The Pine Siskin is a small, highly nomadic finch known for its erratic movements across North America, often appearing in large numbers when food is abundant. These streaky brown birds survive cold temperatures through metabolic adjustments and specialized foraging strategies. Understanding their diet is key to appreciating their specialized biology, from the seeds they seek in the wild to the foods they accept at backyard feeders.
The Core Diet: Seeds and Cones
The primary, year-round diet of the Pine Siskin consists of small, energy-dense seeds, especially those high in oil content. They display a significant preference for the seeds found within the cones of coniferous trees, such as spruces, pines, hemlocks, and larches. Their specialized, slender, and sharp-pointed bill allows them to probe between cone scales to extract the tiny seeds.
Beyond conifers, they also target the seeds of various deciduous trees, including birch and alder, often hanging upside down while feeding. This preference extends to the seeds of flowering plants and weeds, with favorites including thistle, dandelion, and ragweed. The siskin’s foraging behavior is highly social, with flocks moving efficiently to exploit localized seed crops, often causing them to travel widely when resources are scarce.
Dietary Shifts During Breeding Season
The nutritional requirements of Pine Siskins shift significantly during the breeding season to support the rapid growth of their nestlings. While adults maintain a base diet of seeds, they actively supplement it with protein-rich arthropods. This change is necessary because seeds alone do not provide the concentrated protein required for the development of young birds, who fledge approximately two weeks after hatching.
The siskins forage for insects, spiders, and grubs, gleaning them directly from the foliage and branch tips of trees. Specific prey items documented include soft-bodied insects like aphids and small caterpillars. Early in the spring, they also consume supplemental vegetable matter like the young buds of maples and elms, and have been observed drinking tree sap from sapsucker wells.
Attracting Pine Siskins to Feeders
Pine Siskins are frequent visitors to backyard feeding stations, especially during winter irruption years when natural food sources are low. To successfully attract them, offer seeds that mimic their natural preference for small, oily kernels. The most successful options are Nyjer seed (thistle seed) and hulled sunflower chips, which are easier for their small bills to manage than whole sunflower seeds.
The type of feeder used also plays a large role, as siskins prefer to cling while feeding, similar to how they hang from cones. Tube feeders with multiple small ports or mesh sock feeders designed for Nyjer seed are highly effective. Using multiple feeders and spreading them out can also help minimize crowding when large flocks descend on a single food source.
Prioritizing hygiene is necessary when feeding Pine Siskins due to their high susceptibility to bacterial diseases like Salmonellosis. Their highly social nature means that an outbreak can spread rapidly through a flock, with sick birds showing symptoms like lethargy or a fluffed-up appearance. The bacteria often grow in droppings or spoiled seed that accumulates at the feeding port or on the ground below.
Feeders should be cleaned and sanitized regularly, ideally every two weeks, or immediately if sick birds are observed. A sanitizing solution of one part liquid chlorine bleach to nine parts water is recommended; the disassembled feeder should be immersed for two to three minutes and allowed to air dry completely before being refilled. If a sick bird is confirmed, all feeders must be removed for a minimum of two weeks to force the birds to disperse and break the transmission cycle.