Marbled Teal (Marmaronetta angustirostris)
Small, grey-brown dabbling duck. Brownish body flecked with creamy-brown. Dark eye-patch and broad eye-stripe from eye to nape. No speculum. Elegant shape, slightly crested appearance and long neck and wings. Female slightly smaller. Characteristic low, slow flight. Similar spp. Pintail Anas acuta female is larger, lacks eye-patch and has scalloped flanks. Voice Squeaking jeep uttered by displaying males. Otherwise relatively silent.
Habitat needs are poorly understood. Marbled Teal mainly use shallow, eutrophic wetlands, typically with dense emergent and submerged vegetation. Fresh to saline wetlands are used, but there is some evidence of a preference for slightly brackish sites. More permanent wetlands seem to be favoured for breeding while newly flooded areas seem to be preferred outside the breeding season. Phragmites, glasswort (e.g. Salicornia) or Typha are typically dominant in favoured wetlands, especially when they offer densely vegetated, shallow areas that provide good cover. Many temporary wetlands that flood only in years of high rainfall are used throughout the life-cycle. This is particularly true in North Africa, where some of the most important breeding sites are dry in most years.
The current global distribution of the Marbled Teal is fragmented, with major centres of distribution in the western Mediterranean and tropical Africa (Spain, Morocco, Algeria, Tunisia, Senegal, Mali, Nigeria and Chad), the eastern Mediterranean (Turkey, Israel, Egypt and Syria) and western and southern Asia (Azerbaijan, Armenia, Russian Federation, Turkmenistan, Uzbekistan, Tajikistan, Kazakhstan, Iraq, Iran, Afghanistan, Pakistan, India, China). The first and last of these regional populations are found partly within the western Palearctic, while the second lies wholly within it. The movements that occur within and between these regional populations are very poorly understood and open to speculation. The only ringing data for Marbled Teal comes from the western Mediterranean.
On the basis of recent midwinter counts, the current world wintering population of Marbled Teal has been conservatively estimated at 34,000 birds. The western Mediterranean/tropical African population can be estimated at 3,000, with a 1993 count of 2,435 in Morocco and Algeria and several hundred birds probably wintering in tropical Africa. The eastern Mediterranean wintering population must be at least 600, given the fact that 200 pairs or more currently breed in Turkey and Israel. The south-west and southern Asian wintering population can be conservatively estimated at 30,000, with a 1992 count of 26,275 in Iran and Pakistan. Numbers present at many potential wintering sites in Asia are still unknown, particularly in Iraq, Afghanistan and the former Soviet Union, and this population is likely to have been underestimated.
The actual total world population immediately prior to the destruction of the marshes of southern Iraq was most likely to lie in the range 34,000-40,000, with a total breeding population of 8,000-13,000 pairs. Like those of other duck species, Marbled Teal populations must fluctuate considerably from one year to the next, and the above figures refer to estimates of peak population size within the range of current fluctuations. There are insufficient data to estimate the lower limit of this range, but it is likely to be less than 50% of the peak population. However, these figures for population size may already be out of date and a population crash is likely to result from the destruction of the Iraqi marshes since 1991, as this area may have supported over 10,000 Marbled Teal in the breeding season. Most birds breeding in Iraq were thought to winter in Iran, and there is evidence for such a population crash from the extremely low recent winter counts from Iran of 5,021 in 1993 and 1,919 in 1994.
The very few data on diet indicate a mixture of invertebrates and plant material (seed, shoots, leaves, roots, tubers) being taken. Marbled Teal feed mainly by dabbling, with upending observed very occasionally. Feeding activity is concentrated in beds of submerged macrophytes when these are available. The filter in the bill is not very fine, suggesting that Marbled Teal do not feed on plankton.
This species appears to have suffered a rapid population decline, evidenced in its core wintering range, as a result of widespread and extensive habitat destruction. It therefore qualifies as Vulnerable. However, data are scarce and some birds may have relocated to alternative wintering sites. Apparent increases in the western Mediterranean population probably reflect improved observer coverage rather than genuine changes. This population has suffered a long-term decline and widespread loss of habitat [conservation status from birdlife.org]
The mating system is monogamous, but is still poorly understood. Very few paired birds are observed in winter, and pairing occurs in early spring. The species is sexually monomorphic, and field observations in Spain suggest that males remain with females and their broods, playing a guarding role. The timing of nesting is variable, with 4-14 eggs laid from late April to the first half of July. Incubation takes 25-27 days. The time from hatching to fledging has not been recorded, but is probably 8-9 weeks. Brood amalgamation has often been observed, up to 32 ducklings having been recorded with one female. Communal nesting was formerly known.
Migratory and dispersive, but little understood in virtual absence of ringing. Apparently irregular at times, according to availability of shallow waters. Spanish breeders leave marismas temporarily in late summer; many records September to north-east near coasts and in Ebro delta.
The Marbled Teal is migratory across its range in the sense that it undergoes frequent movements across national frontiers. But it is largely nomadic, making unpredictable, non-cyclical and opportunistic movements in relation to rainfall and flooding patterns. Which themselves are highly unpredictable over most of the range. There is a general migration southwards in winter, but the timing and extent of such movements varies considerably between years .
There are very few data on moult behavior, but there is probably a full, flightless moult in late summer, followed by a partial moult into breeding plumage in late autumn/early winter, as with other dabbling ducks and pochards. Moulting flocks have been reported in Tunisia in the first half of July, while 10 moulting birds were reported in Uzbekistan on 17 June 1982.