Mass destruction of sand martin nests by flood along the river Tisza in Hungary

Tibor Szép

Intense and extended raining in the watershed of the river Tisza during end of May and beginning of June 2006 caused destruction of 20 thousands nests of sand martin bred along the 560 km long section of the river in Hungary. The population breed along the river Tisza has lost the entire first clutch during the incubation period. The hatching has started only in the 20% of the nests during the flood and it is possible that 5-10% of the incubating birds, 1000 - 2000 individuals, has died as well when walls with nests collapsed by the increased water level.

Before the flood in 29th May 2006, survey of the densest part of the river between Tiszalök and Tuzsér (108 km) found 15880 nests (26460 holes) in 19 colonies, among which there were 8 colonies which size were over 1000 holes. For 6th of June 2006, every colony were flooded or the part of the wall above the water level has collapsed. The same situation is happened in the other part of the river. On the base of the population survey of the entire river in 2005 and the 60% increase of the population size since 2005 along the intensively studied section, the estimated population size along the Hungarian section of the river is around 20 thousands pairs.

It is very possible that most birds will try to make additional clutch in the sand pits and in other man-made artificial walls during June near the river but we could not exclude that many of these sand martins will try to form colonies in distant places. Success of the additional breeding is very important to reduce the loss and breeding colonies need more than average attention in this year. Proper reproductive success is essential for sustaining the sand martin population because in an average migration/wintering season 60% of the individuals die. During the last decades, the studied and other populations in Europe faced often with much higher mortality because of the adverse climate and habitat condition in the African areas.

Population size along the river Tisza between 1986-2006 (T.Szép)


Flood along the river Tisza during the breeding season is rare and occurred only 12 times during the last 100 years, in average every 8th year. The last this kind of "green" flood was in 1998. Then it occurred second half of June and destroyed the nests before the fledging, because the most nestlings were 10-20 days old only. Since that flood, the population size has not reached the former level.

This population is one of the largest and densest sand martin population in Europe which breed in the natural breeding habitat, in the yearly renewing perpendicular river banks. The size of this population varies between 10-37 thousands pairs on the base of the integrated monitoring study led by Tibor Szép (MME/BirdLife Hungary - College of Nyíregyháza) since 1986. This population give the 20-50% of the Hungarian population and has an important role for maintaining the sand martin population in the Carpathian Bend. In many European country the sand martin populations show decrease. In Hungary the population size has decreased with 50% since 1999, except the population along the river Tisza where the level was stable for this period.

The regular and intense flood of the river Tisza during early spring, March-April, produce large number of fresh and proper breeding wall yearly. This kind of habitat is very important for this species to reduce the large cost of ectoparasites. The extended, highly natural flood zone of the river, mainly in the Upper part above Tokaj, provide a very proper breeding habitat for sand martins. The reproductive success is higher in this area than in the distant man-made artificial habitats. The Upper part of the river Tisza is a Ramsar site and NATURA 2000 area partly because its importance for the sand martin population.

The sand martin protection group of the MME/BirdLife Hungary ask to survey the sand martin colonies and inform us on the next e-mail address about the known colonies in Hungary and neighboring countries.

Photos of the flood and sand martins

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