The red squirrel is a small, diurnal rodent integrated into its forest ecosystem, primarily inhabiting coniferous and mixed woodlands. Its agility and arboreal lifestyle define its place in the food web. As a scatter-hoarder of seeds, nuts, and fungi, the red squirrel plays a role in forest regeneration. However, its small size and reliance on the forest canopy make it a frequent target for a diverse array of predators, establishing it as a primary prey species.
Arboreal and Aerial Hunters
The greatest threat comes from predators that match the squirrel’s agility high in the trees or strike from the air. The Pine Marten stands out as a specialized mammalian predator, capable of pursuing squirrels directly through the forest canopy. This slender mustelid is equally at home in the treetops, making it a difficult foe to escape. Squirrels that have co-evolved with the Pine Marten have developed stronger anti-predator responses, reducing their vulnerability.
In the air, specialized raptors are a constant danger. The Northern Goshawk is one of the most significant avian hunters, often taking squirrels in the dense forest. Squirrels are a regular part of the Goshawk’s diet, especially during winter when other prey is scarce and the squirrel is more visible. Smaller hunters like the Northern Pygmy Owl are also known to prey on red squirrels. Owls, including the Tawny Owl and Ural Owl, occasionally include squirrels in their diet.
Terrestrial and Opportunistic Predators
While the red squirrel spends most of its time high off the ground, it is still vulnerable to predators that hunt on the forest floor or are opportunistic. Mammals like the Red Fox, Coyote, and bobcats prey on the red squirrel when it descends to forage or access its cached food stores, known as middens. The squirrel is most at risk from these ground-dwelling carnivores when forced to cross open ground or when focused on gathering resources.
The opportunistic nature of these terrestrial hunters also extends to raiding the squirrel’s home or young. Domestic and feral cats are common predators that catch squirrels when distracted or close to the ground in fragmented habitats. Weasels and stoats, though small, can enter the squirrel’s drey (nest) to prey on nestlings. Furthermore, some larger snake species pose a threat by climbing trees to raid nests, targeting the young or eggs, though this predation is less frequently documented than that by mammals and birds.
Red Squirrel Anti-Predator Behaviors
The red squirrel has developed sophisticated anti-predator behaviors. One primary defense is the use of predator-class specific alarm calls, which acoustically differentiate between aerial and terrestrial threats. An aerial threat, such as a hawk, triggers a high-frequency, low-amplitude “seet” call that is difficult for a raptor to localize. In contrast, a ground-based threat, like a fox or marten, elicits a louder, wide-bandwidth “bark” call that immediately alerts other squirrels.
When a threat is perceived, the red squirrel engages in rapid evasion, using its long tail for balance as it runs along branches or spirals around tree trunks. They also show a trade-off between feeding and vigilance, spending less time foraging and more time being alert when they detect predator cues. The squirrel utilizes the densest parts of the canopy for cover, reducing its visibility to raptors and avoiding open forest edges where it is more exposed.