This species is difficult to separate from the parrot crossbill and Scottish crossbill, both of which breed within its Eurasian range, as plumage distinctions from those two species are negligible, though the head and bill are smaller than in either of the other species. Care is needed in identification, especially in Eurasia, where the glip or chup call is probably the best indicator. The identification problem is less severe in North America, where only the red crossbill and white-winged crossbill occur. However, there has been debate as to whether different call types should be considered separate species. For example, the Cassia crossbill, occurring in the South Hills and Albion Mountains in Idaho, has been described as a new species (Loxia sinesciuris) because it shows a very low degree of hybridization with the red crossbill. There are also genetic differences between the call type populations. Nevertheless, few ornithologists have chosen to give these forms species status.