The impact of predators on livestock in the Abruzzo region of Italy

Rev. sci. tech. Off. int. Epiz., 1993,12 (1), 39-50
The impact of predators on livestock in the
Abruzzo region of Italy
R. FICO *, G. MOROSETTI ** and A. GIOVANNINI *
Summary: Free-living populations of wolves (Canis lupus Linnaeus, 1758) and
brown bears (Ursus arctos Linnaeus, 1758) regularly cause damage to livestock
in the Abruzzo region of Italy. The laws of the region provide for compensation
payments to owners for losses caused by predators.
In the present paper, 4,993 validated claims made between 1980 and 1988 are
examined.
Losses ascribed to wolf, bear and wild boar attacks were 92.1%, 7.8% and
0.1%, respectively, of the total losses caused by predators during this period.
The victims of wolf attacks were mostly sheep and goats (45.0%) and equids
(38.5%), followed by cattle (16.4%) and rabbits, fowl and dogs (0.2%). Bears
also principally attacked sheep and goats (67.6%), other targets being cattle
(18.5%), equids (9.5%) and bee-hives (4.4%). A significant difference was
observed between the number of attacks by wolves and bears, although both
populations are of similar size. Other statistically significant differences have
been observed between the periods in which the attacks take place on the
different livestock and the predator species which reportedly caused the
damage. Among cattle and equids, victims are mostly new-born or young
animals, while among sheep and goats only adult animals are attacked.
KEYWORDS: Brown bear - Damages - Italy - Livestock - Predation - Wolf.
INTRODUCTION
In the Italian regions where protected and endangered species such as wolves (Canis
lupus L i n n a e u s , 1758) and b r o w n b e a r s (Ursus arctos L i n n a e u s , 1758) are present,
compensation is paid by the authorities for the damage caused to livestock by these
animals. To date, there have been no specific studies on livestock predation in Italy. The
purpose of the present study is to quantify the phenomenon in the Abruzzo region and
to point out some behavioural differences between these two species of wild carnivore.
* Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Via Campo
Boario, 64100 Teramo, Italy.
** WHO/FAO Collaborating Centre, Laboratorio di Parassitologia, Istituto Superiore di Sanità,
Viale Regina Elena 299,00161 Rome, Italy.
40
THE STUDY AREA
2
T h e A b r u z z o region in central s o u t h e r n Italy has a total area of 10,741 k m . It
borders on the Adriatic Sea to the east and the Apennine mountains to the west, with
peaks reaching over 2,500 m. T h e region has two distinct climatic areas, and the
vegetation varies according to the altitude gradient and the corresponding climatic
differences (9,11). The region is divided into four provinces: Aquila, Teramo, Pescara
and Chieti (Table I). The numbers of domestic livestock from 1980 to 1988 (16,17,18,
19) are shown in Figure 1. T h e relative percentages of the three livestock categories
were as follows (mean values, 1980-1988):
- sheep/goats: 77.0%
- cattle:
19.3%
- equids:
3.7%.
TABLE I
Population
density and land use in the provinces of the Abruzzo region
(20,21)
(Italy)
Land use
Province Total area
km
Aquila
Teramo
Pescara
Chieti
2
5,034.46
1,948.27
1,224.67
2,558.67
P o
u l a
P «°
density
per km
2
59
145
241
149
n
Fields/plantations
Forests
r
km
2
3,243.32
1,377.97
953.34
1,964.18
2
(%)
km
(64.4%)
(70.7%)
(77.8%)
(75.9%)
1,503.38
307.91
150.38
287.03
(%)
Unproductive
areas
km
(%)
(29.8%)
(15.8%)
(12.3%)
(11.1%)
287.76 (5.8%)
262.39 (13.5%)
120.95 (9.9%)
335.49 (13.0%)
2
FIG.l
Livestock numbers in the Abruzzo region (Italy), 1980-1988
(16,17,18,19)
41
Livestock h u s b a n d r y m e t h o d s routinely a d o p t e d in the A b r u z z o region vary
considerably. Cattle and equids are generally left on semi-free p a s t u r e in the
mountainous areas from April to October. Foals are born mainly in April-May, while
the calving season is concentrated in May-June. Although p e r m a n e n t supervision of
herds is compulsory, this rule is often broken for economic reasons.
Sheep and goats are kept on pasture from June to October and are always guarded
by s h e p h e r d s and dogs. A t night, the animals are kept in roped-off enclosures. T h e
lambing season lasts all year long, with peaks in J a n u a r y - F e b r u a r y and S e p t e m b e r October, the latter period being the most important. L a m b s are usually slaughtered
within three to four months and, therefore, only adults are present in flocks in summer.
T h e A b r u z z o region is the only area in Italy w h e r e wolves and b e a r s are present
simultaneously. Wolves are mostly observed in the Parco Nazionale d'Abruzzo (Aquila
province) and on Mount Maiella (Chieti province). In 1976 (3), 1985 and 1986 (7), the
wolf population was estimated as 34-35, 62-77 and 59-79 individuals respectively. T h e
highest densities of brown bear and wolf populations are generally recorded in the same
areas. In 1974 (26), 1980 (13), 1985 and 1988 (6), the b r o w n b e a r p o p u l a t i o n was
estimated as 72,45-80,51-57 and 44-55 individuals respectively. National legislation has
been in force to protect the bear since 1939 (8) and the wolf since 1976 (3,5).
Only losses ascribed to the above two species are compensated for (in accordance
with Regional Law N o . 3/1974). T h e Provincial D e p a r t m e n t s of the State Forestry
Corps are responsible for the assessment and p a y m e n t of d a m a g e s . T h e r e is n o
compensation for damage ascribed to dogs. According to the 1980-1981 census, the
distribution of feral and stray dogs in the four provinces was as follows (4):
-
Aquila:
Pescara:
Chieti:
Teramo:
4,300
1,998
3,113
3,675
dogs
dogs
dogs
dogs.
MATERIALS AND METHODS
T h e d a t a analysed in this p a p e r concern claims for losses a t t r i b u t e d to wild
carnivores in these four provinces of the Abruzzo region from 1980 to 1988. Each claim
referred to only one validated attack.
D a t a w e r e collected on the n u m b e r , species and age class (if registered) of the
damaged domestic livestock and on the species of predator responsible for the attack.
The category "sheep/goats" includes all sheep and goats (male and female, adults and
young); "cattle" includes cows, bulls and calves; and "equids" covers mules, donkeys,
horses and foals.
T h e Spearman rank correlation was used to relate the n u m b e r of attacks on each
prey category with the number of head present in each category (25). The uniformity of
the m o n t h l y distribution for each prey category was e v a l u a t e d on the basis of t h e
Rayleigh test (1). The chi-square (X ) test was used to evaluate the difference between
the seasonal distributions of attacks (25).
2
Seasons were defined as follows: winter (January to March); spring (April to June);
summer (July to September); and autumn (October to December).
42
RESULTS
Claims for losses caused by wild carnivores from 1980 to 1988 totalled 4,993 in the
four provinces studied. Claims ascribed to wolf attacks numbered 4,600 (92.1%), while
389 attacks (7.8%) were ascribed to bears and 4 (0.1%) to wild boar. A t t a c k s w e r e
distributed between the four provinces as follows:
-
Aquila: 4,161
Teramo: 506
Chieti:
267
Pescara:
59
(83.3%)
(10.1%)
(5.3%)
(1.2%).
Wolf attacks
The largest number of attacks, 2,068 (45.0%), were against sheep and goats, while
1,769 (38.5%) were against equids, 755 (16.4%) against cattle and 8 (0.2%) against
other prey (fowl, rabbits, dogs).
The distribution by province of attacks attributed to wolves was as follows:
-
Aquila: 3,778
Teramo: 505
Chieti:
263
Pescara:
54
(82.1%)
(11.0%)
(5.7%)
(1.2%).
In the province of Aquila, where age classes of prey were r e c o r d e d , lambs w e r e
attacked in 0.8% of cases, calves in 96.4% and foals in 91.3%. Most attacks involved a
very low number of prey: in 50% of cases, the number of sheep/goats killed was less than
4 and in another 25% of cases the number of victims was between 4 and 7, while at least
75% of attacks against larger mammals involved only one animal (Table II).
TABLE II
Statistical analysis of numbers of animals killed in a single wolf attack on livestock
in the Abruzzo region (Italy)
Prey
Sheep/goats
Cattle
Equids
Min.
Max.
1
1
1
101
4
10
Number killed
Mean
Mode
5.95
1.09
1.10
1.0
1.0
1.0
Median
25
4.0
1.0
1.0
2.0
1.0
1.0
Percentiles
75
50
4.0
1.0
1.0
7.0
1.0
1.0
The claims regarding attacks on sheep and goats show an upward trend from 1981
onwards; those regarding equids show an increase from the same year, with a decrease
in 1987 and 1988. The claims referring to cattle remain relatively constant from 1982
(Fig. 2).
A positive and statistically significant correlation can b e observed b e t w e e n the
n u m b e r of wolf attacks on sheep and goats and the number of head of these species
present in the year considered (n = 9, r = 0.72, P < 0.05). F o r the other livestock
categories, the correlation was not significant (cattle: n = 9, r = - 0.42; equids: n = 9,
r = 0.63). A noticeable increase in wolf attacks on equids and cattle begins in April,
while the period of greatest losses among sheep and goats begins in July (Fig. 3).
s
s
s
300 -i
1980
1981
1982
1983
1984
1985
1986
1987
1988
Year
BB
Sheep and goats
Cattle
FIG.
I I
Equids
2
Annual frequency of attacks by wolves on livestock
in the Abruzzo region (Italy), 1980-1988
400
-i-
300 [-1
200 -
100-
I
LilnlHli
Jan
Feb
Mar
Apr
May
1! 11 1 111
Jun
Jul
Aug
Sep
Oct
Nov
Month
• i
C a
Sheep and goats
"le
Equids
FIG. 3
Monthly frequency of attacks by wolves on livestock
in the Abruzzo region (Italy)
Dec
44
The sample distribution parameters and results of the Rayleigh test are shown in
Table III. The peak of attacks on sheep and goats occurs in mid-August, the peak for
cattle is in mid-July, while attacks on horses occur mainly in late spring.
There is a significant difference between the seasonal distributions of attacks on the
three livestock categories. The following results were obtained in the chi-square test:
-
overall comparison:
equids vs cattle:
equids vs sheep/goats:
cattle vs sheep/goats:
2
X
X
X
%
2
2
2
= 433.07, P < 0.0001
= 85.07, P < 0.0001
= 426.86, P < 0.0001
= 56.32, P< 0.0001.
TABLE III
Distribution
Prey
Sheep/goats
during the year of predation by wolves on livestock
in the Abruzzo region (Italy)
Mean angle
in radians
3.852
(August 12) *
Angular
deviation
in radians
1.075
(62) **
Sample size
Significance
2,068
P < 0.001
Cattle
3.410
(July 17)
1.130
(66)
755
P < 0.001
Equids
2.553
(May 28)
1.100
(64)
1,763
P < 0.001
!
* date corresponding to mean angle
* number of days corresponding to angular deviation
Bear attacks
Claims for losses caused by bears concerned sheep and goats in 263 cases (67.6%),
cattle in 72 cases (18.5%) and equids in 37 cases (9.5%). In 17 cases (4.4%) the claim
concerned damage to bee-hives.
Bear attacks occurred in only three of the provinces studied and were distributed as
follows:
- Aquila: 380 (97.7%)
-Chieti:
5 (1.3%)
- Pescara:
4 (1.0%).
In the province of Aquila, t h e r e were no cases of b e a r s attacking lambs. Y o u n g
animals were involved in 90.3% and 77.7% of attacks on cattle and equids respectively.
As in the case of the wolf, most attacks by bears involved a very low number of prey:
in 50% of attacks on sheep and goats, only one or two animals w e r e killed, and in
another 25% of cases only three or four animals were involved, while at least 7 5 % of
attacks against larger mammals involved only one animal (Table IV).
There was a significant decrease in losses among all categories of livestock from 1981
to 1985. From 1985 onwards, an increase is registered (Fig. 4).
45
TABLE IV
Statistical
Prey
Sheep/goats
Cattle
Equids
analysis of numbers of animals killed in a single bear attack on livestock
in the Abruzzo region (Italy)
Min.
Max.
1
1
1
36
2
3
Number killed
Mean
Mode
2.5
1.0
1.0
1.0
1.0
1.0
Median
25
2.0
1.0
1.0
1.0
1.0
1.0
Percentiles
50
75
2.0
1.0
1.0
3.0
1.0
1.0
A negative correlation was found between the annual number of attacks on sheep
and goats and n u m b e r of h e a d p r e s e n t (n = 9, r = - 0.83, P < 0.01); t h e r e was no
significant correlation for other livestock categories (cattle: n = 9, r = 0.56; equids: n = 9,
r = -0.38).
s
s
s
Attacks on equids and cattle begin in April-May, while attacks on sheep and goats
are markedly higher in the period July-October (Fig. 5). The peak of attacks on sheep
and goats occurs in late A u g u s t , attacks on cattle p e a k in m i d - A u g u s t , while most
attacks on horses occur in mid-July (Table V).
Annual frequency of attacks by bears on livestock
in the Abruzzo region (Italy), 1980-1988
46
The seasonal distribution of attacks on equids differs significantly from the distribution
of attacks on cattle and sheep/goats. The chi-square test gave the following results:
-
2
overall comparison: x
equids vs sheep/goats: X
equids vs cattle:
X
cattle vs sheep/goats: x
2
2
2
= 28.26, P = 0.0001
= 25.19, P < 0.0001
= 10.29, P = 0.0001
=
3.62, P = 0.0001.
TABLE V
Distribution
of bear predation on livestock during the year
in the Abruzzo region (Italy)
Angular
deviation
in radians
Mean angle
in radians
Prey
Sheep/goats
Cattle
0.860
(51) **
0.860
(50)
0.940
(55)
4.056
(August 24) *
3.869
(August 13)
Equids
3.325
(July 12)
Sample size
Significance
263
P < 0.001
72
P < 0.001
37
P < 0.001
* date corresponding to mean angle
'* number of days corresponding to angular deviation
The seasonal distribution of attacks by wolves and bears on each prey category was
also compared. Wolves preyed on both sheep and goats (X = 28.87, P < 0.0001) and
cattle (X = 19.53, P = 0.0002) significantly earlier than bears, while no statistically
significant difference was noticed in predation on equids (X = 6.79, P = 0.0789).
2
2
2
70 -
ill
CO
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Month
• •
Sheep and goats
Cattle
FIG.
Equids
5
Monthly frequency of attacks by bears on livestock
in the Abruzzo region (Italy)
Dec
47
DISCUSSION
Given that wolf and bear populations in the Abruzzo region are of similar size, the
considerable difference in the overall number of attacks on livestock between the two
carnivore species can b e related to feeding habits. In fact, m e a t forms only a small
percentage of the diet of a bear (12,26).
However, the frequent difficulty in distinguishing between a wolf kill and a dog kill
may result in an overestimation of attacks by wolves.
Wolf attacks
There was a direct correlation between the number of wolf attacks on sheep and goats
and the number of these animals present on pastures. A similar observation was made by
Bogges and colleagues (2). The high percentage of attacks on equids (39.9%), despite the
fact that this category constitutes only 3.7% of the farmed livestock in the region, suggests
that wolf predation on equids is connected to breeding practices rather than to numerical
availability. In fact, n o significant correlation could b e found between the n u m b e r of
attacks and the number of equids present. Furthermore, a recent study carried out in the
Abruzzo region (23) showed that equids are one of the most common prey animals of the
wolf. T h e absence of a similar significant correlation for attacks on cattle could b e
explained by the fact that cattle exhibit more effective antipredatory behaviour (5) with the
result that, despite being more numerous than equids, cattle are preyed on to a lesser
extent. Predation on equids begins to be frequent in April, with a peak in May, because of
the availability of new-born and young foals on open pasture. In fact, the percentage of
young animals among the equids attacked is very high (91.3% ). Moreover, a typical feature
of the hunting behaviour of wolves is the selection of younger and weaker prey (22).
Attacks against cattle begin to be frequent in May, during the calving season. Attacks on
sheep and goats mainly occur in the summer months when flocks are pasturing. Lambs or
kids are rarely preyed upon, as they are sold very young. This study shows that wolves kill
large numbers of sheep more rarely than generally supposed: the n u m b e r of sheep
attacked in a single flock exceeded seven animals in less than 25% of cases.
Bear attacks
A comparison between the number of bear attacks on sheep and goats and the size of
the populations of these livestock species in a given year shows a significant inverse
correlation. Since the number of potential prey increased over the period considered in
this study, this result could be explained by a decrease in the bear population. In fact,
twenty-two bear carcasses were found between 1981 and 1984 (6) and attacks ascribed
to bears in 1985 were markedly low in number. The monthly distribution of bear attacks
significantly differs from the distribution for wolves. Since the same number of potential
prey is available to b o t h p r e d a t o r s , the difference in distribution may reflect t h e
seasonal p a t t e r n s of food-seeking activity among bears; Z u n i n o (26) describes this
activity as peaking in late spring (April-May) and early autumn (September-October).
CONCLUSIONS
From the data presented in this study, it appears that the impact of p r e d a t o r s on
livestock may b e linked to i n a d e q u a t e h u s b a n d r y m e t h o d s in t h o s e areas w h e r e
p r e d a t o r s are p r e s e n t . A similar o b s e r v a t i o n has also b e e n m a d e by R o b e l and
48
colleagues (24). The above data indicate that losses could be reduced by nearly 40% if
new-born or young foals and calves were not sent to graze o u t d o o r s . I m p r o v e d
surveillance of "at risk" herds (e.g. near large wooded areas and in areas with
confirmed, constant p r e d a t o r populations) would further decrease the n u m b e r of
attacks. F r o m this point of view, the problem of distinguishing b e t w e e n attacks by
wolves and those by stray or feral dogs is of no relevance. Moreover, field surveys in this
region are unable, at present, to confirm the hypothesis that feral dogs are responsible
for serious livestock losses (10,14,15). However, further studies are required in order to
clarify the ecological and ethological aspects of this problem.
ACKNOWLEDGEMENTS
T h e authors are indebted to Drs Q. D e Antoniis, B. Di Cesare, G. D i Croce,
P. Ranalli (Chief of the Ispettorati Ripartimentali del Corpo Forestale dello Stato in the
Abruzzo region) and the personnel of the Chamber of Commerce of Teramo Province,
without whose help the above research work would not have been possible. The authors
also wish to thank Drs F. Ambrosii and I. Capua for translating the text into English,
and Drs V. G u b e r t i and M. P a t a l a n o for giving their support in the discussion and
statistical analysis of the data.
* *
L'IMPACT DES PRÉDATEURS SUR LES ANIMAUX D'ÉLEVAGE DANS LA
RÉGION DES ABRUZZES EN ITALIE. - R. Fico, G. Morosetti et A. Giovannini.
Résumé : Les populations de loups (Canis lupus Linnaeus, 1758) et d'ours
bruns (Ursus arctos Linnaeus, 1758) vivant en liberté attaquent régulièrement
les animaux d'élevage dans la région des Abruzzes (Italie). La législation
régionale prévoit l'indemnisation des pertes dues à ces prédateurs.
Les auteurs ont étudié 4 993 demandes d'indemnisation acceptées entre 1980
et 1988.
Les pertes imputées à des attaques de loups, d'ours et de sangliers s'élevaient
respectivement à 92,1 %, 7,8 % et 0,1 % des pertes totales dues aux prédateurs
pendant cette période. Les victimes des attaques de loups étaient surtout les
ovins et les caprins (45,0 %), puis les équidés (38,5 %), les bovins (16,4 %) et
enfin les lapins, les volailles et les chiens (0,2 %). Les principales victimes des
ours étaient aussi les ovins et les caprins (67,6%), les autres cibles étant les
bovins (18,5 %), les équidés (9,5 %) et les ruches (4,4 %). Une différence
significative a été observée entre le nombre d'attaques respectivement imputées
aux loups et aux ours bien que ces populations soient de même taille. Les autres
différences statistiques observées ont concerné la période des attaques pour
chaque espèce attaquée parmi les animaux d'élevage et pour chaque espèce
jugée responsable. Parmi les bovins et les équidés, les victimes sont
principalement les nouveau-nés et les jeunes animaux tandis que chez les ovins
et les caprins, seuls les adultes sont attaqués.
MOTS-CLÉS : Animal d'élevage - Indemnisations - Italie - Loup - Ours
brun - Prédation.
49
IMPACTO DE LOS DEPREDADORES EN EL GANADO EN LA REGIÓN DE LOS
ABRUZOS EN ITALIA. - R. Fico, G. Morosetti y A. Giovannini.
Resumen: Las poblaciones de lobos (Canis lupus Linnaeus, 1758) y de osos
pardos (Ursus arctos Linnaeus, 1758) que viven en libertad atacan
regularmente el ganado en la región de los Abruzos (Italia). La legislación
regional prevé indemnizaciones por los daños que causan estos depredadores.
Los autores estudiaron 4.993 solicitudes
aceptadas entre 1980 y 1988.
de indemnización
que fueron
Las pérdidas por ataques de lobos, osos y jabalíes se elevaban,
respectivamente, a un 92,1%, 7,8% y 0,1% del total imputable a depredadores
durante el período. Las víctimas de los lobos eran sobre todo ovinos y caprinos
(45,0%), équidos (38,5%), bovinos (16,4%) y, por último, conejos, aves y
perros (0,2%). Las víctimas principales de los osos también eran los ovinos y
caprinos (67,6%), además de los bovinos (18,5%), los équidos (9,5%) y las
colmenas (4,4%). Se observó una diferencia significativa entre la cantidad de
ataques imputados a lobos y osos, pese a que las poblaciones
respectivas
cuenten con una cantidad similar de individuos. Las otras diferencias
estadísticas observadas se refieren al período de los ataques, en función de cada
depredador y de cada especie atacada. Las víctimas entre los bovinos y los
équidos son fundamentalmente los recién nacidos y los animales jóvenes pero
sólo los adultos ovinos y caprinos fueron atacados.
PALABRAS CLAVE: Depredación - Ganado - Indemnizaciones - Italia Lobo - Oso pardo.
*
* *
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