Accentors are small plainly colored birds, usually confined to mountainous regions. They are sparrow-like in appearance but with a more slender and pointed bill. The sexes are similar in plumage but males are larger (with longer wings and heavier) and a little brighter. Until recently they were thought to be most closely related to the thrushes. However, recent biological studies suggest that their nearest relatives are wagtails, pipits, sunbirds, sparrows (Pas-ser species) and the cardueline and fringe-line finches.
The accentors have the rare distinction of being almost exclusive to the Palearcticregion (i.e. Europe, Africa north of the Sahara and Asia north of the Himalayas). Fairly ubiquitous in this region is the Alpine accent-tor but it occurs only at high altitudes. This may have resulted in the evolution of many races or subspecies: eight or nine subspecies have been described. All species of accentor except the dunnockbreed in mountains: the Himalayan accent-tor can be found breeding at 5,000m above sea level; the Robin accent-tor is also found at high altitudes though it prefers to live in dwarf rhododendron another scrub, or in willows and sedge in damp meadow.
The range of the Siberian accentor reaches northwards beyond the taiga region, whereas one subspecies of the Black-throated accentor (P. atrogularis fagani), although native to Central Asia, is found further south in winter. The Maroon-backed accentor is found from Nepal to western China and shows a preference for damp areas deep in coniferous forest. Some of the accentors are migratory, others move only to lower altitudes in winter. The dunnock, however, is known to do both.
Unfortunately information about the behavior and breeding biology of the accentors is rare, except for the unlock, and even this common species has only recently been studied.
During the breeding season (late March to August) members of this species establish several different types of territory: solitary males, pairs of male and female, or male and female plus an additional male. Bigamy and bigamy plus extra males have also been recorded. It is unclear why some territories contain extra males, and suggesting a function for them is made more difficult by the fact that a pair of accentors with an additional male do not seem to produce more off-spring than a solitary pair. However, an extra male sometimes feeds the young. Mates with the female and with the other male defend the territory. Pairs with an extra male have significantly larger territories than do solitary pairs.
In all unlock populations so far examined there has been an excess of males. This may be because fewer females survive the winter because they have a lower place in the dominance hierarchies.
Another fascinating aspect of the behavior of the unlock is its unusual pre-copulatory display. During this display the female stands with her body horizontal tithe ground, her head slightly raised, her body feathers partly erected, her wings drooped (which she flicks occasionally), and her tail raised at an angle of 30 degrees which she vibrates rapidly from side to side.
In response to the female’s display the male makes tentative hopping movements from side to side at the rear of the female. At the same time he also makes pecking move-mints towards the female’s cloacae. The display lasts about 40 seconds and ends with the male jumping at a slight angle towards the female and the pair making contact with their cloacae for a fraction of a second.
The probable reason for such an elaborate display has recently become clear. Because the female can often be mated by either of two males with whom she shares a territory
her mate has to be certain that his mating has been successful. The elaborate pre-copulatory display may be
A method whereby he can safeguard the paternity of the offspring. The male’s pecking behavior appears to stimulate the female to eject any material she has in her cloacae. This material can contain sperm, i.e. the female’s mate can stimulate her to eject sperm from the extra male. (To prevent the extra male fromremating the male guards the female during the critical period.) It has been observed that the intensity of the male’s display increases with the likelihood of another male having just mated the female.