Red Crossbill

Loxia curvirostra

Order:
Passeriformes
Family:
Fringillidae
Sections

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Figures

Figure 1. Distribution of the Red Crossbill in North America.

Based on knowledge of major crossbill audio collections, conifer distributions, published literature, and documented records. Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue, and it also sometime includes a light dashed purple line to represent area where some call types are known to irrupt to, and nest, occasionally in small numbers) represents area where birds commonly move to when cone crops on key conifers fail in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s widespread cone failures on many conifers they typical use in core zones -- nesting is rare. Solid light yellow represents tertiary zone of irruption where movement is uncommon and breeding rare and local, and it only pertains to Type 2. Dashed Blue represents area of irruptive migration. Solid light purple dots represent known local breeding.

Figure 2. Annual cycle of breeding, migration, and molt for Red Crossbill.

Data from literature on North American Red Crossbills. Thick lines show peak activity; thin lines, off-peak.

Figure 3. Variation in bill size and shape among North American Red Crossbills.

Drawings based on adult male specimens collected in Sheridan, Wyoming (A) and Beech Creek, Pennsylvania (B). North American populations show a diverse range of bill sizes and shapes which vary between the extremes illustrated here. Bill size and shape are even more variable among European and Asian populations. The mandibles may cross either to the left or the right. Drawing by Dan Otte.

Figure 4. Known Flight Call types of North American Red Crossbills.
Figure 5. Co-occurrence of Red Crossbill Call Types.

Although multiple call types can be found in many regions of North America, multiple call types are regularly found in the same region only in the western United States and British Columbia. The greatest diversities and abundances of crossbills are found in the extensive and diverse conifer forests of the Pacific Northwest. Map compiled by Craig Benkman and Matthew A. Young.

Figure 6. Map of Type 1 Appalachian Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue, and it also sometimes includes a light dashed purple line) represents area where birds commonly move to when cone crops on key conifers fail in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s widespread cone failures on many conifers they typical use in core zones -- nesting is rare. Dashed Blue represents area of irruptive migration. Solid light purple dots represent known isolated breeding, and solid black dots represent vagrant records. Type 1 is the call type most associated with eastern North America. Map compiled by Matthew A. Young.

Figure 7. Map of Type 2 Ponderosa Pine Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue) represents area where birds commonly move to when cone crops fail on key conifers in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s massive widespread cone failures on many conifers they typical use in core zones -- nesting is rare. Solid light yellow represents tertiary zone of irruption where movement is uncommon and breeding quite rare, and it only pertains to Type 2. Dashed Blue represents area of irruptive migration. Solid light purple dots represent known isolated breeding. Type 2 is very likely the most widespread call type. Map compiled by Matthew A. Young.

Figure 8. Map of Type 3 Western Hemlock Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue, and it also sometime includes a light dashed purple line) represents area where birds commonly move to when cone crops on key conifers fail in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s massive widespread cone failures on many conifers they typical use in core zones -- nesting is quite rare. Dashed blue line represents area of irruptive migration. Solid black dots represent vagrant records. Type 3 make regular movements to the northeast and northern Rockies every few years. Map compiled by Matthew A. Young.

Figure 9. Map of Type 4 Douglas Fir Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue, and it also sometimes includes a light dashed purple line) represents area where birds commonly move to when cone crops on key conifers fail in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s massive widespread cone failures on many conifers they typical use in core zones -- nesting is quite rare. Dashed blue line represents area of irruptive migration. Solid light purple dots represent known isolated breeding, and solid black dots represent vagrant records. Type 4 make regular movements every few years to the Northern Rockies. Map compiled by Matthew A. Young.

Figure 10. Map of Type 5 Lodgepole Pine Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue) represents area where birds commonly move to when cone crops fail on key conifers in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s massive widespread cone failures on many conifers they typical use in core zones -- nesting is quite rare. Solid black dots represent vagrant records. Type 5 appears to form residency more readily, and irruptive migration is thought to be uncommon. Map compiled by Matthew A. Young.

Figure 11. Map of Type 6 Sierra Madre Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Primary Zone of Irruption (solid dark blue) represents area where birds commonly move to when cone crops fail on key conifers in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Solid black dots represent vagrant records. Appears to be resident across much of its range in Mexico, but more data is still needed. Map compiled by Matthew A. Young.

Figure 12. Map of Type 7 Enigmatic Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue) represents area where birds commonly move to when cone crops fail on key conifers in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s massive widespread cone failures on many conifers they typical use in core zones -- nesting is quite rare. Dashed blue line represents area of irruptive migration. Solid black dots represent vagrant records. Initially thought to be a western call type, but more data (map is provisional) is still needed on this call type since its status remains "enigmatic." Map compiled by Matthew A. Young.

Figure 13. Map of Type 8 Newfoundland Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. This threatened call type (ssp. percna) has recently been discovered in small numbers on Anticosti Island, Quebec. Red Crossbill recordings are needed from coastal areas of northern Nova Scotia and New Brunswick to determine whether it occurs there. Map compiled by Matthew A. Young.

Figure 14. Map of Cassia Crossbill (formerly Type 9).

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Type 9 was raised to species status (Cassia Crossbill) in 2017. Map compiled by Craig Benkman.

Figure 15. Map of Type 10 Sitka Spruce Red Crossbill.

Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Secondary Zone of Occurrence (solid light purple) represents area where lesser numbers of birds can be found many years with some regularity -- Small numbers of breeding birds present most years. Primary Zone of Irruption (solid dark blue) represents area where birds commonly move to when cone crops fail on key conifers in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. Secondary Zone of Irruption (solid light blue) represents area where birds move to only when there’s massive widespread cone failures on many conifers they typical use in core zones -- nesting is quite rare. More data is needed to determine how irruptive this call type is, map is provisional in the east. Map compiled by Matthew A. Young.

Figure 16. Map of Type 11 Central American Red Crossbill.

Based on knowledge of major crossbill audio collections, published literature, documented records and cone-ripening phenologies. Core Zone of Occurrence (solid dark purple) represents the area where key conifers are found and where birds can regularly be found utilizing those key conifers during most typical years -- Breeding is common in numbers the majority of years. Primary Zone of Irruption (solid dark blue) represents area where birds commonly move to when cone crops fail on key conifers in their core zones of occurrence – these areas often harbor conifer species most similar to those found in core zones, and in some years upon arrival, if cone crops are good on appropriate conifers, they can nest in small numbers. More data is needed on this call type. Map compiled by Matthew A. Young.

Figure 17. Four songs of Type 4 male Red Crossbill in Colorado.

Recorded by CSA 15 July 1994, at Gunnison County, Colorado.

Figure 18. Red Crossbill 'toop' calls by Type.
Figure 19. Cassia Crossbill (A and B) and Red Crossbill (C and D) flight calls.

A: Cassia Crossbill Flight Call, typical call, Cassia County, Idaho. B: Cassia Crossbill Flight Call, complex variation, Cassia County, Idaho. C: Red Crossbill type 2 Flight Call, Okanogan County, Washington. D: Red Crossbill type 5 Flight Call, Gunnison County, Colorado.

Figure 20. Relative abundance of Red Crossbill mostly during June in the United States.

Based on data from the North American Breeding Bird Survey, 2011–2015. See Sauer et al. (2017) for details.

Figure 21. Regional trends in Red Crossbills mostly during June in the United States.

Based on data from the North American Breeding Bird Survey, 1966–2015 (Sauer et al. 2017). Data show estimates of annual population change over the range of the survey; areas of increase are shown in blue and declines are shown in red. See Sauer et al. (2017) for details.

Recommended Citation

Benkman, C. W. and M. A. Young (2019). Red Crossbill (Loxia curvirostra), version 2.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.redcro.02