HBW 10 - Species accounts: Dunnock (Prunella modularis)

11. Dunnock
Prunella modularis

French: Accenteur mouchet  German: Heckenbraunelle  Spanish:Acentor Común

Other common names: European Dunnock, Hedge Accentor, Hedge-sparrow

Taxonomy. Motacilla modularis Linnaeus, 1758, Europe = Sweden. Forms a superspecies with P. rubida and P. immaculata. Eight subspecies currently recognized.

Subspecies and Distribution.
P. m. hebridium R. Meinertzhagen, 1934 - Hebridean Is (W Scotland) and Ireland.
P. m. occidentalis (E. Hartert, 1910) - Britain (except Hebrides) and W France.
P. m. modularis (Linnaeus, 1758) - breeds N & C Europe E to Urals, S to Alps and Romania.
P. m. mabbotti Harper, 1919 - breeds SC France, Iberian Peninsula, Italy and Greece.
P. m. meinertzhageni Harrison & Pateff, 1937 - breeds S former Yugoslavia and Bulgaria.
P. m. fuscata Mauersberger, 1971 - mountains of S Crimea.
P. m. euxina Watson, 1961 - breeds N & NW Turkey.
P. m. obscura (Hablizl, 1783) - breeds Caucasus region, NE Turkey and N Iran.
Introduced (probably occidentalis) in New Zealand.

Prunella modularis Descriptive notes. 14·5 cm; 19-20 g. Male nominate race has smoky-grey head, neck, throat and breast; grey-brown cheeks with fine pale streaks; mantle and back warm brown with blackish-brown streaks, rump and tail duller brown and unstreaked; wings blackish-brown, warm brown margins of secondaries and wing-coverts, faint wingbar formed by pale tips of greater coverts; below, grey of chest fades through greyish-white breast to white on belly; breast side and flanks pale brown, streaked blackish-brown, undertail-coverts greyish-buff; iris reddish-brown; bill blackish; legs light reddish-brown. Female is very like male but less richly coloured, with, in particular, head and neck paler with brown wash, mantle less heavily streaked. Juvenile is generally less grey than adult, with general plumage tone buffer, head and underparts heavily streaked. Races differ mainly in coloration: hebridium is much darker than nominate, with darker grey head and breast, belly less white, more rufous tone on upperparts and more extensive streaking; occidentalis is intermediate between previous and nominate, with more extensive brown on hindneck and crown, no white on belly, darker brown flanks than nominate; mabbotti is close to nominate in appearance but darker and greyer, like previous except for paler underparts; meinertzhageni differs from last mainly in heavier streaking on mantle, greyer underparts; euxina is relatively pale above, lighter grey crown streaked with pale brown, brown (rather than black) streaks on mantle, also underparts more extensively grey, flanks less streaked; fuscata is similar to previous but darker, with better-defined mantle streaks, although still greyer than nominate, grey of underparts more extensive with just a little white on vent; obscura is brownest race, with buff wash on head, neck and belly, paler brown ground colour and streaks on upperparts, slight white scaling on throat and breast. VOICE. Male song, in bouts from exposed perch, rarely in flight, a short (2-4 seconds) but pleasant warble, sometimes surprisingly loud, containing trills and sharply modulated units; male has repertoire of 10-15 phrases, these mixed to form larger number of song types, one type usually sung several times before switching (switching more frequent in context of female attraction than in male-male duels); sharing of songs among neighbouring males results in local dialects. Male also has subsong with different structure. Female produces combination of trills or complex songs in context of mate attraction. Juvenile starts singing in first autumn, full song develops in following spring. Most familiar call "tseep", used for contact outside breeding season by both sexes, loud higher-pitched version as alarm; faint trills also used to maintain contact.
Habitat.Highly variable across range. Occupies scrub and stunted woodland in alpine, subarctic and tundra habitats in N & E; found in montane habitat to just above tree-line in parts of range, including spruce (Picea) and larch (Larix) forests up to 2200 m in Switzerland, birch (Betula), maple (Acer) and juniper (Juniperus) scrub to 2600 m in Caucasus, and juniper and rhododendron (Rhododendron) scrub to 2000 m in Pyrenees. In N of range, found mostly in coniferous, broadleaf and mixed forests, particularly alongside water; in Bialowieza Forest (Poland-Belarus) also in mixed forest, particularly with alder (Alnus), ash (Fraxinus) and spruce. In W of range, from UK, Belgium and W Germany S to Iberia, mainly in lowlands, exploits managed woodland with thick understorey, hedges and farm woodland, suburban and urban gardens, parks and any other habitat with scrubby vegetation; shift to lowlands from likely ancestral habitat in alpine and subarctic regions unique within family. Introduced populations in New Zealand have successfully colonized scrub and woodland habitats from sea-level to 1600 m.
Food and Feeding. Diet largely arthropods, supplemented by seeds in winter; in Britain, volume of seeds in faeces was 90% in February, 0% in April (52% across year). Household scraps (e.g. suet, breadcrumbs) also taken. Proportions of different invertebrates in diet vary across range and with season; beetles (Coleoptera, especially of families Carabidae, Curculionidae, Scarabaeidae, Chrysomelidae and Staphylinidae) and spiders (Araneae) generally dominate, but springtails (Collembola), stoneflies (Plecoptera), orthopterans, earwigs (Dermaptera), bugs (Hemiptera), lepidopterans, scorpion flies (Mecoptera), flies (Diptera), hymenopterans, harvestmen (Opiliones), pseudoscorpions (Pseudoscorpiones), small snails and earthworms also taken. Plant food equally diverse, includes seeds of, among others, docks (Rumex), legumes, pines (Pinus), birch, nettles (Urtica), poppies (Papaveraceae), primrose (Primula), grasses, sedges (Cyperaceae), willowherb (Epilobium) and thistles (especially Cirsium); also berries of heaths (Ericaceae), bramble (Rubus), holly (Ilex) and elder (Sambucus nigra). Nestling diet similar to spring-summer diet of adults; coleopterans, dipterans and spiders in 50-75% of faecal samples in Britain; peak in lepidopteran larvae (83%) recorded in Jun; young also fed with seeds, including those of Norway spruce (Picea abies) in Russia. Forages chiefly on ground under cover of bushes and other vegetation, by gleaning or sorting through leaf litter; occasionally probes soil; rarely takes prey in flight. In winter, often forages beneath birdtables, but rarely seen on raised platforms. Spends 94% of time in foraging in Jan, 54% in May (more when feeding young). Usually feeds alone; in winter, may gather in small groups at rich food sources.
Breeding. Breeds Mar-Jul over much of range, May-Aug in Russia; two broods, occasionally three, per season. Following account based on detailed study in Cambridge, UK. Mating system variable, in sample of 254 cases monogamy 42%, polygyny 4%, polyandry 30%, polygynandry (2-3 males with 2-3 females) 24% (monogamy, polyandry and polygynandry occur also in low-density populations in Finnish spruce and birch forests); female territories (c. 0·2-0·7 ha) exclusive, defended by one male or, in shared territory (c. 0·3-0·7 ha), by 2-3 males. On shared territory, dominant (alpha) male guards and copulates with female, subordinate (beta) male competes and sometimes copulates; high copulation rate (0·5-2·5 times per hour), preceded by cloaca-pecking display; female encourages beta male to mate. Nest, built by female alone, a cup of twigs, stems, roots, grass and moss, lined with hair, wool, sometimes feathers, placed 0·5-3·5 m above ground in bush, hedge or tree. Clutch 3-6 eggs; incubation by female alone, period 12-13 days; of 264 broods, 8% fed by female alone, 59% by female and one male, 33% by female and two males; male care influenced by share of matings, hence paternity of brood; seeds fed by regurgitation, invertebrates fed bill-to-bill; total rate of nestling feeds varies with mating system, c. 12 per hour for pair-fed brood and c. 15 for trio-fed brood of 10-day-old chicks; nestling period 11-13 days. Productivity per successful brood varies with male care, from 0·8 fledglings (female alone) to 2·4 (female with one male) and to 3 fledglings (female with two males); c. 30% of all breeding attempts and c. 15% of hatched broods fail as a result of predation, including by cats, crows (Corvidae) and mustelids. Brood parasitism by Common Cuckoo (Cuculus canorus) rather frequent, c. 2% of nests in UK.
Movements. Resident, altitudinal migrant, partial migrant and total migrant. Fennoscandian, Russian, Polish, N German and other NE populations (nominate race) migrate to Turkey, S Russia, and Mediterranean region from SW Iberia E, including islands, to Israel and N Egypt; passage to N Africa regular, but involves few individuals. Recoveries indicate migration on broad front along NE/SW axis; autumn passage in Aug-Nov, spring return Feb-Apr. SE populations (Crimea and Turkey E to Iran) resident or partially migratory; some local altitudinal movement from Caucasus to Black Sea coast, but race obscura recorded as far S as Egypt. Populations in Britain, Ireland and France mainly sedentary, with local dispersive movements rarely exceeding 30 km. Sedentary in Iberia.
Status and Conservation. Not globally threatened. Generally common to very common. Estimated global population 10,500,000-23,200,000 pairs. Russian population estimated at 1,000,000-10,000,000 pairs; in rest of Europe c. 9,500,000-13,100,000 pairs, largest populations being in Britain (2,100,000), Germany (2,000,000) and Sweden (1,500,000). In prime habitat in England (Cambridge) reaches density as high as 640 adults/km²; 40-120 birds/km² in woodland and young plantations, habitats favoured across much of Europe. Population trends variable; in Finland, increased from c. 8000 pairs in 1950s to c. 400,000 pairs in 1980s, this attributed to changes in forest management creating dense scrubby habitat. Recently listed as a species of medium conservation concern in UK because of 25-50% decline in numbers since 1975; no specific factor identified as responsible.
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