Wydawnictwo
Uniwersytetu Przyrodniczego w Poznaniu

Głównym celem badań było wskazanie cech krajobrazu rolniczego, które warunkują intensywność jego zasiedlania przez sarnę, będącą pierwotnie gatunkiem lasów i lasostepów. Wzbogacenie wiedzy o funkcjonowaniu populacji saren na terenach rolniczych tym samym powinno umożliwić w przyszłości przygotowanie takich programów rolnośrodowiskowych, które ograniczając przyrodnicze zubożenie środowiska związane z intensyfikacją produkcji rolnej, będą sprzyjały zachowaniu tych zwierząt na możliwie dużym obszarze. Zaktualizowanie wiedzy o podstawowych parametrach populacyjnych dla saren polnych, co było składową badań, powinno z kolei pomóc osobom zarządzającym łowiectwem w opracowaniu strategii jej ochrony i użytkowania.

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1. WSTĘP 

2. CEL I ZAKRES PRACY

3. PRZEGLĄD PIŚMIENNICTWA 

4. MATERIAŁ I METODY 
4.1. Charakterystyka występowania saren polnych w krajobrazie rolniczym z wykorzystaniem telemetrii 
4.2. Ocena podstawowych parametrów charakteryzujących populację sarny polnej oraz struktury krajobrazu rolniczego na 10 terenach badawczych 
4.3. Zastosowane metody statystyczne 

5. WYNIKI
5.1. Wykorzystanie krajobrazu rolniczego przez sarny polne 
5.2. Podstawowe parametry charakteryzujące populację sarny polnej oraz struktura krajobrazu rolniczego na terenach badawczych 
5.3. Analiza zależności między parametrami populacji saren polnych a strukturą krajobrazu rolniczego

6. DYSKUSJA 

7. WNIOSKI 

ZAŁĄCZNIKI 

LITERATURA

SUMMARY 

The agricultural landscape in Poland is being profoundly transformed as a result of the intensification of agricultural production. Roe deer is one of just a few species, which have managed to adapt to dwell in the territories changed due to agricultural development in the 20th century. Unfortunately, in the 1990s a local decline in the number of the animals was observed due to unknown causes. The project, undertaken in 2009-2012, was intended to assess the interrelationships between the functioning of the field roe deer population and the landscape structure and exploitation of farmlands. A working hypothesis has proposed that the diversification of the density of field roe deer (and probably also other population parameters) is a result of changes in the structure of the agricultural landscape and the methods of farmland exploitation.

Material and methods
The habitat preferences of these animals were investigated during the period of two years (from December 2009 to December 2011) in one area near Czempiń (N 52◦08’N, E 16◦45’) in the Wielkopolska region using the radio telemetry method. Agricultural land dominated there by small midfield forests (of areas ranging from 10 to 285 ha) constituted only 9% of this territory. The area of 1600 ha, composed of three separate
unforested land plots each of ca. 500 ha, was chosen to carry out the research. The land areas featured typical elements of agricultural landscape structure, being large fields of agricultural enterprises (with crop fields ranging from 8 to 175 ha) and small fields of family farms (with crop fields ranging from 0.2 to 16 ha), and also clumps of trees and shrubs (of the areas ranging from 0.01 to 5 ha), tree belts (of width from 1 to 24 m), and urban areas (Table 1). The description of the habitat structure and the development of agricultural land in the study plots was provided for the growing season and winter period. Ten elements of agricultural landscape were distinguished for this purpose: winter cereals; spring cereals; maize; oilseed rape; alfalfa; root crops and other low spring crops; stubble fields and winter cover crops; ploughing; permanent  erbaceous plants (hayfields and pastures, as well as roadside verges and banks of ditches overgrown with spontaneous herbaceous vegetation sometimes with single trees or shrubs); clumps and belts of trees and shrubs (midfield clumps or wide belts of trees and shrubs, reeds, unfenced plantations of fruit trees or shrubs).
Field roe deer, including 7 males and 8 females, were caught in nets in the research area in autumn-winter period. They were from 1 to 4 years old. They were radio-collared with transmitters with activity sensors installed. The process of location of these roe deer in the course of which the type of habitat was determined, was carried out three times a week at different day times. Once a month multiple night and daytime observations were performed. 1093 locations in which the field roe deer stayed were described. They were used to characterise individual home ranges and to analyse habitat preferences (in the latter case 3% of occurrences of collared roe-deer were excluded as they were noted at the edges of small forests). A computer program Tracker applying the Minimum Convex Polygon method (MCP 95%) was used to characterise the individual home ranges of field roe deer. 47 daily, 31 seasonal and 9 annual home ranges were determined. Additionally, for each seasonal home range the share of large and small fields was estimated. Moreover, for each roe deer location, the distance was measured to the nearest forests and buildings. The habitat preferences of field roe deer was evaluated on the basis of x² test by comparing the frequency of usage of particular elements of agricultural landscape by collared individuals in contrast to expected frequencies – resulting from the share of such landscape variables in the research area.
Basic population parameters of field roe deer and the structure and exploitation of farmland were appraised once in 10 territories situated in several agricultural areas of western Poland (Fig. 1, Table 2) and differing in respect to the population density of these animals. The data enabling description of population parameters were collected from 1 October to 15 March, in the territories located over 200 m from forests. Such principles of information gathering favoured the restriction of observations to roe deer living in fields throughout the year (a part of forest roe deer individuals lives among fields in the summer, but they come back in autumn to their home range in forests and use only fields near forests as feeding grounds). The density and sex structure in particular populations were assessed at the end of February and beginning of March by applying the direct counting method in the whole field and combined with scaring away animals staying in small clusters of trees, shrubs or reeds. The reproduction rate was determined on the basis of registering roe deer observations in October and at the beginning of November, which enabled calculation of the average number of fawns per adult female from the autumn population. The data on the mortality of adult roe deer as a result of shooting were obtained by documenting the hunting bag of females. The culled female individuals at the same time provided information on the age structure and the body weight. To obtain the data, the roe deer were weighted (after removing internal organs from the body cavity) and their mandible were prepared. The age assessment was performed on the basis of histological specimens cut out from the back of the first molar (after decalcification) with a freezing microtome.
In each of the ten study areas in western Poland the agricultural landscape structure in winter was described. The data were collected in 30 kilometre long transects chosen at random. The proportion of chosen elements of agricultural landscape was calculated by dividing their total width ascertained in transects by the length of routes in a given terrain. Due to transects, the index of crop fields fragmentation and the index of asphalt road density expressed by a number of fields or roads for 10 kilometres of a route respectively were obtained. The occurrence of forests and urban areas was ascertained on the basis of cartographic maps of research areas in 1: 25 000 scale. The respective indices were calculated by dividing the number of squares of the area of 1 km2 (surface between the lines of a map graticule), in which either forests or buildings were present by the number of all squares, which were entirely within the borders of a given research area. The midfield forests are understood here as afforested areas of an area exceeding 10 ha. The indices of the availability of farmland were calculated in the same way, i.e. the number of squares in which there were no midfield forests, buildings and fenced area, e.g. orchards constituted a numerator. The variability of basic population parameters was subsequently analysed in relation to the existence of agricultural landscape elements, which were most pertinent to field roe deer with transmitters – the method used was multiple regression analysis.

Results and conclusions
The daily home ranges of field roe deer varied from 0.3 to 38.6 ha, while the largest ranges were observed in springtime (Table 3). The seasonal home ranges, in turn, varied typically from 14.5 to 81.7 ha. No significant differences were noted in the size of seasonal home ranges between roe deer living in large and small crop fields (Table 4). The area of annual home ranges of roe deer (which did not leave the territory of collaring) varied from 50.8 to 179.5 ha, on average 90.8 ha. The radio telemetry research confirmed the presence of roe deer, which throughout the whole year inhabited agricultural areas, entering edges of midfield small forests only occasionally. The locations of field roe deer on average were placed over 1.2 km from the forest edge and 0.8 km from buildings (Table 5).
The field roe deer used the distinguished elements of agricultural landscape selectively. The observed field roe deer population preferred clumps and belts of trees and shrubs in farmland (including orchards and fruit bushes), and oilseed rape fields, which served as both the activity and rest areas throughout the year (Tables 6, 7, 8). Maize, in turn, was the favourite place of activity and rest in the plant growing season, while cover crops and stubble fields played a similar role after the end of the growing season of cultivated crops. Alfalfa, as well as meadows, roadsides, ditches, and other areas with the permanent herbaceous flora were the preferred activity places in the vegetative season. Field roe deer
used definitely less than the territorial accessibility of the following types of crops: winter cereals, which were the most frequently occurring in the investigated part of Poland, as well as less frequently occurring spring cereals, root plants and other low spring plants. Habitat preferences of field roe deer were similar in large and small crop fields (Table 9). The population of field roe deer in western Poland was marked by a spring density at the level of 6.5 individuals per km2 (from 1.8 to 14.4 individuals per km2 in particular areas), with a majority of females – 1.57 females per male (Table 10). The fact that females dominated may have been a result of their lower mortality as a result of hunting, which on average amounted to 5% in comparison to the spring population (Table 12). The reproduction rate amounted to 0.47 fawns per female from the autumn population, and therefore the proportion of individuals in the first year of life amounted then to 24% of the whole population (Table 11). The average age of adult females was 4 years (Table 13). The body weight of adult females (after removing internal organs) was 17.2 kg on average, and differed between territories but did not change significantly in consecutive periods of life (Table 14).
The multiple regression analysis of dependencies between the population parameters and habitat variables has revealed that the density of field roe deer in western Poland has increased as a result of the rise in the proportion of open farmlands as well as oilseed rape fields (Table 17). Simultaneously it has been observed that an increase in clumps and belts of trees and shrubs in farmland led to the decrease in field roe deer density. It is shown that although the fields with clumps and belts of trees and shrubs were habitat elements preferred by field roe deer during the year, but a high level of them in some territories sometimes limited the density of the investigated populations. It was a consequence of the fact that those tree patches and shrub areas occurred normally in more wooded territories. Therefore, it provided more favourable conditions for seasonal (summer) dwelling of forest roe deer in agricultural areas, which may have led to the increase in inter-species competition in such territories.
In the light of the results, the reason for the locally observed decline in the population of field roe deer in Poland at the end of the 20th century and the beginning of 21st century was most probably the decreasing access to open farmland as a result of the fragmentation of such areas by new afforestations and land development for housing purposes. It was the consequence the statute that then numerous agricultural land areas with soil of the lowest quality class were afforested and the agricultural territories were progressively urbanised as a result of emigration of residents from major cities. Adverse changes observed locally in the Polish agricultural landscape should not, however, lead to the disappearance of the population of field roe deer because the increase in the share of cultivated crops favoured by them is conducive to their presence in many territories. Such favoured cultivations include oilseed rape and maize, used in the 21st century also as a raw material for bio-fuel production, while winter cover crops and grasslands are supported by agri-environmental programmes in the European Union.