This species breeds on small, shallow fresh (Llimona et al. 2014), brackish or slightly alkaline (Fjeldsa 2004) waters between 0.5 and 2 m deep and between 1 and 20 ha in area (Snow and Perrins 1998) with rich floating (Konter 2001), submergent and emergent vegetation (Fjeldsa 2004). Habitats include small pools, marshes with patches of open water and secluded sections of larger lakes and rivers (Llimona et al. 2014). In its wintering range the species frequents coastal inshore waters (Llimona et al. 2014) up to 10?20 m in depth (Fjeldsa 2004) including sheltered bays (Llimona et al. 2014), lagoons and estuaries (Ogilvie and Rose 2003). It may also occur on large lake and river systems south of its breeding range (Llimona et al. 2014, Fjeldsa 2004). The species breeds from April to August, generally in solitary isolated pairs. The nest is a platform of aquatic vegetation either floating and anchored to emergent vegetation, built from the lake bottom (where water is shallow) or built on rocks at water level. Clutch size can be between one to eight eggs but normally four to five in Europe. Its diet consists predominantly of fish and invertebrates such as adult and larval insects, crustaceans (Llimona et al. 2014), crayfish (Fjeldsa 2004) and crabs (Konter 2001), molluscs and worms. Fish and crustaceans are more important components of the diet during the winter when the species is at sea (Llimona et al. 2014). This species is fully migratory (Llimona et al. 2014) and travels over land in stages on a broad front, some populations only moving short distances to the nearest ice-free coast (Fjeldsa 2004).

Although the generation length for both EU and Europe regional assessments were calculated using the same methodology, new information arriving after the EU assessments were undertaken gave rise to an update in the generation lengths. This new information was then used for the Europe level assessments giving rise to a difference between the generation lengths used for the EU and Europe regions.

In Europe, this species breeds largely in Finland and Sweden, and also notably in Russia, Iceland and Norway.

Wintering grounds occur further south, including the North Sea, Adriatic Sea, Black Sea and the Caspian Sea (Llimona et al. 2014).

Conservation Actions Underway
CMS Appendix II (western Palearctic populations). EU Birds Directive Annex I. Bern Convention Appendix II. There are no known current conservation measures for this species.

Conservation Actions Proposed
Identify sites of international importance for the species and implement site protection. Populations should be closely monitored to determine whether numbers are stable or whether local declines are symptomatic of more widespread problems. Conduct survey work to accurately ascertain the current population sizes of both subspecies of horned grebe. Marginal populations in north-western Europe which have shown strong historical fluctuations should also should be monitored (O'Donnel and Fjeldsa 1997). Stricter legislation on oil drilling and transport should be enforced and mitigation measures against bycatch in fisheries implemented.