Transcript Document
HABITAT SELECTION OF THE IBERIAN HARE (Lepus granatensis) IN A PLAIN AGRO ENVIRONMENT DEPENDING ON THE TIME OF THE YEAR.
BARTOLOMÉ, DANIEL J.; ALONSO, MARTA E.; PÉREZ, JOSÉ A.; DÍEZ, CARLOS; OLMEDO, JUAN A.
Dpto. Animal Production II. Fac. Veterinary, University of León. 24071. Spain.
E.mail: [email protected]
II WORLD LAGOMORPH CONFERENCE (VAIRAO, PORTUGAL) INTRODUCTION
The Iberian hare is a strictly crepuscular and nocturnal species (RODRIGUEZ, 1997). During the day it remains hidden in a small whole in the ground that it makes, called den (Photo 1). In Spain, few scientific studies have analyzed the location of these dens in different types of habitats during varying times of the year.
In view of the exigency of administration of the cynegetic resources, through the Plans of Cynegetic Organization, it is urgent the realization of studies of populations and the relation species-environment, on Iberian hares, which, without a doubt, is the least studied species within the Spanish small game.
MATERIAL AND METHODS.
1. STUDY AREA.
The realization of the study was carried out in the farm Coto Bajo of Matallana, property of the Most Excellent Country Council of Valladolid, located in the district of Villalba de los Alcores, in the North extreme of the province of Valladolid, Spain (41º 53’ 45”-41º 55’ 15” N latitude and 4º 51’ 10”-4º 52’ 50” W longitude); with a total extension of 300,70 has. which has a cynegetic fence built around. The farm lacks cynegetic exploitation.
Inside the farm, we find six different areas potentially usable by the hares. These areas can be grouped under the following names: -Reforested land (185,1 Has.): brooms, brambles and pines afforestation (Photo 2).
-Ploughed land (51,7 Has.), (Photo 3).
-Stubble (28,8 Has.): cereal lands that have been cut (Photo 4).
-Uncultivated land (1,6 Has.): abandoned crop lands (Photo 5).
-Alfalfa (24,1 Has.): formed by different smallholdings of alfalfa (Photo 6).
-Pastures (9,4 Has.): areas occupied by very dense and riverside herbaceous vegetation (Photo 7).
Photo 2: Reforested land Photo 3: Ploughed land Photo 4: Stubble Photo 5: Uncultivated land Photo 6: Alfalfa Photo 7: Pasture
2. ANIMALS USED.
With regard to the animals, a total of 19 hares were captured, all of them in the farm, therefore autochthonous. As regards age of the hares, 9 young animals and 10 adult ones were used. The sex proportion was 9 females and 10 males. All the captures were done at night. Each hare was located with the help of a jeep and a hand spotlight. Later, the animal was guided to the place where a net of nylon had been placed the afternoon before. Once there, the animal was captured and the corresponding radio-transmitter was fixed as a collar to its neck.
After determining the sex and approximate age of the hare, and identifying it by means of a numbered metallic crotal placed in one of its ears, the animal was immediately liberated (Photo 8). After this, a weekly and individualized study of the animals was realized by means of the radio-tracking system, previously used with hares by others authors such as RICCI in 1983 and RODRIGUEZ et al. in 1997.
Finally, each hare had its own file card where it was noted the habitat in which the animal was located in a map of the farm (scale 1:10.000).
Photo 1: Iberian hare resting in their den, over ploughed land.
Photo 8. Iberian hare with radio transmitter fixed to its neck.
3. PROCESSING OF THE DATA.
We used the Jacobs’s index for the analysis of the distribution of the diurnal dens in the different habitats of the farm throughout the year. Its value ranges between +1 and –1, and it allows to know the relative preference for a specific type of habitat by means of the following formula,
P x
x
1
x
1 / /
y
1
y
1
x
2 /
x
2 /
y
2
y
2
where: x 1 = number of dens located in the habitat x; x 2 = area of the habitat x in the farm; y 1 = total number of the studied dens; y 2 farm (300,7 has.) = total area of the Between 0 and +1, positive selection; 0, indifferent selection; and between 0 and –1, negative selection.
RESULTS AND DISCUSSION
The diurnal radiotracking of the marked hares allowed us to discover the spatial distribution of the dens in a whole year. Graphic 1 shows the values of the Jacobs’s index obtained for each type of habitat.
1,5 1 0,5 0 -0,5
Ja nu ar y Fe br ua ry M ar ch
-1 -1,5
A pr il M ay
Reforested land Stubble Pasture
Ju ne Ju ly A ug us t S ep te m be r O ct ob er N ov em be r D ec em be r
Alfalfa Uncultivated land Ploughed land
Reforested lands show positive selection, although scarce, during winter months and April, the rest of the year is negatively selected (more accentuated during the summer). Alfalfa presents positive selection when it is not cut, the rest of the year is negatively selected.
As far as stubble is concerned, it is very positively selected in August, but we have to take into account that it is only available during summer months, after the harvest. Uncultivated lands is the area that presents the highest rate of positive selection throughout the annual cycle except in January, February and July. Pastures is very positively selected at the end of the spring (May and June). Ploughed lands have positive selection during autumn months, when they have just been plowed and there is not much vegetation. As the agricultural year goes by, its selection becomes negative or indifferent.
In general terms, we find out that autochthonous hares present a higher preference for the uncultivated lands and pastures, which are, by the way, the ones that present less area. These two types of habitat are not subjected to the works of preparation of the land, sowing of the seeds, or harvesting, therefore they offer more tranquility to the hares during the day.
The variations of the index of preference are related to the diversity of the habitat. This diversity is given by the number and area of the smallholdings, and the homogeneous distribution of the uncultivated lands, which are not altered by agricultural works. In this way, the diversity of the habitat offers to the hare populations a wide range of places to locate their diurnal dens depending on the time of the year (RICCI, 1983).
Our results referring to the distribution of the diurnal dens differ substantially from the ones given by other authors. Thus, the method FRYLESTAM (1980) asserts that the habitats of feeding (nocturnal) more selected from February to April are alfalfa smallholdings and pastures.
However, in this study, the same habitats are negatively selected by the hares to establish their diurnal dens. These results, as CALZADA (1994) pointed out, would demonstrate that the hares do not live during the day in the same places where they feed at night.
BIBLIOGRAPHY
CALZADA, E.; MARTÍNEZ, F.J. (1994). Requerimientos y selección de hábitat de la liebre ibérica (Lepus granatensis) en un paisaje agrícola mesetario. Ecología, 8: 381-394. FRYLESTAM, B. (1980).
Utilization of farmalands habitats by european hares (Lepus europaeus) in Southern Sweden.
Viltrevy, 6, 271-284. RICCI, J.C. (1983). Suivi d´un lácher de lièvres d`importation (Lepus europeus)
au moyen de la radiotélémétrie: mortalité, dispersion et utilisation de lèspace. Acta Ecologica, 4,nº1, p.31-46. RODRÍGUEZ, M.; PALACIOS, J.; MARTÍN, J. A. (1997). La liebre. Ediciones Mundiprensa. Barcelona.