Corn Crake (Crex crex)

[order] GRUIFORMES | [family] Rallidae | [latin] Crex crex | [UK] Corn Crake | [FR] Rale des genets | [DE] Wachtelkonig | [ES] Guion de Codornices | [NL] Kwartelkoning

Subspecies

Physical charateristics

The distinctive call of the Corncrake is usually the only contact you will have with this elusive and declining species. If you are lucky enough to catch a glimpse it will probably be of a bird flying weakly away, with its rufous wings standing out and with its legs dangling behind it. Birds seen on the ground are quite distinctive, particularly the yellow bill and legs, grey facial stripes, dark back and rufous wings. They could almost be a cross between a Partridge and a Water Rail.

Listen to the sound of Corn Crake

[audio:http://www.aviflevoland.nl/sounddb/C/Corn Crake.mp3]

Copyright remark: Most sounds derived from xeno-canto

Range

Eurasia : Central, West

Habitat

Compared to other rails, Corncrakes prefer much drier habitats and do not prefer wet areas. In primaeval times, the species is assumed to have occurred especially in riverine meadows and lowland marshes with Carex, Iris and Typhoides vegetation. As these original habitats have become scarce, Corncrakes nowadays select secondary habitats mainly where vegetation is removed annually, e.g. by mowing, but also by grazing or burning. A large part of the population is therefore now strongly associated with agricultural grassland. The keyfactor determining suitable breeding habitat is vegetation structure, especially tall vegetation with provides dense cover and has a height of at least 20 cm (at the start of the breeding season), enabling the birds to walk through. Thus, too dense vegetation, or vegetation with a thick layer of dead plant material from previous years is avoided. Furthermore, the birds generally prefer open or semi-open landscapes. If these requirements are met, Corncrakes may be found in different habitats. Throughout the breeding range (floodplain) meadows are clearly preferred. In some countries, the species also inhabits subalpine meadows up to 1500-3000 m above sea level. In addition, agricultural
areas with crops are important habitats in countries like Germany and the Netherlands and also in several eastern European countries. Preferred crops are winter cereals and alfalfa (Netherlands), i.e. those crops which offer suitable cover at arrival on the breeding grounds. In some countries breeding is also reported in set-asides and fallow land

Reproduction

Relatively few bird species are adapted to nesting in open farmland. The corncrake however is one such species. The most important habitat component for corncrakes are hay-meadows. They make much use of tall marsh vegetation to build a nest.
Traditional corncrake breeding grounds are tall grass meadows or other tall grasses but some nest in silage fields, rough pasture and less frequently in marshes, peat bogs, gardens, cereal and rootcrops.
In contrast to other Rallidae, Corncrakes are serial polygynous. Males advertise for females with a distinct and loud, disyllabic crex crex call which is given almost continuously by night. Often, males associate closely as in dispersed lekking species. During pair formation, singing activity is reduced and singing is often heard during early morning or during daytime. Once the female has started a clutch, the pair-bond breaks and the males resumes singing again, often away from the initial territory. Incubation and parental care are done by females only. After about two weeks, the female abandons the brood, and often associates with a new male and starts a new clutch. Second clutches have been reported to occur until mid-July. Clutch size is about 10 eggs. Incubation time is on average 18 days. Chicks are flightless until about 35 days.

Feeding habits

The diet in the breeding season includes a wide range of invertebrates found on plants, and on and within the soil. In Germany and Poland birds mainly take relatively large insects (length 5-12 mm) (N. Schaffer unpubl.). Small vertebrates such as fish and amphibians are also taken occasionally. In Scotland and Ireland earthworms and molluscs are important in the diet (G. A. Tyler unpubl. data). The principal prey (beetles, other large insects, earthworms, snails, slugs) are widespread in habitats other than those used by Corncrakes, so it appears that the species has specialised more in the structure of the vegetation that it occupies than in the food it takes. During autumn and winter the birds take mainly seeds. Most birds arrive on the breeding grounds in May, females slightly later than males. The mean date of arrival across 28 European range-states is 21 May (30 April to 15 June).

Corncrakes are sequentially polygamous. Males advertise for mates, and probably defend territory, with a loud disyllabic song, given occasionally by day and almost continuously at night from tall ground vegetation. After being attracted to a singing male, the female associates closely with him for several days during which the male sings only infrequently (Schaffer & Munch 1993, Tyler & Green in prep.). The pair-bond breaks during egg-laying and the male then resumes singing, sometimes moving a considerable distance to a new singing area (Tyler & Green in prep.). The mean date of ceasing to sing over 24 European states was 8 July (12 June to 19 July), several weeks before the southward migration starts. Calling is heard only occasionally as late as September. Females may lay a second clutch later in the summer and may also move before doing so. Incubation and care of the chicks is by the female alone.

The nest is on the ground in dense vegetation, constructed from dead stems and leaves. The average clutch size is c.10. Nests are recorded from the second half of May to the first half of July in over half of 24 range-states; in 12 states nests are found over two months or more. Chicks are recorded from the second half of June to the second half of July in more than half of 21 states, with many states also reporting flightless chicks in August. The long period over which nests and chicks are reported suggests that production of two clutches per female may be widespread, while also being partly attributable to variation between states in the time at which breeding starts.

Observations in Scotland indicate that: incubation of first nests begins from c.20 May to 12 June and takes c.19-20 days; apart from the destruction of nests by mowing, nest success is remarkably high with 80-90% survival to hatching; chicks leave the nest soon after hatching and are fed by the female bill-to-bill; broods forage by day within 100-200 m of the nest; about half of first-brood young survive to independence (10-15 days old, flying at c.35 days) in broods in which at least one chick survives; all females which rear their first brood before mid-July incubate a second clutch for 16-18 days, starting 12 days after leaving the first brood, with a similar nest success to first broods; most eggs hatch by the end of July or early August; females stay with their second broods longer (15-20 days) and overall productivity is higher than in first breeding attempts due to better chick survival, with 60% of chicks surviving to independence (T. Stowe et al. unpubl.).

At two weeks of age the distinctive calls of young birds and the females can be heard, giving reliable evidence of breeding (Schaffer 1994).

Conservation

Data from ongoing (albeit modest) monitoring in Russia (which holds the vast majority of the global population) indicate that the predicted declines have not taken place and that numbers have remained stable since 2002 or are even increasing. Whilst it is difficult to accurately predict future trends owing to the species’s extensive range and differing climatic and agricultural conditions in different regions, it is thought that populations in key parts of the range in Russia and Kazakhstan are unlikely to change dramatically in the near future. The species has consequently been reclassified as Least Concern because global population declines approaching 30% (predicted in 2004) have not taken place, and there is little evidence to suggest that they will do so in the next 11 years (three generations). The reclassification has taken place on the basis of improved knowledge of the species’s global extinction risk, as opposed to a genuine recovery to favourable conservation status across its range. The species remains a high conservation priority in significant parts of its range (at both national and regional levels), and continued conservation interventions, research and monitoring are essential. Evidence of a downturn in its fortunes or adequately documented projections of imminent rapid declines would warrant a further review of its status.
Crex crex is a widespread summer visitor to middle latitudes of Europe, which
constitutes >50% of its global breeding range. Its European breeding population is
very large (>1,300,000 pairs), but declined substantially between 1970-1990. Although
many populations increased during 1990-2000, the species fluctuated in its Russian
stronghold, and was broadly stable overall. Nevertheless, its total population size
clearly remains far below the level that preceded its decline. Consequently, this globally
Near Threatened species is evaluated as Depleted in Europe.
The Corncrake is a medium-sized migratory Rallidae species which winters in southern and eastern Africa. The breeding range covers large parts of Eurasia, but distribution is scattered and in many countries the species has become rare. The late breeding season and strong association with tall vegetation for breeding habitat, have made Corncrakes very susceptible to habitat loss and intensification of agricultural practice. In nearly all parts of its breeding range, it has experienced dramatic declines, especially in the second half of the 20th century. The association with tall vegetation is a key-factor which determines distribution of the species. Without special conservation measures, this habitat has already been removed by mowing in the first part of the breeding season in large parts of the breeding range. Only in countries with lower agricultural pressure, often found in the eastern part of the breeding range, may breeding conditions still be favourable and populations thrive.

The Corncrake breeding range formerly extended over much of northern and central Europe between c.41N and at least 65N, extending into Asia in western Siberia up to 120E. More than half the world population may breed in Asia (Russia, Georgia, Iran, Afghanistan, Tajikistan, Kyrgyzstan, Kazakhstan and China). The distribution is now much restricted within the former range, and is fragmented in western Europe. In Europe, Corncrakes are found from sea-level up to 1,400 m in the Alps and 3,000 m in Russia. The Corncrake still breeds in 34 European states (its status in Albania is not known and it no longer breeds in The Former Yugoslav Republic of Macedonia and breeds only irregularly in Turkey). Only 10 states now have populations of more than 1,000 males. Nine of these are central and eastern European countries (CEEC), with more than 10,000 singing males in Belarus, Russia and probably Ukraine, and several thousand in Bulgaria, Estonia, Latvia, Lithuania, Poland and Romania. France is the only country in western Europe with over 1,000 males. Germany has the second-largest western population with c.800 singing males. Populations from Austria, Ireland, Italy, Sweden and United Kingdom are all significant in size, but those from other countries (Belgium, Denmark, Luxembourg, Netherlands, Norway, Spain and Switzerland) can only be considered relicts.

Migration

Almost wholly long distance migrant, although numerous Dec-Feb records from W Europe, especially in 19 th century when breeding population much larger. Main flyways into Africa: W route via Morocco and Algeria; and more important E route via Egypt; few cross Mediterranean between these flyways. Some, probably from E Palearctic, enter Egypt and Sudan via Arabia and Red Sea. Autumn movements Aug-Nov (peak Sept) in Europe; passes through Morocco and Egypt Aug-Oct (mainly Sept); arrives Sudan Sept-Oct and most pass through Kenya Oct-Dec; few recorded S of equator before mid-Nov. Most reach C & S Africa late Nov-Dec, and leave late Feb-Apr; return passage more rapid, birds crossing Mediterranean late Mar to mid-May; W Palearctic breeding grounds occupied from mid-Apr. Passage recorded Azerbaijan Sept-Nov and Apr-May. Occasionally winters Mediterranean basin and N Africa. Migrates at night, at low altitude; often strikes lighthouses. Vagrants to Canary Islands, Azores, Madeira, Iceland, Greenland (c. 20 records), North America (c. 17 records) from Baffin I along Atlantic coast and S to Bermuda; S & SE to India/Pakistan (2), Sri Lanka (3), Seychelles, and Australia (New South Wales and off W Australia); New Zealand record not accepted; in Africa very rare or vagrant to Libya (2), W Mauritania (2), Mali, SW Niger, Chad (2), Nigeria (4), W Somalia (4), Ivory Coast, Ghana, Cameroon, Gabon (3), Congo (3), Angola (2), W Namibia (1) and W Cape (1). High degree of vagrancy indicative of dispersive ability and of readiness with which birds are blown off course by opposing winds. The autumn passage of most of the world population appears to be concentrated through the Middle East and north-east Africa and especially Egypt. Corncrakes winter mainly in the savannas of south-central and south-east Africa, from southern Tanzania to northern South Africa; there are also some records from western Africa.

Distribution map