parents usually feed the chicks only once per night. This high-energy diet is key for the chicks to develop the strength needed to fledge.
Breeding Habits Of Storm Petrels
Exhibiting breeding habits adapted to their oceanic life, Storm Petrels typically nest on isolated rocky headlands and uninhabited islands off the Atlantic and Mediterranean coasts of Europe, choosing sites without land predators like rats and cats.
These nests are commonly found in natural crevices, burrows, or beneath rocks to guard their eggs and chicks. The breeding season typically starts in late April and can stretch into July. At this time, the birds are nocturnal at their breeding sites to avoid predators and are also active at night when feeding near the coast.
When the breeding season ends, storm petrels migrate to their wintering areas off the coastlines of South Africa and Namibia. The juveniles often don’t return to the breeding grounds until they are two or three years old.
Do Storm Petrels Mate For Life?
Yes, Storm Petrels are known to mate for life. They create long-term monogamous partnerships and tend to use the same nesting place each year.
This is typical among several seabird species, including storm petrels. Their strong pair bonds ensure successful breeding, care for their offspring, and stability in their colonies. Both parents share duties of egg incubation and feeding the chick with oily regurgitated stomach contents.
The Size & Weight Of Storm Petrels
Let’s take a look at the size and weight of storm petrels, including how much they weigh and their overall dimensions.
How Much Does A Storm Petrel Weigh?
Weighing in at 23 to 30 grams, with an average of 28 grams, European storm petrels are slightly bigger than robins. These seabirds are known for their black feathers, white rump, and distinctive white bands on their underwings.
How Big Is A Storm Petrel?
European storm petrels are fairly small seabirds. They measure between 14 and 18 centimetres (5.5 to 7.1 inches) in length, and their wingspan is 36 to 39 centimetres (14.2 to 15.4 inches). Their small stature and distinctive all-black plumage with a white rump make them easy to identify, particularly in flight over the sea.
Are Storm Petrels Under Threat?
The Storm Petrels are under threat from various dangers with predation by invasive species like rats and cats being a key issue. These predators consume their eggs and chicks, which is especially troubling on islands where they have been introduced, resulting in significant reductions in petrel numbers.
Another threat is climate change, which brings about changes in their habitat and food supply. Rising sea temperatures and changing weather conditions could disrupt the foraging grounds and breeding locations of these seabirds.
Despite certain threats, storm petrels are still deemed “Least Concern” by the IUCN due to their large and widespread population. Under the UK conservation status, Storm Petrels are classified as “Amber” indicating that they are of moderate conservation concern. However, some localised declines and possible future dangers mean that conservation work must continue to keep an eye on and protect their breeding areas.
What Eats A Storm Petrel?
In their natural ocean habitats, adult Storm Petrels face predation from various bird species. Peregrine Falcons, along with other seabirds like Great Skuas, Great Black-backed and Yellow-legged Gulls, frequently hunt these birds, especially focusing on fledglings and adults during the night.
Additionally, Eleonora’s Falcons and owls, such as Barn Owls, are also expert predators that can greatly affect local petrel numbers by hunting both adults and chicks.
The eggs and chicks of Storm Petrels on land are vulnerable to invasive species such as rats and cats, which can greatly diminish breeding colonies by preying on the young and eggs. These threats are particularly severe on islands where these mammals have been brought in.
Where Can I See Storm Petrels In The UK?
Throughout the UK, Storm Petrels can be observed in several locations, especially during the breeding season and migration. A key spot to witness these birds is Mousa, a small, uninhabited island off Shetland, where visitors can take a ferry to see their nocturnal breeding routines.
In Scotland, you can find these birds breeding on the west coast, the Western Isles, Orkney, and Shetland. They nest in burrows, rocky crevices, and dry stone walls, often choosing islands free from invasive species such as rats.
Across the British Isles, storm petrels also breed on secluded islands off the western shores of England, Wales, and Ireland. These birds are seldom seen as they live mainly at sea, only coming to land to breed on remote islands.
SEE ALSO: Storm Petrel Life Cycle: Nest Building To Fledging (and everything in between)
Frequently Asked Questions
Storm Petrels are fairly small seabirds, measuring between 14 and 18 centimetres (5.5 to 7.1 inches) in length, with a wingspan of 36 to 39 centimetres (14.2 to 15.4 inches). They weigh between 23 and 30 grams, averaging around 28 grams.
A Storm Petrel eats small fish, crustaceans, jellyfish, and squid. They often follow boats and fishing vessels, gliding over the ocean’s surface to capture their prey. They also take advantage of diving predators like penguins and seals that bring prey to the surface.
The predators of the Storm Petrels include birds such as Peregrine Falcons, Great Skuas, Great Black-backed Gulls, Yellow-legged Gulls, Eleonora’s Falcons, and Barn Owls. On land, their eggs and chicks are vulnerable to invasive species like rats and cats.
Some interesting facts about Storm Petrels are their extraordinary ability to smell, which helps them find food with precision across the ocean. Their musky scent plays a significant role in social activities like mate selection and nest recognition. Storm Petrels also mate for life, forming long-term monogamous partnerships and often using the same nesting place each year.
