Yifat &
Crane
Eurasian cranes (Grus grus) in the
Hula Valley, Israel (Photos by Zadok
Machiev (left) and Amir Aloni (right))
Project description (Yifat
Davidson's M.Sc.'s Abstract): Examination
of crane-agriculture
management model in the Hula Valley
In the beginning of the 90's the Hula Valley
underwent many changes, as a part of a project for water and soil management rehabilitation:
many water canals were dug, a small lake was created and many new crops were
introduced to the valley. All of this and especially the introduction of
peanuts brought about a drastic increase in the wintering crane (Grus grus)
population in the valley. In order to deal with the large scale crop damage
caused by the cranes, the crane project was established in 1999. The project, incorporates agricultural and environmental
organizations, aimed at preventing crane damage along with protection of the
population. The management includes protection of the fields against the cranes
by variety of tools, expulsion of the crane population at the end of the fall
and feeding wintering cranes with corn in a feeding station.
Management for preventing wild life
damage, specially those using feeding stations, might have a negative impact on
the population ecology, such as behavioral changes, alteration of ecological
characteristics, disruption of life cycles (migration, wintering and nesting
periods) and physiological problems. The research which was conducted in the Hula Valley
in the winters of 2002-2004 was intended to deal with the following questions:
- Does the management have multi-seasonal impact on
the wintering crane population regarding population size, behavior, (habitat
selection and time budget) and demographic characteristics?
- What is the effect of the management on the number
of cranes, percentage of returning ringed cranes, habitat selection, time
budget and presence of other avian species in the valley?
- What are the nutritional and energetic
characteristics of the Euro-Asian crane in the winter?
- How can the management be improved and made more
efficient?
- What is the effect of tourism on the crane
population?
Study of the characteristics of the crane
population and their comparison with those in the years 1996-1999 (based on Dan
Alon's study) found that:
1. Monthly crane numbers increased since the beginning
of the crane project, although not significantly. The trend of change in the
crane numbers also changed – instead of a gradual departure from the valley as
of the end of January the population increased and the departure to the north
took place only at the end of February. These changes in the population size
result from the operation of the feeding station in the valley, which cause the
wintering and passing cranes to stay longer. An increase in the availability of
food in the valley caused a shift in wintering sites northward,
and hence the shortening of the migration route. This trend is reinforced by
the crane project and the feeding station: if the feeding station continues to
operate in the present format (100 days) a year, the danger will be that an
undesirable large wintering population will establish a winter base.
2. Habitat selection in the years of the crane project
operation is dictated by the level of field protection rather than by the type
of crop. This proves the efficiency of the field protection.
3. More breeding adult cranes and more small families
(with just one offspring) where observed during the years of the project. It is
not known whether this change in demographic characteristics reflects the whole
crane population from this migration route or it is a local change, pertaining to the crane
population which chooses to stay in the valley.
Study of the efficiency of the different
management activities, and their impact on the crane population found that:
1. Human presence is most efficient in protecting the
fields, and can not be replaced by other devices (such as scar-crows or
fireworks); focused protection of seeded fields is more efficient in preventing
crop damage than an overall protection of the whole agricultural fields in the
valley.
2. The expulsion operation at the end of the fall
affects crane decision to leave the valley south (most of them leave at night)
and thus reduce crane population in the valley. The expulsion operation in
December 2003 took place at a time when the feeding station was already
operating, and consisted of drastic actions. This caused a change in the
population composition (evident through low return percentage of ringed crane)
and in the demographic characteristics that year.
3. The feeding station starts opening at the beginning
of December and precedes the 100
mm accumulated precipitation threshold (a threshold that
proved to affect the food availability in the valley,
and to cause departure of passing cranes, Alon 2001).
Therefore it eliminates the natural pressure that a reduction in food
availability has on cranes. Closing the feeding station late in the spring
causes the cranes to stay longer in the valley and therefore delays the
migration waves north. A few ideas were examined as a part of the effort to
improve the attraction of the feeding station for cranes and to make it more
efficient: digging a water canal in the feeding station reduced the number of
cranes in nearby agricultural fields; the allocation of an additional ground
area as a feeding station was not successful in increasing the number of cranes
that visited the station every day; Changing the time of the food distribution,
from night to early morning, reduced the number of seed-eating birds (pigeons,
ducks) which use the feeding station; distributing the food inside the soil
("seeding") instead of spreading it on the ground also reduced the
number of seed-eating birds in the feeding station.
4. The influence of tourism on cranes in the valley
has was studied: intensive presence of vehicles and visitors close to the lake
caused the crane to avoid that roosting site, and to prefer the roosting site
at the reserve; The presence of visitors inside the feeding station (in a
covered wagon harnessed to a tractor-"mobile hide") was a disturbance
only during after noon hours, when cranes gathered in the station to pre-roost.
Cranes also drew away from the northern part of the feeding station, at the
boarding site of the wagon.
In order to find out which type of food is
better for using in the feeding station- corn, barley or peanuts- the cranes'
daily food consumption and food preference were
checked in cages:
1. The cranes preferred peanuts and barley over corn,
there was no obvious preference between peanuts and barley.
2. The daily food consumption was 180 (±60) gr per crane. The daily energy consumption was 595 (±230)
Kcal per crane. Both values did not differ significantly between the 3 food
types. All three food types provide the daily energy requirement for the cranes
but lack nutrient component (macroelements and trace
elements) that are necessary for the crane winter diet. These components are
present in natural foods that are found in the agricultural fields such as the
rhizome of Nutsedge (Cyperus
rotundus) and other sources (vegetal and animal).
Therefore it is expected that, for any food type chosen for use in the feeding
station, cranes will exit the station to search for food that contains those
components that are missing in the main food source.
Project description (Naama
Linndeman's M.A.'s Abstract): Ecological
and economic aspects of the "Crane Project" in the Hula Valley
The Common Crane (Grus
grus) is a migratory
bird living in large flocks (up to some tens of thousands), which arrives in Israel
in autumn and winters in the region. Cranes cause heavy
agricultural damage while feeding on crops such as maize, peanuts, sunflowers,
peas and wheat. Damage was especially severe in the last decade in the Hula Valley
in the north of Israel. Two main reasons for the multitude of cranes
in the Hula Valley were identified: (a)
re-flooding of an area of approximately 1,000 dunam
in 1993 creating a shallow lake (Hula Agmon) which is
used as a roost site and attracts large numbers of cranes and (b) modification
of the agricultural cultivars, mainly increase of areas of groundnut which is a
preferable food for cranes.
In the
last 5 years a “Crane Project” has been conducted in the area, aimed at
preventing the cranes damage to agriculture while maintaining the bird
population. The project is funded by the local farmers as well as supported by
public finance and donations. The main concept of the “Crane Project” is
regional cooperation between farmers, nature conservation activists and the
project implementers. The principals are guarding and eviction of the cranes to
prevent damage while correspondingly feeding them in a specially allocated
nearby area. To date, the economic profitability of this project has not been
examined.
This
examined the economic efficiency of this project as a public project aimed at
dealing with the farmers-cranes conflict while considering the Common crane as
a unique environmental resource. I checked cost and benefits of the project and
performed a general evaluation, while comparing three alternative management
methods used in the past and a new theoretical possible method. Out of the
previous methods, eviction was found most economically efficient. In addition,
I checked the farmers positions and their ability to
cooperate, as they are bearing the main burden. According to the results, the
main cost of the project (2/3) is funded privately by the Hula Valley
agriculturists – the main victims of the crane population, while the public
funding to the project is minor (1/3) and comes from the potential beneficiaries
of the crane population as an environmental
resource.
Despite
the aforesaid, the local farmers seem to support the project and give
precedence to the inferior economic alternative, by agreeing to the existence
of cranes in their vicinity. They are willing to cooperate and bear the costs,
as vast regional insight acknowledging the crane being a positive resource, on
top its being a pest.
The
study also checked the ecological and agricultural factors that influence the
crane dispersal and the project costs: available food amounts in the fields,
sowing time and characterizing and estimating the crane damages during the
research period. The results show that some of the farmer’s activities such as
guarding and tilling, affect the crane dispersal and the
available food quantities in the farmland. Guarding and crane eviction were
found as significant factors on the farmer’s costs and their willingness to
cooperate as well as on the crane dispersal in the area. The most effective
factors on crane dispersal in November and December are the type of the former
summer crops, and in December and January is the
guarding policy taken by the farmers. In the agricultural areas a 150-400%
surplus of food relatively to the estimated crane requirements was observed. In
December and January the amount of food wasn’t found as an influential factor
on their dispersal in the fields. In February and March, while reduction of
available food occurs, a significant positive correlation was found between the
amount of available peanut and nut grass (Cyperus
rotundus) and the crane numbers in the fields.
The
“Crane Project” is a rare opportunity for exploitation of the total benefit to
society, as an agricultural area combined with a unique birding site. The
research shows that since farmer’s policy and acts have the main effect on the
crane dispersal in the fields, there are actions to be executed to reduce the
farmer’s private cost and by that minimize the agriculture-cranes conflict. The
research also proves that by proper management it can be made sustainable and
beneficial for agriculturists and naturalists.