Corresponding authors: Nikolai Spassov (
Academic editor: Pavel Stoev
Data on the historical distribution of the golden jackal in Europe and its primary habitats are scarce. There are many new data on the population explosion and the rapid spread of the in Europe. However, the main factors for this expansion, the core population and its routes of dispersal, remain controversial or insufficiently studied.
This study provides a profound analysis of the history of the jackal’s (
Until recently, the golden jackal (
A total of about 700
Experimental fieldwork data, collected between 2014 and 2017 in Bulgaria, complemented the analysis of the factors limiting the spread of jackals’ populations in the country, as well as those which might be responsible for its expansion. The analysis of this case study was used as an explanation for the responsible factors for the whole continent. We collected data on jackal presence, aiming to relate the habitat characteristics variation with the positive answer proportion. To determine presence, we used a play-back bioacoustic method (
The area of distribution of the European subspecies
It possibly penetrated in the Early Holocene and lived as a rear animal without economic value for humans and has almost never been hunted (that is why it has not been found yet); as a good swimmer, it could penetrate from the east even in historical times (
The first record of a jackal in Europe (the south-eastern and eastern parts of the continent) dates back to the Middle Ages. The earliest reliable historical data are from the end of the 14thcentury (the vicinity of Sofia), from Turkish chronicles, during the siege of the town (
On the Adriatic coast, there were fragmented small subpopulations (apparently with temporary connections between them): from the Greek coast south of Ioannina to small spots along the Albanian coast and, from there, to the Dalmatian coastal area (including the Pelješac Peninsula and Korčula Island).
In Romania, the jackal was also an occasional visitor from Bulgaria, crossing the frozen Danube River during severe winters (
In Eastern Europe, the species occasionally penetrated from the Caucasus to the Don River estuary (
There are two very different tendencies of the population dynamics which are treated in this article as two periods: from the middle of the 20th century till the 1980s, a great reduction in the population was observed. It was followed by the beginning of a population expansion.
The core populations could be defined as follows: 1. Strandja coastal area of Bulgaria and Turkey (probably also some areas in E. Rhodope-Sakar Mts.) (
Most important in relation to the further expansion of the species are the first two core populations. The astonishingly high current number, over 30,000 individuals (
Bulgaria: In the late 1960s and early 1970s, after poison bait was banned and the protection of the species occurred (in 1962), the expansion began to the north (along the Bulgarian Black Sea coast) and to the west (in the Thracian lowlands and to the west of south Dobrudja) avoiding the high mountains (
Romania: In the early 1970s, the jackal reached Romanian Dobrudja again (
Serbia, Hungary and Slovakia: The species apparently spread westwards, reaching these countries through the lower Danube River plain, coming mainly from Bulgaria, but also from Romania. In the 1980s, the Romanian population expanded to the west and north, from where it reached again, in the early 1980s, Serbia (some individual records exist from the late 70s:
Republic of North Macedonia: In 1989, the species was registered in the north-western part of the country (
The combination of several factors (
In the 1980s, probably from the Dalmatian core population (
1. Natural ones: deep snow, extreme frosts, large forest massifs, heavily intersected (steep) relief and the presence of wolves. This last factor was discussed largely in the works of
2. Anthropogenic factors (strongly affecting the species existence in the first half of the 20th century): destruction of the habitats (scrublands and reeds) and direct destruction, mainly by poisoned bait (
1. Regarding
2. Concerning
3. Regarding
4. Additional factors with probable influence on jackal distribution (important also for wolves): we found that there were more positive answers in areas near water sources (< 1 km). However, it is important to note that, in this case, the positive answers were directly proportional to the sample size (Fig.
A unique combination of factors (mentioned below), caused by human activity in Europe, could also be responsible for the population explosion:
a. Deforestation;
b. Development of a network of roads;
c. Additional food sources, related to human activities: settlements with villages that producelarge amounts of food waste and agricultural activities;
The jackals prefer to be close to human settlements where there are scavenging opportunities (
d. Decrease of the wolf population (see the discussion above);
e. On the other hand, the simultaneous growth of the Balkan and Caucasian populations indicates that the expansion of those two distant populations could be a result of potential common factors such as climate changes and global warming. However, this hypothesis mostly applies to the recent penetration of the species into the most northern territories and is less applicable to the initial phase of population explosion, for example on the Balkans, which has happened in mild climatic conditions. The common reason for expansion should be related to the similar impact of the anthropogenic influence and the combination of the above-cited factors.
In addition, it should be considered that the jackal is extremely adaptive (
To synthesise, the exact chronology of the penetration of
The authors are grateful to the Programme “Young Scientist” of the Bulgarian Academy of Sciences for the research funding. Special thanks to the reviewers Dr. G. Giannatos, Dr. Georgi Markov and the anonymous one who provided valuable comments that helped to improve the manuscript. We also want to thank to I. Acosta, L. Alba, R. Babekova, O. Banea, N. Beltran, B. Grozdev, A. Ignatov, A. Klasanov, F. Regueros and M. Tonchev for their fieldwork assistance.
Geographic location of the calling stations (CS) during the bioacoustic survey. This map was created with QGIS 3.4.4 (QGIS Development Team, 2019).
Approximate distribution of the golden jackal in Europe from the end of the 19th until the 1930s of the 20thcentury. Based on data from
Approximate distribution of the golden jackal in Europe from the second half of the 1950s until the beginning of 1960s (the population minimum: see the text). This map was created with QGIS 3.4.4 (
Approximate distribution of the golden jackal in Europe at the beginning of the expansion: population explosion of the Strandja and the Adriatic core populations. This map was created with QGIS 3.4.4 (
Approximate distribution of the golden jackal in Europe from the end of the 20th until the beginning of the 21th century: continuance of the expansion. The basic contour of the distributions of the species (individual records incl.) are from
Proportion relationship between the jackals' positive answers and sample altitude (topography) as a factor that influences the jackal distribution.
Location of the jackals’ positive responses in relation to Bulgarian topography. This map was created with QGIS 3.4.4 (
Proportion relationship between the jackals' positive answers and sample vegetation type as a factor limiting the jackal distribution.
Proportion relationship between the jackals' positive answer and the sample regarding the wolf distribution (inside/outside wolf reproductive territory
Proportion relationship between the jackals' positive answer and the sample regarding the water source as a factor that influences the jackal distribution.
Proportion relationship between the jackals' positive answer and the sample regarding human settlements as a factor that influences the jackal distribution (population density; distance from the calling station < 1 km).
Proportion relationship between the jackals' positive answer and the sample regarding human settlements as a factor that influences the jackal distribution (population density; distance from the calling station between 1 and 3 km).
Proportion relationship between the jackals' positive answer and the sample regarding human settlements as a factor that influences the jackal distribution (population density; distance from the calling station > 3 km).
Proportion relationship between the jackals' positive answer and the sample regarding the anthropogenic activity as a factor that influences the jackal distribution.