Swan images (Cygnus sp.) are the most common symbols at petroglyph sites on the eastern shore of Lake Onega, northwest Russia, where rock engraving most likely occurred around the mid-Neolithic period. At some sites they constitute over 60 per cent of all glyphs and they are the only glyph type common to all sites. The abundance of swan symbols at a given Onega site correlates most strongly with the abundance of cervids (mostly elk). There are even partially superimposed elk–swan engravings where part of one animal contributes to the other's body. There is evidence that, during the mid-Neolithic, early sites at Lake Onega were submerged by rising water levels, most probably coinciding with a period of climatic cooling. By that point, new petroglyph sites had been created further north by the Vodla river. Here swan images are larger and more abundant and other glyphs (such as solar/lunar) are absent. It is suggested that the swan was a supernatural symbol. Its prominence at the more recent Vodla sites may be indicative of greater importance being given to this species in the context of environmental change and an associated greater struggle for survival. Thus, the swan symbol may have been perceived by the local Neolithic Finno-Ugric people as an agent for the intended reversal or control of such external challenges, and selected from a pre-existing mythological framework based on its associated traits and perceived powers.