Crossbills are unique birds that are found across North America, Europe, and Asia. Their distinctive crossed mandibles allow them to extract seeds from pine cones and give them their name. But where exactly do these interesting birds make their homes?
Crossbills in North America
There are several species of crossbill that live in North America. The most widespread is the red crossbill, which can be found across Canada and the northern United States. Red crossbills live in coniferous forests, favoring pines, spruce, hemlock, and larches. They are absent from the southern U.S. where these trees do not grow.
Other crossbill species found in North America include:
- White-winged crossbill – spruce forests of Canada and Alaska
- Hispaniolan crossbill – pine forests of Haiti and the Dominican Republic
- Mexican crossbill – pine and fir forests of Mexico
These crossbills live in specific types of forest habitat where they can find their preferred conifer species to feed on. The Hispaniolan crossbill, for example, relies on Caribbean pine in its island homes.
Red Crossbill Range
The red crossbill has the widest range of any crossbill species in North America. They breed across Canada and south to the northern tier of U.S. states:
States | Provinces |
---|---|
Washington | British Columbia |
Idaho | Alberta |
Montana | Saskatchewan |
Wyoming | Manitoba |
Minnesota | Ontario |
Wisconsin | Quebec |
Michigan | New Brunswick |
New York | Nova Scotia |
Vermont | Newfoundland and Labrador |
New Hampshire | |
Maine |
During winter, some red crossbills may wander southward if cone crops are poor in the north. They have been recorded as rare vagrants even to states like Kansas and Texas.
Crossbills in Europe and Asia
The common crossbill also lives across a large swath of Europe and Asia. Their breeding range extends from Scotland across Scandinavia and Russia to Siberia and Mongolia. Like in North America, they primarily inhabit coniferous forests, especially pine, spruce, and larch.
Other Eurasian crossbill species include:
- Scottish crossbill – native to the Scottish Highlands
- Parrot crossbill – northeast Europe and Russia
- Two-barred crossbill – Siberia and northeast Asia
The parrot and two-barred crossbills forage almost exclusively on Scots pine and Siberian pine. The Scottish crossbill feeds mainly on native Scots pine within its restricted range.
Winter Movements
Crossbills are nomadic and tend to wander widely outside the breeding season. This allows them to track uneven seed production in conifers from year to year.
For example, common crossbills may irrupt southward some winters if cone crops fail in the north. In some years, large numbers may appear as far south as England, northern Spain, Italy, and the Balkans. Asian crossbills like the two-barred may roam west in some years as far as Sweden and Finland.
Key Habitat Features
Although crossbills live across northern forests, they rely on certain habitat features wherever they occur:
- Mature conifer forests – Need older trees producing a large and steady cone crop.
- Multiple conifer species – Allow crossbills to switch food sources.
- Forest openings – Provide nesting sites in small trees or shrubs.
Different crossbill species show preferences for particular conifers. But most also feed on a variety of conifer species. This flexibility allows them to adapt if one tree has a cone crop failure.
Coniferous Forests
Crossbills are specialized for feeding on conifer seeds. So they are restricted to forests where conifers grow. The main types they inhabit are:
- Pine forests – Scots, ponderosa, lodgepole, whitebark pines.
- Spruce forests – White, black, and Norway spruce.
- Fir forests – Douglas, balsam, and grand firs.
- Larch forests – Western, Siberian, and European larch.
- Hemlock forests – Eastern and western hemlock.
Younger conifer forests tend not to support crossbills well. The trees need to reach mature seed-bearing age to provide a reliable food source throughout the year.
Adaptations for Conifer Feeding
Crossbills are finely adapted to locate and extract seeds from conifer cones:
- Crossed bill tip – Allows them to pry apart cone scales and remove seeds.
- Thick skull – Protects brain from forces exerted by opening cones.
- Counterpart bill sizes – Males and females have different bill sizes to feed on different cones.
- Agile feet – Can hang acrobatically while extracting seeds.
These adaptations allow crossbills to exploit conifer seeds extremely efficiently. They can play a keystone role dispersing and predating those seeds within northern coniferous forests.
Nest Sites
Crossbills nest very early while snow may still be on the ground. They choose unique nesting sites, often in odd locations:
- Old conifer snags
- Tree hollows
- Broken treetops
- Conifer plantations
- Small trees amid forests
This may reduce competition with other boreal songbirds that mostly nest later. It also takes advantage of crossbills’ climbing abilities.
Nest height can range from near ground level to over 100 feet high. But they favor lower, scrubby sites in openings for quicker access while carrying heavy cones to the nest.
Timing of Breeding
Month | Breeding Activity |
---|---|
January | Nest building begins |
February | Egg laying peaks |
March | Chicks hatch |
April | Fledging young |
May | Second nesting attempts |
Their early breeding maximizes time for young to develop before leaving the nest. It also lets adults take advantage of peak seed crops following cone maturation in spring.
Movements and Irruptions
Crossbills don’t migrate over long distances like many birds. But they are nomadic and prone to irruptive movements each year searching for productive cone crops.
This allows them to breed at almost any season if food is abundant. It also means they can abandon areas quickly if cone supplies fail.
Some patterns of crossbill movement include:
- Local wandering – Flocks range widely within boreal forests.
- Regional irruptions – May move south or east/west within a region.
- Continental invasions – Can irrupt in huge numbers out of normal range.
These movements track bumper cone crops on an almost continent-wide scale at times. Reports of crossbill invasions occur every few years.
Climate Change Impacts
Climate change may impact crossbill distributions and movements in the future by affecting coniferous forests:
- Shifting forest ranges – Conifers may decline in some areas and expand in others.
- Increased forest disturbances – Fire, insects, and droughts could disrupt conifer seed production cycles.
- Altered nomadic patterns – Could change if large-scale cone crop failures become more common.
Crossbills should remain widespread due to their ability to utilize different conifer species and move long distances. But local conditions for particular species may change, especially in southern portions of their range.
Conclusions
Crossbills are specialized birds uniquely adapted to extract seeds from conifer cones. They breed across northern forests of North America, Europe, and Asia wherever mature pine, spruce, fir, and larch grow.
Their crossed bills, nomadic habits, and early breeding allow them to take advantage of distant and unpredictable cone crops. Crossbills likely evolved these traits in response to the variable seed production cycles in their coniferous forest homes.