Cormorants are medium-to-large sized seabirds that live along coastlines and build nests near cliffs or on the ground. There are around 40 different species of cormorants found throughout the world, with varying lifespans depending on the specific species.
Quick answer
On average, most cormorant species live approximately 10-15 years in the wild. Some species may live up to 20 years, while the oldest known cormorant in captivity lived to 34 years old.
Average lifespan by species
Here is a breakdown of the average lifespan of some common cormorant species:
Species | Average Lifespan |
---|---|
Double-crested Cormorant | 10-15 years |
Great Cormorant | 12-15 years |
Japanese Cormorant | 12-20 years |
Pelagic Cormorant | 12-18 years |
As seen in the table, most cormorant species typically live 10-15 years on average in their natural environment. The Japanese cormorant is one of the longer lived species, with lifespans reaching up to 20 years.
Factors affecting cormorant lifespan
There are several factors that can influence how long cormorants live:
Predation
Cormorants can fall prey to larger predators like eagles, foxes, coyotes, and raccoons. Predation, especially on younger cormorants, can reduce average lifespan.
Starvation
Starvation due to lack of food resources, especially in winter, can be a threat to cormorant survival and longevity.
Disease
Bacterial, viral, or fungal infections can spread rapidly in cormorant colonies. Diseases like avian cholera can shorten lifespan.
Environmental threats
Oil spills, pesticide pollution, habitat loss, and severe weather events may all negatively impact cormorant health and longevity.
Fishing tackle entanglement
Cormorants can become entangled in fishing line, lures, hooks, and nets, which can cause lethal injuries or lead to death by drowning.
Why do cormorants have relatively long lifespans for birds?
There are a few key reasons why cormorants tend to live longer than many other birds:
Low metabolism
Cormorants have relatively low metabolic rates compared to similar-sized birds, which conserves energy and can extend lifespan.
Few natural predators
Since cormorants nest on cliffs or isolated islands, they have fewer interactions with land-based predators, increasing survival odds.
Divable physiology
Cormorants’ robust body structure and special feathers allow them to dive deep underwater to catch fish while avoiding aquatic predators.
Small clutch sizes
Cormorants lay only 2-5 eggs per clutch. With fewer offspring to provide for, adult cormorants can focus on self-preservation.
Oldest known cormorant
The oldest known cormorant was a Great Cormorant that lived in captivity at the Philadelphia Zoo. This cormorant lived to the incredible age of 34 years old, more than double the average lifespan for wild cormorants.
In their natural habitat, cormorants are thought to very rarely surpass 20 years of age. Their relatively long lifespans compared to other similar seabirds reflects their adaptions for finding fish even in challenging conditions.
Cormorant lifespan compared to other birds
Compared to other birds, cormorants generally have moderately long lifespans. Here’s how cormorant longevity compares:
Shorter than large bird species
Large bird species like albatrosses (50 years), swans (24 years), and eagles (28 years) often outlive cormorants.
Longer than small songbirds
Small passerine songbirds like finches (2-6 years) and larks (3-7 years) have much shorter lifespans than most cormorants.
On par with seabirds
Cormorants have similar lifespans to other seabirds like gulls (15 years), pelicans (15 years), and skuas (12 years).
Shorter than parrots
Parrots are exceptionally long-lived for their size and can live 60-80 years, far surpassing cormorants.
Lifespan in captivity
In zoos, aquariums, and other captive settings, cormorants generally live significantly longer than in the wild, with lifespans upwards of 25-30 years and sometimes longer.
Reasons cormorants often have longer lifespans in captivity include:
- Greater protection from predators
- Reliable access to food and water
- Close monitoring and veterinary care
- Lower stress environment
However, captive lifespans are still quite short compared to parrots and corvids (crows, ravens) which may live up to 60-80 years in captivity.
Effects of longevity on population
The moderately long lifespans of cormorants, coupled with a relatively small clutch size, means that adult survival is important for maintaining stable cormorant populations. Population growth is slow since they raise fewer young per year compared to short-lived songbirds.
Loss of adult cormorants in events like oil spills can have long-lasting impacts on local populations. Cormorants rely on the knowledge and experience of older individuals to improve breeding and foraging success.
On the other hand, the limited longevity and reproduction of cormorants prevents populations from irrupting out of control. Mortality and slower replacement keeps populations in check compared to some other seabird species.
Age-related changes
As cormorants grow older, they experience some changes that may affect their health and survival:
Plumage color loss
Breeding adults lose some of the vivid colors and white patches seen on younger cormorants as they age.
Beak / eye ring color changes
Some cormorant species develop paler beaks and eye rings when older.
Declining waterproofing
The waterproofing effectiveness of feathers may decrease with age.
Vision deterioration
Vision worsens over time, possibly impacting hunting ability.
Arthritis
Joint inflammation from arthritis may become more common in older cormorants.
Lower fecundity
Older cormorants tend to produce fewer eggs and offspring than younger individuals.
Estimating cormorant age
It can be challenging to estimate the exact age of wild cormorants, but here are a few techniques used:
Leg bands
Tracking banded cormorants over time provides accurate age data.
Plumage and soft part colors
Comparing changes in plumage patterns, beak coloration, and eye ring color to known patterns can provide a rough estimate of age.
Courtship behaviors
Younger cormorants engage in more elaborate courtship displays than older, mated birds.
Brood patch scar tissue
The amount of scar tissue on brood patches (breast feathers) indicates approximate age.
Increasing cormorant longevity
Some measures that could help increase cormorant lifespans include:
- Reducing pollution that can poison food sources
- Preventing disturbance of nesting sites
- Maintaining suitable habitat
- Mitigating climate change impacts
- Developing safer fishing tackle technology
- Cutting plastic pollution and marine debris
With proactive conservation programs, improved population monitoring, and reducing man-made threats, cormorant lifespans could potentially be extended closer to their biological maximum.
Conclusion
Most cormorant species typically live 10-15 years on average in the wild, with lifespans reaching up to 20 years in some cases. The oldest known cormorant was 34 years old. Compared to other birds, cormorants have moderate longevity due to their adaptations for finding fish and avoiding predators. Supporting cormorant conservation efforts could help increase average lifespans, which would benefit population stability.