V.6. Co-existence of agriculture and birds in the Hula Valley
V.6.1 Co-existence of agriculture and cranes in the Hula Valley.
For the past four years, intensive research on the topic of cranes in the Hula Valley has been conducted. Since the beginning of the present decade, their number has risen sharply (Fig. 11). Approximately 20,000 cranes pass the winter in the Hula Valley, between November and March. Dan Alon, The Avian Director of the Society for the Preservation of Nature (ISPN), conducted the research on this topic the cranes pass the night at Lake Agmon and during the day they spread over 6000 ha of land in the Hula Valley. They feed on remnants of peanuts, on Cyperus rotundus, and also on such crops as wheat and chick-peas, but the main damage they do is caused by trampling and pecking in search of invertebrates in the soil.
Hula Valley farmers, together with the ISPN and the Nature and National Parks Authority, the Ministry for the Environment and Project LIFE, are partners in a project whose aim is to minimize the damage caused by cranes, on the one hand, and to enable them to pass the winter in this country, for the sake of both conservation and tourism.
A great many visitors come to see the flocks of cranes, especially in the evenings, when the cranes congregate noisily at their rest-grounds at Agmon Lake and the Hula Nature Reserve, flying in formation. The project is based on closing some of the area to movement, including tourism. These are fields, which farmers have agreed to leave fallow that year, against compensation, and form part of a plan to establish “safari” areas of the Hula Project.
Data were taken from the databases of the ISPN and the Nature and National Parks Authority, and analyzed by the LIFE team.
Fig. 11: Number of Gray Crane observed in Israel in 1850-1999
Research has shown clearly that the reason for the rise in the number of cranes is the sharp increase in groundnut (peanut) cultivation in the Hula Valley. This crop is threshed in autumn, and the cranes arrive immediately after threshing to feed on the after growth that grows in the peanut fields, which yields from 1 kg/ha up to 50 kg/ha peanuts. At the same time, a small number of cranes feed on other seeds, especially from the after growth of corn.
Figure 12 shows the distribution of cranes according to crops in the Hula Valley. Distribution is strongly influenced by the nature of the crop at the beginning of the season, with clear preference for peanuts. However, at the beginning of the season, in October, it appears that the cranes select corn and peanuts equally, though this occurs only for a very short period of two weeks. As the season advances, distribution is no longer heavily dependent on the type of crop. According to an analysis, which we carried out, the fields selected by the cranes between December and the middle of March, were those that contained a high percentage of Cyperus rotundus.
The number of cranes drops significantly at the beginning of December but it can take place much later. Research shows that the dominant factors are the availability of peanuts, which is a function of rain that causes the peanuts to rot, and the quantity of peanuts in the field.
Fig. 12. Common Crane exemplars observed in the different agricultural fields during 1999.
Damage to agriculture
Cranes harm agriculture in two ways:
- Damage to fields sown in autumn (winter crops or autumn-sown perennials, e.g. alfalfa)
- Damage to fields prepared for sowing in late winter or spring.
Damage to sown fields appears in those preferred by the cranes, i.e., peanuts or those that are rich in reeds. The cranes leave some of the peanut fields very soon if they find no food in them apart from peanuts, and hence cause no damage, as long as these fields are sown after the visit of the cranes and harvest of the peanuts. It has also been found that fields sown with quick-growing crops (especially wheat) are not visited again by the cranes. However, during the entire period of research there were fields particularly rich in Cyperus rotundus that attracted cranes in the second half of the season.
It was found that cranes eat during the early morning hours, and either rest or occupy themselves with drinking from the ditches, at which time they flock around a number of specific ditches, during the rest of the day. Their selection of fields for feeding takes place immediately they leave their rest-grounds, first thing in the morning. Towards evening, they tend to congregate in one or two fields, and fly to their rest-grounds from there later on.
Picture 14. Gray Cranes in cultivated fields in the Hula Valley
Framework for dealing with damage
- The clear selectivity that cranes show in choosing their feeding areas makes it possible to provide them with such areas for winter- feeding. They would have to contain the elements mentioned.
- Cranes tend to feed in more than one place, to avoid over-utilization. Hence, as many as possible areas should be provided.
- The fact that cranes have a fixed daily routine demands appropriate action. Since there are sown areas suitable for feeding between those provided for the purpose, the cranes must be prevented from landing on the former when they first leave their rest-grounds. This would make the cranes choose the areas intended for them. Such action requires co-ordination between farms, since if each acted as it thought fit, the damage would be multiplied.
- Research has shown that driving the cranes away during the day has the opposite of the desired effect, because it leaves the cranes hungry and causes them to look for food in every possible place. Hence it is important to prevent them landing early in the morning where they are unwanted, and during the rest of the day to concentrate on preventing landing, rather than driving them away altogether.
- The size of the feeding ground has to be sufficient for it to be attractive. Hence, in my estimation, an area of not less than 30 ha has to be set-aside for the purpose.
- The area designated as a feeding ground should be protected as far as possible from trippers, and farmers should not move about too close to them, to avoid frightening the cranes away.
- Such designated areas should be close to ditches, with access to the water. Water is a very important factor.
- Supplementary food is only required between January and March, when there is no natural feed in the area.
- Constant monitoring is required to keep track of the application of the plan and draw conclusions from its effects.
- Feeding areas for the following year should be planned ahead, to avoid last-minute decisions.
- Overall, management is very important, in which times of sowing and harvest are both taken into account.
- The management plan should be mapped during each summer. Such a plan was implemented for winter 1999-2000.
Implementation of the framework in winters 1999-2000 and 2000-2001
The operative plan to reduce the damage caused by this bird in the Hula Valley during these winters consisted of three main elements:
- Preventing cranes settling on land designated as vulnerable to damage;
- Creating conditions for the cranes that will attract them to areas that are not vulnerable to damage;
- Monitoring effects in order to provide data for future conclusions.
1. The prevention of cranes settling on land designated as vulnerable to damage
Action has been taken by farmers, backed by a special team. The owners of the land designated as vulnerable oversaw these fields before the cranes settled and not afterwards. The accompanying team coordinated with the owners to make sure that there are no gaps left open. The accompanying team went go to the area to check the potential for damage, which is a function of the state of the soil and the presence of food utilized by the cranes in the specific field.
2. Creating conditions suitable for the crane that will attract them to areas that are not vulnerable to damage
Treatment of fields: Many areas which are not vulnerable to damage were marked on the map of the Hula Valley, especially fields which were not in use during the winter. These areas provided the alternative to sown fields. A number of conditions were ensured for these areas:
- Closure to visitors and workers, to prevent the cranes being driven away from these field, by means of explanatory signs, closure of paths and handouts to visitors and farmers.
- A part of the area was disked or cultivated, to increase its attractiveness.
3. Monitoring effects in order to provide data for future conclusions.
The accompanying team monitored actions and their effects, receiving professional advice from Dan Alon. This included counting the birds, monitoring the changes in their feeding grounds and calculating the efficacy of steps taken to minimize damage.
Results
After three day of driving away the cranes from the fields and preventing them from landing, no cranes were observed eating in the fields and all the flock were observed sleeping in the Hula Nature Reserve. Next, the feeding field containing corn and peanuts that were chosen as the alternative to fields were “opened” and the cranes were allowed to land and eat in them. The cranes adapted to this new situation and immediately start to visit these fields. At this stage the owners of the vulnerable field sill monitored the cranes each morning to prevent them from landing in their fields. After few more days the owner of the fields returned to their routine and only few rangers monitored the cranes. As a conclusion, the winter 1999-2000 is an example of how cooperation between fields owner and the ISPN and National Park Authority can prevent damage from cranes to agriculture whiteout harming the cranes and still encouraging them to continue migrating through the Hula Valley and stopping to “refuel” in the Agmon Lake area
V.6.2. Pelicans in the Hula Valley
Pelicans (Pelecanus onocrotalus) cross Israel in spring and autumn, stay a few days to eat high energy food, necessary to fill their reserves, and continue their journey north or south, according to the season. During their stay, they cause a lot of damage to the artificial fish ponds, mainly by eating fish, but also they are vectors to parasites, therefore the fisherman usually shoot and kill some of them (illegally).
Picture 15. Pelicans (Pelecanus onocrotalus)
Until 1994 the pelicans in the Hula Valley stayed in the Hula Nature Reserve, but after the partial re-flooding of the valley and the formation of Agmon Lake a reduction of the pelicans in the Reserve was observed. In the framework of the LIFE Project a comprehensive survey of birds in the area was conducted and the results show that the missing birds transferred to Agmon Lake (Fig. 13). One of the reasons is the dropping of surplus fish from the fish breeding ponds in Agmon Lake. This new resource of food attracts pelicans, prevents damage to the fishponds and attracts tourist that observe the “show” of pelican fishing. During 1999 and 2000, as a result of cooperative work between the Life team and the fisherman, the intensity of the conflicts decreased and no pelicans were killed in the Hula Valley fields.
Fig. 13: Amount of "pelican days" in the Hula Valley*
*"Pelican days" means the number of pelicans observed each morning between August and November, times the number of days of observation in the Nature Reserve.
V.6.3. Biological Control of vole population by lateral move irrigation system.
Medicago sativa (alfalfa), a species sensitive to voles, was irrigated by overhead sprinklers. Systematic observations were made in the irrigated area, showing that during the operation voles exit the soil and are predated by birds standing on the irrigation equipment.
Picture 16. Biological control of voles
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), Bubulcus Ibis, Cattle Egret/Buff-Backed Heron, Black Kite (Milvus migrans).
