- 4.3–5.5 in
- 7.1–8.7 in
- 0.4–0.6 oz
- Slightly smaller than an American Goldfinch
- Chardonneret des pins, Tarin des pins (French)
- Piñonero rayado, Dominiquito piñero (Spanish)
- Every couple of years, Pine Siskins make unpredictable movements called irruptions into southern and eastern North America. Though they’re erratic, these movements may not be entirely random. Banding data suggest that some birds may fly west-east across the continent while others move north-south. For more, see this post from Project FeederWatch.
- Following a large irruptive winter flight, some individuals may stay near a dependable food source and breed far south of the normal breeding range.
Bird-banding projects are invaluable for tracking migrating birds, even though few bands are ever recovered for small birds like siskins. Nearly 675,000 Pine Siskins were banded between 1960 and 2011; fewer than 2,000 were later found. By contrast, about one-quarter of the nearly 5,000,000 geese banded in the same period were recovered.
- Pine Siskins get through cold nights by ramping up their metabolic rates—typically 40% higher than a “normal” songbird of their size. When temperatures plunge as low as –70°C (–94°F), they can accelerate that rate up to five times normal for several hours. They also put on half again as much winter fat as their Common Redpoll and American Goldfinch relatives.
- Pine Siskins protect their eggs from cold damage, too. The nest is highly insulated, and the female remains on the nest continuously, fed by the male throughout brooding.
- Pine Siskins can temporarily store seeds totaling as much as 10% of their body mass in a part of their esophagus called the crop. The energy in that amount of food could get them through 5–6 nighttime hours of subzero temperatures.
Pine Siskins generally nest in open coniferous or mixed forests, but also inhabit parks, cemeteries, and suburban woodlands, where they breed in ornamental conifers or deciduous trees. While they favor feeding in open forest canopies where cone seeds are abundant, they'll forage in habitats as diverse as deciduous forests and thickets, meadows, grasslands, weedy fields, roadsides, chaparral, and backyard gardens and lawns. They flock to backyard feeders offering small seeds. Mineral deposits can lure them to otherwise unattractive habitats like winter road beds that are salted to melt snow and ice.
As their name suggests, Pine Siskins have a fondness for the seeds of pines and other conifers like cedars, larch, hemlock, and spruce. They also feed on deciduous seeds like alder, birch, sweetgum, and maples. They eat the young buds of willows, elms, and maples, and the soft stems and leaves of weeds and even young garden vegetables. They'll glean the seeds of grasses, dandelions, chickweed, sunflowers, and ragweed. They forage for insects, spiders, and grubs from leaves and branch tips, and occasionally take insects from the air. Pine Siskins feed readily at backyard feeders, preferring smaller seeds without tough shells like thistle and oil sunflower, but they will scavenge fragments of larger seeds left by heavier-billed birds, and will occasionally eat suet. They also feed on mineral deposits, including ashes, road salt, and fresh cement. They have been seen drinking from sapwells drilled by sapsuckers.
- Clutch Size
- 3–5 eggs
- Number of Broods
- 1-2 broods
- Egg Length
- 0.6–0.7 in
- Egg Width
- 0.4–0.6 in
- Incubation Period
- 13 days
- Nestling Period
- 13–17 days
- Egg Description
- Pale greenish-blue with brown or reddish-brown spotting.
- Condition at Hatching
- Helpless, weighing just over a gram, eyes closed, with dark gray down on head and back.
Over the course of 5 or 6 days, the female builds a shallow saucer of twigs, grasses, leaves, weed stems, rootlets, bark strips, and lichens, 2.5–6 inches across. The male, who stays close, may contribute nest material as well. The female lines the 1 to 2.5-inch inner cup (up to 2 inches deep) with fur, feathers, grass, moss, or thistle down. She may complete the nest several days before egg-laying. Nests are only loosely attached to branches and can be vulnerable to gusty winds.
The female loosely attaches the nest toward the end of a horizontal branch, by preference in the middle heights of a conifer. The spot is usually well concealed by foliage, often by another branch directly above it. Pine Siskins often nest in loose colonies where neighboring nests can be just a few trees away.
Pine Siskins flit about in the topmost canopy of seed-bearing trees. They'll often cling upside down to branch tips to empty hanging cones of their seeds. Abundant seeds or tender shoots lure them to the ground to feed. Gregarious flocks are constantly atwitter with wheezy contact calls while feeding or during their undulating flight. Unusually convivial and unterritorial, they sometimes nest in loose colonies, continuing to forage in flocks away from the nests. Males sing from high perches and during circular courtship flights. Pairs may visit other pairs' nests before and after brooding. During brooding, the female stays on the nest and the male feeds her. Winter flocks and individuals can be aggressive around food sources, challenging competitors by lowering their heads, spreading their wings and tail, and making faint threatening call notes. Aggressive lunges are the next step and may result in fights that can carry competing siskins several meters into the air. Opportunistic Pine Siskins may forage close to heavier-beaked birds, gleaning fragments of larger seeds they can't crack themselves. And they'll hop on the downy seed heads of dandelions, trapping them on the ground for easy picking. Pine Siskins sometimes migrate in flocks of several thousand.
The huge, hard-to-predict movements of Pine Siskins each year make estimating population trends extremely difficult. Overall numbers seem large, but analysis of trends indicate their numbers may be declining, particuarly in western states. Loss of habitat from forest-clearing may be balanced by new commercially planted coniferous forests, and by the Pine Siskin’s willingness to nest in shrubs and ornamental trees. Domestic cats, red squirrels, hawks, jays, and crows can prey on adult birds or on their eggs or young. Dense flocks of Pine Siskins seem particularly vulnerable to outbreaks of salmonella transmitted at feeders (more on feeder maintenance). Studies have shown local impacts of DDT and related pesticides and cyanide from gold mining. Pine Siskins' fondness for mineral deposits can lure them onto dangerously busy roadways salted to melt ice and snow.
Irruptive. Pine Siskins' winter movements are erratic and depend partly on the state of cone crops in northern North America. About every other year, Pine Siskins irrupt, or move into central and even southern parts of the continent, but the timing and extent of these movements are extremely variable.
Pine Siskins flock to thistle or nyjer feeders and other small seeds such as millet or hulled sunflower seeds. They may hang around whole sunflower seed feeders if heavier-billed birds are messy eaters and drop seed bits. If your yard has plants or weeds with hardy seed heads, such as dandelion, Pine Siskins may feed there as well. They will occasionally eat suet.
Find This Bird
Spot Pine Siskins clinging to the ends of conifer branches, even upside down, to feed at cones—or look for an exceptionally streaky, small-billed finch at your feeder. Also, listen for a distinctive, harsh "watch-winding" call (also likened to the sound of slowly tearing a sheet of paper in two) amidst their constant flock twitters. Over much of the continent, Pine Siskins can be abundant one winter and gone the next.
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Snowbird Season. Story and photographs in Living Bird magazine.