V.2. Protection of species and sites from invasive plants and harmful rodents

One principal purpose was to control the invasion of exotic plants. The prevalent invader plants are: Tamarix jordanis, Phragmites australis, Amaranthus spp, Chenopodium spp. and Sorghum haleness. Two ecologically acceptable control methods were utilized: biological control through controlled heavy grazing and mechanical mowing (see also V.5.3)

Mycocastor coypus (nutria), an exotic rodent imported from South America for its pelt, has became feral. It grazes aquatic plants, destroying delicate species such as Myriophyllum spictum, Utricularia australis and Nymphaea alba, of which only limited plant sources of are available. It is now hunted as a pest: in 1998, 112 were killed, and 132 in 2000. For the first time in the six years since the lake was re-flooded, Nuphar lutea planted inside its enclosure has successfully established itself outside of the protected environment as well. This process can be attributed to the decrease in the number of nutria. Voles also cause heavy damage to crops, especially to Medicago sativa (alfalfa).

An alternative to heavy poisoning is biological control. The most common methods applied in the Hula Valley are: (a) a lateral move irrigation system that attracts birds of prey. Systematic observations that were conducted in the area showed that, during irrigation, voles exit the soil and are predated by raptors (see also V.6.3); (b) The Barn Owl (Tyto alba) is a nocturnal predator that can be used to control voles To encourage Barn Owls to nest, farmers began to construct cages in the fields. Seven actively nesting owls were observed in 1998, twelve in 1999 and five nests in 2000. All 25 nestlings were ringed for further monitoring. These methods obviate poisoning, since that would kill the birds as well:

a. Lateral move irrigation system.
Medicago sativa (alfalfa), a species sensitive to voles, was irrigated by overhead spraying, which attracts birds of prey. Systematic observations in the irrigated area, showed that, during irrigation, voles exit the soil and are predated by birds standing on the irrigation equipment. The principal birds observed were Spotted Eagle (Aquila clanga), Lesser Spotted Eagle (Aquila pomarina), Common Egret/Great White Egret (Egretta alba), White Stork (Ciconia ciconia), Cattle Egret/Buff-Backed Heron (Bubulcus ibis), Black Kite (Milvus migrans).

b. Utilization of night predator birds - Barn Owl (Tyto alba)
The Barn Owl is useful as a natural means to control ground rodents. In 1998 a trial to encourage Barn Owl nesting by constructing cages in the field was carried out: a total of 13 cages were distributed in the area. Seven of them were occupied by nesting pair of Barn Owls. About 40 nestling were observed subsequently. In 1999, 15 additional cages were distributed in potato and peanuts fields of the Kibbutz Kfar Giladi, in an area is close to the western channel. There are a total of 28 cages in the area currently. The percentage of nesting was in 80% in the old cages and 20% in the new ones.