Pine siskins live in coniferous or mixed coniferous-deciduous forests. Coniferous forests are made up of evergreen trees, which are primarily pine (Pinus), spruce (Picea), fir (Abies), and larch (Larix) trees that bear needles and cones. These temperate forests experience moderate levels of yearly precipitation. The forest floor is rich in nutrients from old tree and plant remains that promote moss and fungi growth. In a deciduous forest trees including oak (Quercus), beech (Fagus), birch (Betula), elm (Ulmus), maple (Acer), and linden (Tilia) tree. Deciduous forests experience all four seasons moderately and rely on year-round precipitation. Pine siskins live in coniferous or coniferous-deciduous habitats because they eat the seeds of coniferous trees and rely on the year-round protections of these trees and shrubs.
During the breeding season, siskins move to the outer edges of coniferous forests. In the summer, siskins can be found in brush on the edges of the forest because they eat the insects from nearby grasses and bushes. In fall and winter, the siskins leave the forest to seek food in open fields from herbaceous sources. Then they return to the forests to find shelter in the conifers and deciduous trees.
Siskins also inhabit suburban neighborhoods with sufficient trees for shelter. Suburban neighborhoods are a consistent food source for many birds due to the frequency of bird feeders in these neighborhood settings. (BirdLife International, 2016; Hill and McGraw, 2004; Hutto, et al., 1986; Nguembock, et al., 2009)
Pine siskins are songbirds ranging from 11 centimeters to 14 centimeters long, 12 grams to 18 grams in mass, and with wingspaces of 18 centimeters to 22 centimeters. Like most finches, siskins have moderately colorful plumage and sharp, triangular beaks specific for seed-eating from cones. Their breast is white and streaked with brown feathers. Their head plumage is made of smaller feathers with a more concentrated brown coloration. From their nape to rump, siskins display a similarly streaked pattern – dark brown tones intermixed with light brown and white feathers. Their feathers increase in length moving from anterior to posterior, which creates greater spaces in the distinct feather coloration moving from the head to the tail of the siskin.
While in flight or during mating events, siskins display bright yellow markings on their pointed wings and forked tails. Their wing feathers are brown, edged with white. A yellow band is present through the mid-wing when their wings are spread. This yellow line is indicative of hierarchical rank amongst siskins. When perched, yellow coloration is intermixed throughout the tucked wings, giving yellow markings on the left and right sides of the bird. Their tail feathers display bright yellow until mid tail where the feathers transitions to dark brown feathers edged in white. Their short pointed beak can range from brown to black and their legs and eyes are dark drown. This is not a sexually dimorphic species and juveniles present with similar markings as adults. Juveniles have pink beaks and buffy-yellow and light brown plumage until they have matured into their adult appearance by fall of their first year. Siskin eggs are 1.5 to 1.9 centimeters in length and 1.1 to 1.4 centimeters in width but there are no recordings of juvenile size post hatching. (BirdLife International, 2016; Humber, et al., 2009; Jardine, 2014; McCabe and McCabe, 1928; Yunick, 1976)
Pine siskins become sexually mature within their first year and females reproduce twice per breeding season. The siskin breeding season is flexible depending on food supply. They can breed from early spring through late summer. Siskins can breed in cold temperatures, which makes food their determining factor.
Prior to breeding, male siskins preform a courtship display by circling the canopy and singing a mating song that lasts about 13 seconds with various “zweeeee” sounds. The males continue to sing their mating song while showing off their bright yellow tail and wing markings until female siskins begin to “coo” back with a soft low-pitched call. Females mate with males that have an experienced song and offer food during copulation. During the breeding season, female siskins are polyandrous and breed with an average of two males. This breeding can occur once during each of two breeding cycles of the season or intermixed throughout the breeding period. Once the female has chosen a male, copulation is finalized and a pair bond forms. (BirdLife International, 2016; Johnson, et al., 1993; Perry, 1965)
After a pair bond forms, the female makes the nest and the male continues to sing and return with food. The nest is built between 3 and 12 meters off above the forest floor, located mid-branch of a coniferous or deciduous tree to ensure protection from predators. Though 3-4 eggs per nest is typical for siskins, females can produce 2-5 eggs per clutch. Female siskins incubate the eggs for 13 days while the male seeks food for his mating partner. Juvenile siskins weigh between 1 gram and 2.5 grams when the hatch (average 1.5 g). They remain in the nest for an average of 15 days before they fledge. Three weeks post-hatching.the juveniles can feed on their own and reach independence. Within their first year, the juveniles reach sexual maturity and can breed during the next spring breeding cycle. (Arnaiz-Villena, et al., 2012; BirdLife International, 2016; Johnson, et al., 1993; Luttrell, et al., 2001; Perry, 1965; Yamadaa and Bouldingb, 1998)
Male siskins invest in pre-breeding behaviors. Males expend energy during their courtship display as they sing and fly in circle above the females. They continue to expend energy resources during the breeding period and incubation time as they find food for the female. During the courtship and breeding period, the female builds the nest and then proceeds to lay and incubate the eggs and the male is feedig his mate every 30-60 minutes. The nest is composed of twigs, bark, roots, moss, fur, feathers, and other small semi-flexible objects and takes the female 5 to 6 days to construct. In suburban areas, the female uses other debris including, paper, string, cloth and cotton. Soft material lines the inside of the nest so as not to disrupt the eggshell. The external diameter of the nest is 10 centimeters on average and the internal diameter is 5 centimeters, with a nest height of 4 centimeters. Females build nests to be able to spread her wings and shield the juveniles from rain or bright sun during the 13-17 post-hatch days.
Once hatched, male siskins feed the females and then females feed the chicks via regurgitation. The males feed the female for 8 days after the eggs hatch and the majority of feeding takes place in the morning. (BirdLife International, 2016; Nguembock, et al., 2009; Perry, 1965)
Pine siskins live an average of 9 years in the wild. No other data are available regarding the lifespan of the pine siskin, and they are not kept in captivity. (BirdLife International, 2016)
Feeding behavior is very important for male-male, female-female, and male-female siskin relationships. Partnership feeding occurs year round in the siskin population. This feeding is most frequent during breeding season when males bring food to the females, but beak-to-beak feeding interaction occurs between same sex and heterosexual pairs after the breeding season ends.
Siskins are aggressive towards other species during breeding season and occasionally during throughout winter months. They antagonize many species including evening grosbeaks (Hesperiphona vespertina), red crossbills (Loxia curvirostra), and white-winged crossbills (Loxia leucoptera). When competition reduces after breeding season, siskins associate with American goldfinches (Spinus tristis), redpolls (Acanthis) and crossbills (Loxia). Body movement is indicative of the behavior that siskins display. Siskins are strong fliers and can escape competition quickly. Siskins are good at starting fights, as they can outmaneuver their competition. To leave the ground, they beat the air rapidly with their wings and take flight. Once airborne, they move their wings in a wave shape to maintain altitude. In confined spaces like dense canopies, they walk and hop across tree branches. Siskins will lunge when they feel threatened by a nearby species and depending on the surrounding forest density, they will fight from 3-4 meters in the air.
Siskins are an arboreal species that defend their nesting territory in the mid-range branch region of conifer trees and stack their nests in loose colonies. Before breeding occurs, the male circle above the canopy and sing to nearby females. Once a pair has formed, the male will continue to preform via song and flight, while the female builds the nest. The male will feed the female he is pursuing and continue to feed her throughout the duration of the egg incubation period. Once hatched, the juveniles are fed via regurgitation from the mother that was provided food from the male siskin. The male feeds the female for 8 days after the eggs hatch and the majority of feeding takes place in the morning. In between feeding events for the young, the mother will clean the fecal matter out of the nest by swallowing the nestlings excrement for 5-6 days after the young hatch. When sleeping, siskins tuck their heads between their shoulders to reduce surface area and conserve heat.
Siskins migrate in large groups, moving farther south when food resources become limited in their Northern location. Siskins do not follow the same migratory pattern each year, but instead navigate as a group to locations with the most abundant food opportunities. These locations range across continental America, along the lower portion of Canada, and Mexico. Siskins groups spread out once a new location is chosen. While they form small territories within the new area, siskins continue to interact with their flock by visiting other siskins’ nests. (BirdLife International, 2016; Hill and McGraw, 2004)
Pine siskins defend an area around their nest, about 0.6 to 1.7 meters in diameter, during the breeding season. This equates to about 0.9-2.3 square meters. (BirdLife International, 2016)
Male pine siskins rely on both their plumage and song to find a mate. Young males learn to sing long, complex melodies within their first year of life. Their mating songs last about 13 seconds and are used to gain the attention of a potential female. The males make sharp, high pitched, elongated “zweeeee” sounds when singing to the females. During feeding and flight, they use a wheezy “zreeeet” sound. Siskins make a short “zwee” sound during flight, as they call with each flap of their wings. When calls are not being used for mating purposes, the songs are quick and more aggressive. Females use a lower pitched husky call to males that can sustain over longer distances.
Pine siskins use their vision to increase scanning observations every second when they are feeding alone, as compared to feeding with one or more other siskins. Female siskins use vision to choose their mate. Unlike other bird species, female siskins distinctly choose a male with less exaggerated coloration. The females pick natural colors and less defined yellow markings on the male siskins.
Pine siskins are granivores, meaning their diet primarily consists of seeds. They use their pointed beaks to break open cones and extract seeds from coniferous trees. Siskins live in coniferous-deciduous forests because they eat the seeds of pine (Pinus), spruce (Picea), redcedar (Juniperus), and hemlock (Tsuga) trees. They will also eat seeds from a variety of weeds, such as chickweed (Strellaria media), ragweed (Ambrosia), and dandelions (Taraxacum). Siskins also feed on sunflower (Helianthus) seeds, which are used as bait in siskin studies to monitor behavior and feeding patterns. Balph and Balph (1979) noticed that siskins had acquired a unique feeding adaptation to help them overcome the tough outer shell of the sunflower seed. They observed siskins waiting for evening grosbeaks (Hesperiphona vespertina) to open the sunflower seeds and then the siskins would swoop in and eat the remaining seeds and seed fragments from the ground. Siskins will continue to feed this way until the grosbeaks become aggressive and then the siskins will return to eating seeds that they can husk independently. Pine siskins have also adapted to using bird feeders in suburban communities.
In the summer months, siskins will also consume insects as another food source. Over 2,000 spruce budworm (Choristoneura fumiferana) eggs were found in the stomach of a siskin during a study by Jennings and Crawford (reported in Dawson, 2014). Siskins use larvae and insects to feed to their young during the summer months when insects are more abundant. Siskins also eat road salt and sap from maple (Acer) trees. While siskins have multiple food sources, they are quick to alter their migratory patterns based on food source sustainability. Their breeding timeline is also flexible due to food availability. (Balph and Balph, 1979; Benkman and Lindholm, 1991; Dawson, 2014; Humber, et al., 2009)
Pine siskins are found in suburban areas with sufficient conifer canopy coverage because they have learned how to feed from bird feeder with small seeds. This food source provides an opportunity for domestic cats (Felis catus) to prey on siskins. Less common predators include the eastern red squirrels (Tamiasciurus hudsonicus), sharp-shinned hawks (Accipiter striatus), Cooper’s hawks (Accipiter cooperii), northern shrikes (Lanius excubitor), blue jays (Cyanocitta cristata), and American crows (Corvus brachyrhynchos). Brown-headed cowbirds (Molothrus ater) are amongst the most detrimental predators of the siskin. Female cowbirds lay their eggs in siskins' nests and fly away to a nearby tree to observe their egg’s surrogate nest. The mother cowbird will destroy the siskin nest if the siskin mother does not care for the cowbird egg. To avoid losing her nest, the female siskin will incubate the cowbird egg. (Astheimer, et al., 1991; BirdLife International, 2016; Hutto, et al., 1986; Jardine, 2014)
Pine siskins build nests in and inhabit the same geographical range as the brown-headed cowbirds (Molothrus ater). The cowbird does not build a nest or take care of its own young, but rather lays their eggs in siskins nests. Female siskins must incubate and care for the cowbirds eggs, which ultimately kills the female and juvenile siskins because they cannot compete with the feeding demands of a juvenile cowbird.
Pine siskins in Maryland, Oregon, Washington, British Columbia and Virginia are prone to carry bacteria salmonella (Salmonella typhimurium). They can also be carriers of the western blacklegged tick (Ixodes pacificus) that spreads Lyme disease spirochete (Borrelia burgdorferi). Other parasites infecting siskins include protozoans (Haemoproteus fringillae/orizovora, Haemoproteus, Leucocytozoon fringillarum, Leucocytozoon, and Trypanosoma avium). Feather mites include Proctophyllodes spini and rabbit ticks include Haemaphysalis leporispalustris. (Hill, 1976; Locke, et al., 1973; Nicholls and Callister, 1996)
Humans benefit from pine siskins because of ecotourism (bird watching) and because siskins consume forest insects. (BirdLife International, 2016)
Pine siskins may carry salmonella (Salmonella typhimurium). They can also be carriers of the western blacklegged tick (Ixodes pacificus) that spreads Lyme disease spirochete (Borrelia burgdorferi). these bacterial infections could be transferred to humans. (Dawson, 2014)
The IUCN Red List notes pine siskins to be of “Least Concern.” Siskins are protected under the US Migratory Bird Act. The US Federal List, State of Michigan List, and CITES offer no special status regarding pine siskins.
Many threats exist for these birds. Human interference may cause these birds to desert their nests and cause nest failure. Salt on winter roads could attract siskins to high-traffic areas. Dawson (2014) summarizes a few cases in which chemicals have killed siskins: in Idaho, the pesticide disulfotan killed birds, while gold-mining efforts and cyanide waste killed birds in South Dakota. Salmonella infections also could be spread by congregations at bird feeders.
Taylor Hawkins (author), Radford University, Alex Atwood (editor), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Karen Powers (editor), Radford University, Joshua Turner (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
living in landscapes dominated by human agriculture.
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
living in residential areas on the outskirts of large cities or towns.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
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