TY - JOUR AU - Tyrberg, Tommy PY - 1991/01/01 Y2 - 2024/03/28 TI - Crossbill (Genus Loxia) evolution in the West Palearctic – a look at the fossil evidence JF - Ornis Svecica JA - Ornis Svec VL - 1 IS - 1 SE - Research Papers DO - 10.34080/os.v1.19516 UR - https://journals.lub.lu.se/os/article/view/19516 SP - 3–10 AB - <p>The systematics of West Palearctic crossbills of Genus <em>Loxia&nbsp;</em>has long been disputed. The Scottish form <em>scotica</em> has been considered a species or a subspecies of either <em>Loxia curvirostra</em> or <em>L. pytyopsittacus</em>. The reason is the size and form of its bill which is intermediate between that of the two species. It feeds on pine cones as do four Mediterranean subspecies which also have larger bills than spruce feeding <em>curvirostra</em>. An examination of about 30 fossil Loxia records reveals that curvirostra type crossbills lived in South Europe and the Near East all through the last glaciation and that <em>pytyopsittacus</em> type crossbills lived in the Alps towards the end of the glaciation. These South European crossbills must have fed on Pine since no other conifers were available, and they must have been isolated from Siberian congeners. With the spread of Pines northwards with the retreat of the ice the crossbills followed. The fossils allow two alternative hypothesis depending on whether the large crossbills in the Alps are considered a species or not. If they were <em>pytyopsittacus</em> this species is rather old and both <em>curvirostra</em> and <em>pytyopsittacus</em> spread northwards at the end of the glaciation. One of the species must have gone extinct in Scotland and South Europe and possible <em>curvirostra</em> must have merged with curvirostra spreading with the Spruce from the east. On the other hand, if the Mediterranean crossbills of the Ice Age represent a single, variable species then all the large-billed forms, <em>pytyopsittacus</em>, <em>scotica</em> and the Mediterranean subspecies are descendants of the old “Pine” crossbills of South Europe.</p> ER -