The bearded reedling (Panurus biarmicus) is a small, long-tailed passerine bird found in reed beds near water in the temperate zone of Eurasia.

[8] The bearded reedling is now placed in the monotypic family Panuridae that was introduced in 1860 (as the subfamily Panurinae) by Marc Athanase Parfait Œillet Des Murs.

The specific biarmicus is from "Biarmia", a Latinised form of Bjarmaland, today part of Russia's Arkhangelsk Oblast and Kola Peninsula (a result of confusion when the species was first described; the bearded reedling does not range into these areas).

[4][15] The bearded reedling is native to temperate Europe and Asia, ranging from Spain, France and the British Isles to the Manchurian region, but its distribution tends to be quite spotty because of its habitat preference.

[2] In Europe, it used to be limited to mid and low latitudes, also including Great Britain, but in the second half of the 20th century it has expanded north into Scandinavia, Finland and the northern Baltics.

[3][16][17] It is an occasional non-breeding visitor to Cyprus and Iran, and it has rarely been recorded as a vagrant to the west, south and east of its normal distribution in Portugal, North Africa, Israel, Kuwait, Pakistan, Japan and Korea.

However, some European populations tend to spend the non-breeding period (winter) to the south or southwest of their breeding (summer) range, making what potentially can be described as a short-distance migration, up to a few hundred kilometres long.

This is primarily seen in the northern half of the continent, but in no region does it appear to involve the entire population, with some birds partaking in such movements and some essentially staying year-round.

[2][18] Both adults and young may make eruptive dispersals outside the breeding season and in periods with limited food or cold weather bearded reedlings may perform other, most often local movements.

[4] Although typically found perched or climbing on reeds and similar types of vegetation, it readily hops on the ground, especially in swampy places or at water's edge.

[3] Unlike most birds, bearded reedlings undergo a complete post-juvenile moult, starting in late July–early September and ending with an adult plumage in October.

[23] Because of their well-camouflaged plumage and dense reed bed habitat, they are easily overlooked, but their presence is often revealed by their characteristic metallic "ping" call, which is used by bearded reedlings to maintain contact with each other.

[22] In juveniles of both sexes, the size of the loreal patch is an honest signal of body condition, but whether this plays a role in mate choice when pairs are first established is unknown.

[3][15][27] In captivity where not limited by the same conditions as in the wild, they may already begin to breed in late February and exceptionally there can be attempts of up to seven broods in a season, although it is doubtful that this many can be raised successfully.

[26][28] Mating is very frequent and to increase the chance of fathering a clutch the male bearded reedling has a relatively large and muscular cloacal protuberance that functions as a copulatory organ, which is unique among passerines.

[28] In the wild bearded reedlings are entirely non-territorial,[3][15] but those living under the more restricted space of captivity may show some territorial tendencies, though two pairs can still inhabit and breed in an aviary that covers a couple of square meters.

[24][29] In the summer, the bearded reedling mostly eats adult insects, their larvae and pupae, and other small invertebrates (springtails, spiders, snails, etc), typically taking rather slow-moving species.

[15] The stomach lining is strengthened, and from around September to December, bearded reedlings swallow gritting material, for example coarse sand or small gravel grains, which aids in grinding down the tough seeds.

For example, it first established itself as a breeder in Denmark and Sweden in the late 1960s and is now locally fairly common in both countries (but subject to large annual variations depending on severity of winters).

[3] In subsequent decades, the species has further expanded into northern Europe, with the first record in Estonia in 1978 and breeding being verified shortly after,[16] and it becoming established as a breeder in Finland in the late 1980s.

[19][30] The population has always fluctuated greatly depending mainly on the severity of winters and the availability of suitable reed beds, which commonly were harvested or drained, but collection of their eggs also played a role.

[38][41] In Ireland, the bearded reedling has historically been considered a rare accidental visitor, but in recent decades there have been confirmed cases of breeding in coastal southeastern parts of the island.