Eur J Wildl Res (2005) 51: 199–206 DOI 10.1007/s10344-005-0092-1
O R I GI N A L P A P E R
Thierry Bonaudo Æ Yvonnick Le Pendu Jean Franc¸ois Faure Æ Darcisio Quanz
The effects of deforestation on wildlife along the transamazon highway
Received: 23 November 2004 / Accepted: 22 March 2005 / Published online: 10 May 2005 Springer-Verlag 2005
Abstract Hunting, although prohibited, is widely practiced by the rural inhabitants settled along the Transamazon highway. In 1997 and 2000, we investigated subsistence hunting in Uruara´, a township located on an Amazonian pioneer front (Brazil). We analyze hunting practices, game yield, hunting efficiency and their relation to forest coverage rate. The hunting methods were stand hunting (55.5%) and beating (44.5%). Paca (Agouti paca), tatus (Dasypus novemcinctus and D. septemcinctus), and collared peccary (Pecari tajacu) were the most frequently hunted species, supplying 68% of the gross game weight. Beating was significantly more efficient than stand hunting (3 vs. 1.9 kg/hunter/h, Mann–Whitney U test, P=0.02). Hunting territories were classified in three categories according to forest coverage rate. The higher the forest coverage rate the larger was the harvested species and the more efficient the hunter (Kruskal–Wallis test P=0.01). Considering the ecological and demographic changes in this pioneer
T. Bonaudo (&) De´partement TERA-Green, CIRAD, TA 60/15, 73 rue JF Breton, 34398 Montpellier Cedex 5, France E-mail:
[email protected] Tel.: +33-467-615966 Fax: +33-467-614415 Y. Le Pendu Universidade Estadual de Santa Cruz (UESC), Departamento de Cieˆncias Biolo´gicas, Rodovia Ilhe´us/Itabuna km 16, CEP: 45662-000 Salobrinho, Ilhe´us, Ba, Brazil E-mail:
[email protected] J. F. Faure Unite´ de Service ESPACE, IRD Centre IRD d’Orle´ans Technoparc, 5 rue du Carbone, 45072 Orle´ans Cedex 2, France D. Quanz Embrapa, CEP: 68 140-000 Uruara´, Para´, Brazil
settlement, development of a viable plan for game management and forest preservation is of great importance. Keywords Subsistence hunting Æ Amazon region Æ Game harvest Æ Pioneer settlement Æ Deforestation Æ Hunting techniques
Introduction In Brazil, vast colonization programs were started during the second half of the twentieth century with the settlement of thousand colons along axes of penetration called pioneers fronts. Anthropogenic degradation is more pronounced in border zones between wooded ecosystems and agricultural areas. Cattle ranching and lumbering are the main causes of both deforestation and the building of these new rural areas. The pasture would cover 80% of all deforested surfaces (Santana et al. 1997). The National Institute for Space Research suggests that from 1978 to 2000, 65 millions hectares of forest were lost in the Brazilian Amazonian region, i.e. more than the surface of Germany and Italy together (INPE 2003). Redford (1993) estimates that rural Amazonian populations in Brazil hunt 14 million mammals yearly. Peres (2000) increased the number to 23.5 million mammals killed every year. Under this circumstance, game meat consumption would be up to 89.224 tons representing a value of US$ 190 million per year (Peres 2000). In spite of its ecological, economic and food supply importance, fauna exploitation is not submitted to management or valorization. Even though legally forbidden, hunting is widely practiced. The majority of the rural population practices subsistence hunting. In fact, game is the most accessible source of animal protein. At the same time, hunting is a pastime maintaining social relations with neighbours. Consequently, it is necessary to put in place new ways of exploiting faunal
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resources while meeting local population needs and preserving Amazonian biodiversity. This study analyzes hunting practices on a pioneer front and tests the relation between game yield, hunting efficiency and forest cover. We also compare our results with those of a similar study conducted in the same region at the beginning of its colonization (Smith 1976) in order to detect any change in the hunting methods and game yield.
Fig. 1 Location of the study site
Methods Study Site The survey took place in the Uruara´ township (Para´, Brazil), 180 km west of Altamira on the Transamazon highway, between 0251 S¢ and 0416 S¢ and 5309 W¢ and 5417 W¢ (Fig. 1). Since 1970, this township has
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grown rapidly with the immigration of farmers coming from southern and northeastern regions, with a limited knowledge of the Amazonian environment. Actually, 13,000 urban and 32,000 rural inhabitants live on the 10.666 km2 of the township (IBGE 2000). Human density is low, about 4 inhabitants/km2, and is concentrated along the communication axes (Transamazon highway and trails). Farming is the main activity, with more than 6,500 rural households. More than 70% of the agricultural exploitations have an area of less than 150 ha (Veiga et al. 1996). Production is divided between annual (rice, cassava, corn, bean) and perennial crops (pepper, coffee, cacao), as well as extensive cattle ranching (Ferreira 2001; Toni 2003). Game meat is an important part of the diet for settlers who generally live in isolation. The average game meat consumption is 16.42 kg/individual/ year (Bonaudo et al. 2001). Lumbering is the second economic activity in the township and employs 1,500– 2,000 people. Anthropogenic degradation is still limited: in 1999, the forest ecosystem represented more than 85% of the surface of the township and the yearly deforestation rate was only 1% from 1992 to 1999 (Venturieri et al. 2003). The climate is equatorial, warm and humid with a rainy season from December to May and a mild dry season the rest of the year. Study period and hunters This study focuses on rural hunters, for whom game is an important nutritional part of their diet. We studied the practices of 40 hunters living along 15 trails. The surveys were conducted in two periods, from May 27th to September 29th of 1997 (127 days), and from April 28th to July 18th of 2000 (81 days). The surveys represented 133 and 94 hunting expeditions, respectively.
Data collection This study was completed successfully thanks to the collaboration of Embrapa Amazoˆnia Oriental agents and rural development technicians having the trust of the population. This allowed us to accompany them and present this research to the communities. We worked with the most interested colons. The first hunters who joined the project led other hunters to collaborate. The fact that one of the scientists (T.B.) lived in the township during several months prior to the study and knew the hard realities of pioneers’ life also facilitated to build relations of trust. Three methods were used to study hunting practices: 1. Interviews: hunters were questioned about their practices, i.e. hunting methods, hunting frequency according to season, harvested game species and locations.
2. Reports: hunters filled out activity report sheets every time they hunted, even when hunting was not successful. A hunt was considered successful when at least one animal was killed. A scientist (T.B.) visited each hunter weekly in order to help him fill out the hunting activity report sheets. 3. Direct observations: The same scientist accompanied each hunter, two to three times to validate the data collected during the interview. These methods allowed collecting individual data on methods, frequencies and duration of hunting, as well as the number of participants and the game yield. Consumed game species were allocated to three groups according to body weight. ‘‘Small’’ species weigh less than 10 kg: armadillo, Dasypus novemcinctus and D. septemcinctus; paca, Agouti paca; Brazilian agouti, Dasyprocta leporina; marail guan, Penelope marail. ‘‘Medium-size’’ species weigh from 10 kg to 20 kg: collared peccary, Pecari tajacu and gray brocket deer, Mazama gouazoupira. ‘‘Large’’ species weigh more than 20 kg: white-lipped peccary, Tayassu pecari; red brocket deer, M. americana; capybara, Hydrochaeris hydrochaeris. Jaguar (Panthera onca), margay cat (Leopardus wiedii) and coati (Nasua nasua) were also hunted but not consumed. Game gross weight for each consumed species was estimated by multiplying the number of animals killed by the mean gross weight of the species. The values used were provided by Fonseca et al. (1996) for mammals and Thery et al. (1992) for guan marail. Hunter efficiency was defined as the mean gross weight of consumed game harvested by a hunter during an hour. Values were compared according to hunting method (non parametric Mann–Whitney U test) and to forest recovery rate of the hunting territory (non parametric Kruskall–Wallis test and Dunn’s Multiple Comparisons test).
Hunting territory Each hunter had two to five favorite hunting locations situated at a distance of 0–20 km from their house. However, more than 95% of the hunting is carried out on foot, at a maximum range of 5 km from the house. Therefore, each hunting territory was defined as a disk of 10 km in diameter centered on the house of the hunter. The forest coverage rate of each individual hunting territory was calculated from a 1999 satellite picture (Landsat ETM+ scene). After correction, the channels 3, 4 and 5 of the picture were organized by automatic algorithms, according to a semi-supervised method elaborated from fit together masks (ERDAS Imagine software). Knowledge of the study site and the analysis of the satellite picture helped us to isolate main structures like water bodies, vegetation, roads, and bare soils. Then,
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those structural entities were divided in subtypes corresponding to different ecosystems: forest, fallows, pastures, etc. Forest recovery rate of each hunting territory was determined by superimposing the disks on the transformed image. These rates were then allocated to one of the three following types of habitat: Type 1: 49–65% of forest (n=8 territories) Type 2: 66–85% of forest (n=19) Type 3: more than 86% of forest (n=10).
Results Hunting methods Beating and stand hunting are the two methods used locally. A hunter chooses the technique according to his preference and the opportunity to have dogs. The search for a specific kind of game and the ecological characteristics of the hunting location do not influence his choice. Beating is done by one to six individuals with their dogs (1–12) and is carried out throughout the year. It begins at dawn and ends at noon, so that dogs can use fresh tracks on the trails. Beatings represent 44.5% (101/227) of all hunting. Peccaries, felines and coatis are killed exclusively during beatings. Hunting of brocket deer is mainly done by beating but deer are occasionally killed during stand hunting (Table1). Beating represents only 11% (n=5) of hunts conducted in hunting territories of type 1 but is preferentially practiced in more forested hunting territories (50 and 55% of hunts in hunting territories of type 2 and 3, respectively). Stand hunting is practiced alone, generally at night during the dry season. The hunter hides and waits at the bottom of a tree producing fruits that are sought by game. This method represents 55.5% of all hunting (126/ 227). Armadillos and pacas are mainly killed during stand hunting at night (respectively 63 and 79%, Table 1). This method is mainly practiced in low forested hunting territories, representing 89% (n=41) of the hunts conducted in hunting territories of type 1. Therefore forest recovery rate seems to influence the choice of hunting method. Hunters use 0.16 to 0.36-caliber rifles and home-made ammunition. Hunting methods and tools are rudimentary. Duration and frequency of hunts Hunting duration is highly variable, from 30 min to 12 h. Mean hunt duration is 3 h and 47 min (n=185 hunts of known duration) and does not differ according to the method used (Mann–Whitney U test, P=0.38) or among habitat types (Kruskall–Wallis test, P=0.78).
According to the interviews, hunters go hunting on an average 3.6 times a month during the dry season and only once every 2 months during the rainy season (annual mean=2). During our survey, hunters went out on an average of 2.3 times a month (SD=1.8, min=0 and max=7.7 hunt/month). Only three hunters did not shoot during our study period.
Hunted species Pacas and armadillos represent 61% of the animals killed, with 81 and 46 individuals, respectively (Table 1). Collared peccaries and red brocket deer are also frequently hunted. Transformed to gross weight values (Table 1), the same game species come first with paca (664 kg, 26%) followed by armadillo (570 kg, 22%) and collared peccary (522 kg, 20%).
Game yield A mean number of 0.92 animals are killed during a hunt, corresponding to a mean gross weight of 6.33 kg of game (n=227 hunts). Beating is significantly more efficient than stand hunting: 3.01 versus 1.91 kg (Mann– Whitney U test, P=0.02; Table 2). Game species differ according to the technique used: medium and large species like deer and peccaries are mainly hunted during beating whereas small species like pacas and armadillos are killed during stand hunting. The percentage of successful hunts is high in all types of habitat: 65, 63.9 and 69.7% respectively in types 1, 2 and 3. Yet, hunter efficiency varies according to the type of habitat (Kruskall–Wallis test, P=0.01; Table 3): it is significantly higher in type 3 than in type 1 (2.84 vs. 1.53 kg/hunter/hour, Dunn’s Multiple Comparisons Test, P
