by Margaret Parodi
A recent sighting of a flock of Clark’s Nutcrackers in my neighborhood in Bigfork sparked my renewed interest in this bird; the flash of the white and black tail feathers caught my eye. They were feeding in trees and on the ground in a stand of Ponderosa Pines and were going after the seeds in the cones with raucous enthusiasm. Nutcrackers are distinctive, mostly grey with black and white wings and tail. The tail has a black band in the middle with noticeable outer white feathers. Nutcrackers are about the size of a jay (12 inches) and have a long, pointed bill and are a member of the Corvid family (crows and ravens). Clark’s Nutcrackers were named for Captain William Clark of the Lewis and Clark Expedition by the ornithologist Alexander Wilson who analyzed samples brought back from the expedition. Nutcrackers were originally thought to be a variety of woodpecker, probably due to their flight pattern which can be undulating and gliding and also because of feeding habits which can include digging in trees for insects. They are a gregarious bird and typically travel in small flocks and communicate noisily with a long, harsh “shraaaaaaa”.
Their primary range is in the high mountains of the Western United States and preferably forests that are partly open, especially whitebark pine forests. They are omnivores and eat a variety of seeds, berries, insects, bird’s eggs, and carrion. The majority of the food they eat is pine nuts, especially of the whitebark pine, which are high in protein and fat. Clark’s Nutcrackers have a mutualistic symbiotic relationship with the whitebark pine (beneficial to both). They have a bill that is especially designed to break open the cone, dig inside and remove the seeds and have a sublingual pouch to store seeds, as many as 90 at a time! The majority of the seeds are saved and cached for later use. Seeds are harvested in the late summer and fall and cached in the ground, mainly in open areas near nesting locations. The seeds are thrust into the ground about an inch deep with the pointed bill. Many thousands of seeds are stored for later consumption. As a member of the Corvid family, they are intelligent birds and can remember where they stored seeds. They are reliant on their memory for survival as they overwinter in the cold mountains. Scientists have discovered that nutcrackers have a larger hippocampus than birds that don’t cache. It is thought that one method nutcrackers use to find caches is by remembering angles between the caches and nearby landmarks (trees, rocks, etc.), that is, by triangulation.
The whitebark pine evolved to take advantage of the nutcracker seed dispersal and have cones with breakaway scales, seed retaining cones, and wingless seeds. Obviously, not all of the cached seeds are retrieved, and some germinate growing into new trees. There is some reason for concern about the nutcrackers survival because there has been a loss of whitebark pine trees due to the prevalence of white pine blister rust and mountain pine beetle. Glacier National Park has seen a marked decline in its whitebark pine stands due to these diseases. The US Fish and Wildlife Service recently proposed that whitebark pine be listed as a threatened species under the Endangered Species Act.
However, nutcrackers are resilient and do not completely rely on whitebark pine seeds. Insects can be snatched out of the air imitating flycatchers. A specialized jaw structure developed to pound and break pinecones can also be used to pound and probe dead wood for insects.
Courtship and nesting begin in late winter. Nests are typically on the outer branches of conifers. The clutch size is 2-6 eggs, incubation is 18 days, and the young remain in the nest for 20 days. The male takes his turn in the incubation and develops a brood patch on his chest. A brood patch is a patch of bare skin that some birds develop during the nesting season allowing more body heat to get to the eggs. The young are fed seeds from the caches by both parents.
According to the Cornell Laboratory of Ornithology populations appear to have experienced some declines in the last 50 years. This may be partly due to the prevalence of white pine blister rust. Since nutcrackers live in a fragile subalpine environment, they are especially vulnerable to climate change and loss of habitat as their range is pushed higher in elevation. Both the Clark’s Nutcracker and the whitebark pine are species worth saving.