The great grey owl is the largest owl species in North America and one of the largest owl species in the world. Given their impressive size, great grey owls have hearty appetites to satisfy. But just how much does a great grey owl eat? Let’s take a closer look at the diet and feeding habits of these majestic birds.
What Do Great Grey Owls Eat?
Great grey owls are opportunistic predators, meaning they will eat a variety of prey depending on what is available in their habitat. Their main prey items include:
- Small rodents like voles, mice, rats, squirrels, and pocket gophers
- Small birds like juncos, sparrows, and grouse
- Insects
- Amphibians like frogs and salamanders
- Reptiles like snakes and lizards
- Fish
Rodents such as voles and mice make up the bulk of a great grey owl’s diet, accounting for 50-90% of their food intake. These nocturnal raptors use their incredible hearing to locate small mammals scurrying under the vegetation or snow. They will also snatch up diurnal rodents like ground squirrels and pocket gophers.
Birds are the second most common prey item for great grey owls. They capture avian prey in flight or pluck them from nests and perches. Great grey owls inhabiting coastal regions will also prey on fish and marine invertebrates like crabs.
How Much Does a Great Grey Owl Eat Per Day?
Great grey owls have hearty appetites that require lots of prey. On average, an adult great grey owl will consume around 3-5 mice or voles per day, or approximately 50-150 grams of food per day.
However, their food intake can vary considerably depending on factors like:
- Age – Nestlings and fledglings eat considerably more than adult owls relative to their body size as they need extra nutrition for growth and development.
- Season – More food is required in winter months when prey is scarce.
- Breeding season – Great grey owls ramp up their hunting efforts during breeding season to feed their mates and offspring.
- Prey availability – Food intake will increase or decrease depending on prey numbers.
- Climate conditions – Colder climates require more calories for thermoregulation.
Great grey owls are also capable of gorging themselves when prey is abundant. They have been known to consume up to 9 rodents in a single hunting outing.
How Often Does a Great Grey Owl Eat?
Great grey owls typically hunt at night or during crepuscular hours around dawn and dusk. They will hunt for several hours at a time, consuming multiple prey in one sitting. Great grey owls are not frequent feeders like many smaller bird species. They can survive on one moderate-sized meal every couple of days when prey is scarce.
In the peak of breeding season when food demands are highest, great grey owls may hunt during daylight hours as well as nighttime. Nursing female great grey owls and rapidly growing nestlings require the most frequent feedings to support their high energy requirements.
How Much Does a Great Grey Owl Eat Annually?
It’s estimated that a wild great grey owl consumes between 2,000 – 5,000 grams of prey annually. This equals around 2,000-5,000 individual rodents each year. However, annual food intake can vary substantially based on the factors mentioned earlier.
In one research study, scientists examined the regurgitated pellets from a family of great grey owls throughout the breeding season. Here’s how much prey they consumed:
- Male great grey owl: 1,600 grams over 3 months
- Female great grey owl: 3,710 grams over 3 months
- 3 nestlings: Approximately 4,500 grams total over 2 months before fledging
This gives you an idea of the quantity of prey these raptors can consume, especially when feeding demanding nestlings.
How Does a Great Grey Owl Hunt and Eat Its Prey?
Great grey owls have a number of specialized adaptations that make them effective hunters:
- Excellent hearing – Their dish-like facial disc channels sound to their ears, allowing them to pinpoint even faint noises from small mammals moving under grass or snow.
- Tunable facial disc – They can adjust their facial disc to hone in on certain frequencies, filtering out ambient noise.
- Lightweight body – Long wings and dense, soft plumage allow them to fly silently.
- Sharp talons – Needle-like talons deliver a deadly grip to seize prey.
- Powerful beak – Their large hooked beak easily tears prey into pieces.
Here is the great grey owl’s typical hunting process:
- Perch and wait silently for prey sounds.
- Pinpoint prey location by sound alone.
- Fly or glide stealthily towards prey.
- Use sharp talons to snatch prey.
- Deliver a killing bite with the beak.
- Consume prey whole or tear into smaller pieces.
- Regurgitate indigestible fur, bones, and teeth as pellets.
Great grey owls employ a “sit and wait” hunting strategy. Their incredible hearing allows them to remain perched motionless until prey is detected. They then use surprise aerial attacks or short bursts of speed on foot to capture prey.
Do Great Grey Owls Store Food?
Most owls swallow their prey whole and digest everything but the fur and bones. Unlike some raptors, great grey owls do not have crops to store undigested food for later. They also do not gather caches of prey like some mammals.
However, great grey owl parents have been observed stashing extra prey on tree branches or wedged in nooks near their nest. This allows them to ensure a steady food supply for their hungry brood of nestlings. The male owl does most of the hunting and food delivery to the nest during breeding season.
What Happens If a Great Grey Owl Misses a Meal?
In the wild, great grey owls do not always catch prey at every hunting attempt. Because they have slow metabolisms and can go days between feedings, missing one or two meals does not cause great hardship. However, missing too many meals can deplete their energy reserves and cause severe hunger.
During periods of prey scarcity like a vole population crash, great grey owls may enter an energy conservation mode. They will reduce activity and become more energy efficient to get by on fewer calories. However, extended food shortages can eventually cause starvation and higher mortality rates, especially among vulnerable juveniles.
Do Great Grey Owls Drink Water?
Great grey owls get most of the moisture they need from their prey. Small mammals like rodents contain a lot of water in their bodies. The owls also derive some water from moisture on plants when foraging at night.
Great grey owls will drink from water sources like rivers, lakes, and puddles on occasion, especially on hot summer days. However, they do not need to drink water daily or routinely like some animal species. The absence of drinking water does not significantly affect their hydration status or survival.
How Does the Great Grey Owl’s Diet and Appetite Compare to Other Owls?
As a large owl species, the great grey owl unsurprisingly eats much more than smaller owl varieties. Here’s how its daily and annual dietary intake compares with other owls:
| Owl Species | Average Weight | Daily Food Intake | Annual Food Intake |
|---|---|---|---|
| Great Grey Owl | 1.4-2.7 lbs | 3-5 mice or 50-150 g | 2,000-5,000 g |
| Great Horned Owl | 3-5 lbs | 250-350 g | 5,000-10,000 g |
| Snowy Owl | 3.5-6.5 lbs | 150-250 g | 3,000-7,500 g |
| Eastern Screech Owl | 0.15-0.3 lbs | 10-30 g | 500-1,500 g |
| Elf Owl | 1.4-2.75 oz | 5-10 g | 200-700 g |
The great grey owl’s large size allows it to take a wider range of prey and consume more food than pint-sized owls like the elf owl. However, giants like the great horned owl exceed the great grey in sheer bulk and predatory capacity.
Key Takeaways on Great Grey Owl Diet and Feeding
Here are the key points on great grey owl dietary habits and appetites:
- Prey mostly on small mammals like voles, mice, and pocket gophers.
- May eat 2,000-5,000 grams of food per year.
- Require 3-5 mice or 50-150 grams daily.
- Can go days between feedings.
- Hunt mostly at night or at dawn/dusk.
- Don’t store food but may cache extra food near nest.
- Can survive short fasts by lowering activity and metabolism.
- Rrival larger owl species like great horned owls in food intake.
Conclusion
The great grey owl is a consummate hunter that can detect faint prey sounds from great distances. These large raptors are capable of consuming impressive quantities of rodents, birds, and other prey to support their substantial size and high energy needs. While prey availability drives some fluctuations in their diet, great grey owls are well-adapted to find and catch enough sustenance to thrive across their range.
