Content for this page researched and created by Kirstin Pine.

Identification

The Pine Siskin (Carduelis pinus) is about five inches in length and 0.53 ounces (about 15 grams) in weight, with a wingspan of approximately nine inches (Sibley 410).  According to the Global Biodiversity Information Facility, Pine Siskins belong to the Animalia Kingdom, the Phylum Chordata, the Aves Class, the Order Passeriformes, the Fringillidae Family, the Genus Spinus, and the Spinus Pinus Species.

The colors of the Pine Siskin are rather distinct.  The wings of this bird are entirely brown with noticeable streaks of yellow (Alderfer and Rosenberg 640).  Distinguishing between male and female Pine Siskins might be difficult, as their colors seem rather similar, but there are some differences.  The backs of male Pine Siskins are brown with a whitish and coarse, dark streaking on the belly.  The female Pine Siskins are similar to the males in appearance, but their tails are greatly reduced in color (Alderfer and Rosenberg 640).  Although the male and female Pine Siskins are similar to one another in color, their distinct coloring helps differentiate between them and other Finches.  Fretwell and Starzomski stated that the bill shape of the Pine Siskin is also rather unique, as it is thinner and more pointed than the bills of other finches.  Identifying a Pine Siskin can be challenging because “although it is patterned like a sparrow, its shape, actions, and call-notes all reveal that it is really a Goldfinch in disguise” (Kaufman).  Kaufman also notes that Pine Siskins, with their relatively stocky build have short, forked tails and sharply pointed wings.

Behaviors and Habits

Feeding Habits

During the non-breeding season, Pine Siskins form large flocks and can commonly be found at seed feeders (Alderfer and Rosenberg, 640).  Because Pine Siskins are primarily seed-eaters, the species can be found responding to the availability of seeds on coniferous trees such as the Eastern Hemlock, Red Spruce, and several species of Pine trees, such as the Eastern White Pine (Gross).  Sibley adds that the Pine Siskin feeds on the buds and seeds of Birches, Alders, and other trees, while also consuming small insects (410).  In order to find food, Kaufman states that Pine Siskins will occasionally hang upside-down to reach seeds while scavenging vigorously through trees, shrubs, and weeds.  The Cornell Laboratory of Ornithology says that even though Pine Siskins prefer seeds from coniferous or mixed coniferous and deciduous forests, they are rather resourceful and adjustable when it comes to foraging for seeds.  Vuilleumier describes Pine Siskins as being vicious fighters at feeding tables which are primarily nomadic by nature with a fearless, high energy (553).  Flocks of Pine Siskins frequently will make a quick departure from a region if they are not satisfied with the food supply (Vuilleumier 553).

The Pine Siskin has a lifespan of approximately “ten years” (Vuilleumier 553).  In a study completed by Knutie and Pereyra, it was found that the “stress-induced elevation of plasma corticosterone and the relationship with body condition [were] consistent with a possible role of this hormone in modulating foraging activities…” (479), meaning that Pine Siskins secrete a hormone when they are experiencing high levels of stress that increases their need to find food.

Reproductive Habits

Kaufman states that courtship and the formation of pairs might begin in winter flocks, taking place from “February to August” (Vuilleumier, 553).  This process starts when the male Pine Siskin sings and flies in circles with his wings and tail spread widely above the female Pine Siskin (Kaufman).  Female Pine Siskins build the nest which consists of a large but shallow cup of twigs, grass, bark, and rootlets that is lined with moss, animal hair, and feathers (Kaufman).

The female Pine Siskin lays a range of eggs from about two to five, incubating them for approximately thirteen days (Kaufman).  BirdWeb states that the young leave the nest after thirteen to seventeen days, although the parents continue feeding them for about three more weeks.  In Koenig’s study which analyzed the reproductive patterns of Boreal Birds, he found that “factors in addition to food play[ed] an important role in both causing” (725) and coordinating increases of reproduction within this species.  To further emphasize the results of Koenig’s study, Watts and Hahn found that access to seeds had a positive effect on the affiliation of pairs of Pine Siskins, in addition to demonstrating that food is a powerful stimulus for the launch of reproductive development in this species (259).  In addition to their original study, Watts et al. completed another study to examine the influences of reproductive development in male and female Pine Siskins.  They found that the extent of affiliation within a pair of Pine Siskins corresponded to the extent of reproductive development in females, but not in males (39).  Therefore, reproductive timing in females appears to be sensitive to both the presence of a potential mate and the relationship that the female Pine Siskin has with the male.

Flight Patterns & Voice Calls

BirdWeb states that because Pine Siskins are similar to many other Finches, they also have an undulating flight and often make aerial contact calls.  These calls sound like a rapid jumble of husky notes (Sibley 410).  Vuilleumier adds that the flight of Pine Siskins can be characterized by a quick series of wing beats followed by closed-winged glides (553).  In Coutlee’s study on the vocalizations in the Genus Spinus, she found that the contact and courtship calls were the most distinctive for each species (556).  She also found differences between male, female, and juvenile Pine Siskins.  Juvenile females give a rhythmic food-begging call, while juvenile males give a warbling sub-song, and adult males produce a full song, which is used during territorial and reproductive activities (Coutlee 556).

Distribution

Pine Siskins can be found in a wide variety of locations.  Alderfer and Rosenberg state that Pine Siskins are widespread throughout coniferous forests across the Boreal zone of Canada and across the Northern United States of America in addition to mountainous areas of the West (640).  The location of Pine Siskins also varies from summer to winter.  Fretwell and Starzomski note that in winter, Pine Siskins are commonly found in coniferous and mixed coniferous-deciduous forests, while in summer, they will appear in shrub and field areas, branching out from its preferred habitat to find seeds wherever they are available.  Because of the versatility in locations that Pine Siskins may be found in, Kaufman says that their conservation status is widespread and abundant.  The abundance of Pine Siskins comes as a result from the species breeding from Alaska across Southern Canada, South through the Western United States, including Missouri, Indiana, Ohio, and New Jersey, and through the Appalachians to North Carolina and Tennessee (McWilliam and Brauning, 457).  McWilliam and Brauning also observe that Pine Siskins are abundant in Pennsylvania in some years, while they are scarce in other years; however, winter flocks are found almost consistently in the Northern Mountains (457).  The vast breeding locations leads Vuilleumier to believe that the Pine Siskin’s status is secure (553).  Through Alvarez et al.’s study, they found that the Pine Siskin is a rather common songbird that “shows relatively phenotypic uniformity across the North American continent.”  Beckman and Witt found that climatic cycles during the Pleistocene contain one of the main irregular causes of bird diversification in South America, involving Pine Siskins.  The distribution of Pine Siskins is not only vast across the United States of America, but also throughout other countries, like Canada, and other continents, like South America!

Migration Patterns

Similar to the distribution of Pine Siskins, the migration patterns of this species vary as well.  In the winter, the status and distribution ranges irregularly from year to year, mostly due to inconsistent food supply, and therefore, Pine Siskins can be found practically anywhere (Alderfer and Rosenberg, 640).  McWilliam and Brauning learned that the pattern of movements that Pine Siskins had into Pennsylvania has changed very little over the last few years (458).  With the change of the seasons, Pine Siskins’ migration patterns also change.  For example, BirdWeb states that in the winter, Pine Siskins can be found in many types of semi-open areas, including the edges of forests and in weed-filled fields.  With the variety of locations that Pine Siskins are found in in winter, they can be considered to be rather irruptive and wandering in their distributions, even though they are generally considered resident throughout the other seasons (BirdWeb).

In Arnaiz-Villena et al.’s desire to discover the ancestors of New World Siskins, they found that the Pine Siskin would have followed its ancestors’ North to South migrations across all of North America about 12,000 years ago.  Watson et al. made the first documented observation involving the Pine Siskin’s migration pattern.  By detecting night flight calls of Pine Siskins, Watson et al. found that these birds were likely undergoing nocturnal migration.  They stated that nocturnal migration may be a facultative migration strategy among the Fringillidae that occurs only during the years in which large irruptive movements of Pine Siskins take place.  In accordance with their observations, Watson et al. states the fact that “nocturnal migration is a common strategy among all North American Passeriformes.”

Diseases

Disease is something that unfortunately affects all forms of life and Pine Siskins are no exception.  Locke et al. found that salmonellosis has been receiving increased recognition as a cause of mortality among wild birds, particularly those that visit bird-feeding stations, such as the Pine Siskin.  Locke et al. identified sick Pine Siskins as appearing weak and depressed, with ruffled feathers and occasionally marked diarrhea.  Neurological signs that were present before death in these birds included ataxia, weak flight, and tumbling over.  Through their work, Locke et al. concluded that backyard bird-feeding stations can serve as a cause for serious disease outbreaks among wild birds.

General References:

Alderfer, Jonathan K., and Gary H. Rosenberg. “Fringilline and Cardueline Finches.” National Geographic Complete Birds of North America, edited by Jonathan Alderfer, National Geographic, Washington, D.C., 2006, pp.640.

Fretwell, Kelly, and Brian Starzomski. “Pine Siskin – Spinus Pinus.” Biodiversity of the Central Coast, The Starzomski Lab: Research and Teaching, 2013, http://www.centralcoastbiodiversity.org/pine-siskin-bull-spinus-pinus.html

Gross, Doug. “The Invasion of the Pointy-Beaked Finches:  Pine Siskins Are Here!” Pennsylvania eBird, Audubon and Cornell Lab of Ornithology, 4 March 2015, http://ebird.org/content/pa/news/the-invasion-of-the-pointy-beaked-finches-pine-siskins-are-here/.

Kaufman, Kenn. “Pine Siskin.” Audubon, National Audubon Society, 4 March 2016, http://www.audubon.org/field-guide/bird/pine-siskin.

McWilliam, Gerald M., and Daniel W. Brauning. “Fringillidae: Finches.” The Birds of Pennsylvania. Cornell University Press, Ithaca, NY, 2000, pp. 457-458.

“Pine Siskin.” BirdWeb, Seattle Audubon Society, http://www.birdweb.org/birdweb/bird/pine_siskin.

“Pine Siskin.” Identification, All About Birds, Cornell Laboratory of Ornithology, 2015. https://www.allaboutbirds.org/guide/pine_siskin/id.

Sibley, David. “Finches.” The Sibley Field Guide to Birds of Eastern North America, 1^st ed., Alfred A. Knopf, Inc., New York, 2003, pp. 410.

“Spinus Pinus.” Global Biodiversity Information Facility, GBIF, 25 July 2016, http://www.gbif.org/species/5231635.

Vuilleumier, François. “Finches.” Birds of North America, 1^st ed., Dorling Kindersley (DK), New York, NY, 2009, pp. 553.

Scientific References:

Alvarez, Sofía, Jessie F. Salter, John E. McCormack, and Borja Milá. “Speciation in Mountain Refugia: Phylogeography and Demographic History of the Pine Siskin and Black‐Capped Siskin Complex.” Journal of Avian Biology, vol. 47, no. 3, 2016, pp. 335-345, doi:10.1111/jav.00814.

Arnaiz-Villena, Antonio, Valentin Ruiz-Del-Valle, Raquel Reguera, Pablo Gomez-Prieto, and Juan I. Serrano-Vela. “What Might Have Been the Ancestor of New World Siskins?” The Open Ornithology Journal, vol. 1, pp. 46-47, doi:10.2174/1874453200801010046.

Beckman, Elizabeth J., and Christopher C Witt. “Phylogeny and Biogeography of the New World Siskins and Goldfinches: Rapid, Recent Diversification in the Central Andes.” Molecular Phylogenetics and Evolution, vol. 87, 2015, pp. 28-45, doi:10.1016/j.ympev.2015.03.005.

Coutlee, Ellen L. “Vocalizations in the Genus Spinus.” Animal Behaviour, vol. 19, no. 3, 1971, pp. 556-565, doi:10.1016/S0003-3472(71)80112-4.

Knutie, Sarah A., and Maria E. Pereyra. “A Comparison of Winter Stress Responses in Cardueline Finches. The Auk, vol. 129, no. 3, 2012, pp. 479-490, doi:10.1525/auk.2012.11241.

Koenig, Walter D. “Synchrony and Periodicity of Eruptions by Boreal Birds. The Condor, vol. 103, no. 4, 2001, pp. 725-735, http://ezaccess.libraries.psu.edu/login?url=http://search.proquest.com/docview/18278446?accountid=13158.

Locke, Louis N., Robert B. Shillinger, and Teresa Jareed. “Salmonellosis in Passerine Birds in Maryland and West Virginia.” Journal of Wildlife Diseases, vol. 9, 1973, pp. 144-145, doi:10.7589/0090-3558-9.2.144.

Watson, Michael L., Jeffrey V. Wells, and Ryan W. Bavis. “First Detection of Night Flight Calls by Pine Siskins.” Wilson Journal of Ornithology, vol. 123, no. 1, 2011, pp.  161-164. Wildlife & Ecology Studies Worldwide.

Watts, Heather E., and Thomas P. Hahn. “Non-Photoperiodic Regulation of Reproductive Physiology in the Flexibly Breeding Pine Siskin (Spinus Pinus).” General and Comparative Endocrinology, vol. 178, no. 2, 2012, pp. 259-264, doi:10.1016/j.ygcen.2012.04.023.

Watts, Heather E., Bruce Edley, and Thomas P. Hahn. “A Potential Mate Influences Reproductive Development in Female, But Not Male, Pine Siskins.” Hormones and Behavior, vol. 80, 2016, pp. 39-46, doi:10.1016/j.yhbeh.2016.01.006.

Image Gallery:

Flickr. Yahoo. Web. 14 September 2016. https://www.flickr.com/search/?text=spinus%20pinus.

1. Pine Siskin (Spinus Pinus). Andrew C., 2014. (Free to share and adapt).
2. Pine Siskin. fishhawk, 2015. (Free to share and adapt).
3. Pine Siskin. Bill Mojoros, 2009. (Free to share and adapt).
4. Pine Siskin in Crab Tree. Elizabeth Pector, 2015. (Free to share and adapt).