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Impacto del turismo en la diversidad de aves, abundancia y composicin de la comunidad
Impact of tourism on bird diversity, abundance, and community composition
In recent years the ecotourism industry has been touted as offering incentives for protecting biodiversity while promoting economic growth for the surrounding communities. This paper examines the impact that ecotourism has on bird communities in the Monteverde Cloud Forest Preserve. Abundance and species richness for birds were compared on tourist trails and trails closed to tourist. The results indicated no significant difference in H values between trail types. The average species richness between trail types was not significantly different, but tourist trails significantly increased in average abundance. Increases
may be a result of food resources provided by the Preserve on tourist trails or to a decrease in predation on such trails. Sustainable tourism requires an awareness of the pitfalls of tourism and requires efforts to minimize the impact visitors have on the environment.
En los ltimos aos la industria del turismo se ha presentado como una solucin potencial para los problemas de conservacin, porque ofrece el estmulo para proteger la biodiversidad al promover crecimiento econmico para las comunidades circundantes. Este estudio examin el impacto que ese turismo tiene en comunidades de aves en la Reserva del Bosque Nuboso de Monteverde. La abundancia y la riqueza de especies para aves se compararon en los senderos de turistas y en los senderos cerrados al pblico. Los resultados no indicaron diferencias significativas en H' entre los diferentes tipos de sendero. La riqueza de especies promedio entre los tipos de sendero no fue significativamente diferente, pero la abundancia promedio entre los tipos de sendero fue significativamente diferente. Los aumentos pueden ser el resultado de recursos alimentarios ms abundantes de alimento proporcionados por la Reserva, o ser debidos a una disminucin en la depredacin en los senderos. El turismo sostenible requiere el conocimiento de las posibles trampas del turismo y requiere esfuerzos para aminorar el impacto que los visitantes puedan tener en el ambiente.
Text in English.
Monteverde Cloud Forest Reserve (Costa Rica)
Reserva Biolgica Bosque Nuboso Monteverde (Costa Rica)
Tropical Ecology Spring 2005
Ecologa Tropical Primavera 2005
t Monteverde Institute : Tropical Ecology
1 Impact of tourism on bird diversity, abundance, and community composition Micah Scholer Department of Biology, University of Minnesota ABSTRACT In recent years the ecotourism industry has been touted as offering incentives for protecting biodiversity while promoting economic growth for the surrounding communities. This paper examines the impact that ecotourism has on bird communities in the Monteverde Cloud Forest Preserve. Abundance and species richness for birds were compared on tourist trails and trails closed to tourist. The results indicated no was not significantly different, but tourist trails significantly increased in average abundance. Increases may be a result of food resources provided by the Preserve on tourist trails or to a decrease in predation on such trails. Sustainable tourism requires an awareness of the pitfalls of tourism and requires efforts to minimize the impact visitors have on the environment. RESUMEN En los Ãºltimos aÃ±os la industria del turismo se ha presentado como una soluciÃ³n potencial para los problemas de conservaciÃ³n, porque ofrece el estÃmulo para proteger la biodiversidad al promover crecimiento econÃ³mico par a las comunidades circundantes. Este estudio examinÃ³ el impacto que ese turismo tiene en comunidades de aves en la Reserva de Bosque Nuboso de Monteverde. La abundancia y la riqueza de especies para aves se compararon en senderos turistas y en senderos cer rados al pÃºblico. Los resultados no indicaron diferencias significativas en H' entre los diferentes tipos de sendero. La riqueza de especies promedio entre los tipos de sendero no fue significativamente diferente, pero la abundancia promedio entre los tip os de sendero fue significativamente diferente. Los aumentos pueden ser el resultado de recursos alimentarios mÃ¡s abundantes de alimento proporcionados por la Reserva, o ser debidos a una disminuciÃ³n en la depredaciÃ³n en los senderos. El turismo sostenible requiere el conocimiento de las posibles trampas del turismo y requiere esfuerzos para aminorar el impacto que los visitants puedan tener en el ambiente. INTRODUCTION Ecotourism provides benefits for local communities by creating jobs, supporting biodiv ersity conservation, and raising public awareness of environmental issues by exposing people to nature (Blamey 2001). The ecotourism industry in Costa Rica has grown immensely in the past decades and currently one of the largest grossing economic industry in Costa Rica (Rojas 2004). Between 2003 and 2004 the number of foreign tourists visiting Costa Rica increased 27%, totaling in excess of 3.2 million (Loloaiza 2004). Following this trend, the well known Monteverde Cloud Forest Preserve has seen a dramat ic increase from 25 thousand visitors in 1990 to over 73 thousand tourists in 2004 (Rodriguez pers. comm., Fig 1). However, ecotourism can negatively impact natural communities. Stresses induced by ecotourism can cause changes in population densities, com munity
2 composition, and the behavior of animals (Hindinger 1999). Beale and Monaghan (2004) demonstrated that bird communities in southeast Scotland perceive humans as potential predators. Their studies revealed that the hatching and fledging success of Kittiwakes, Rissa tridactyla , were significantly reduced when colonies were located in close proximity to tourist destinations. A study conducted in Tikal National Park, Guatemala, showed that animal populations responded differently following a sharp inc rease in ecotourism. Three mammal species experienced increases in their populations while three species of birds decreased in abundance (Hindinger 1999). Case studies conducted in Milford Sound, showed dolphin behaved differently when confronted with to urists. Populations were shown to both actively avoid boat interactions where as other species were more likely to travel after an interaction with a vessel (Leusea 2004). The avifauna of Monteverde has been widely studied, yet little quantitative data ex ists on the effects of human activity on bird populations (Young and McDonald 2000). Specifically, widening trails and creating new paths for ecotourism may encourage colonization birds that prefer disturbed habitats (Wheelwright 2000). Birds, such as th e Ochraceous Wren, Troglodytes ochraceus, Slate throated Redstart, Myioborus miniatus, and Golden browed Chlorophonia, Chlorophonia callophrys, readily colonize these disturbed habitats (Stiles and Skutch 1989). Additionally, the expanding ranges and incr easing densities of birds that respond positively to disturbed areas can potentially cause increased competition with other species for food (Wheelwright 2000). This study seeks to quantify changes in Monteverde Cloud Forest Preserve avifauna subjected to varying levels of ecotourism visitation by comparing bird diversity, abundance, and composition on trails frequented by tourists versus trails closed to the public. This research will provide an important case study on the effects of ecotourism and human activity on tropical avian communities. METHODS Data collection took place in the MVCFP between the dates of April 20 th and May 7 th using trails restricted to lower montane wet forest. An altimeter was used to insure that all data points fell within t he range of 1500 1600m. Trail types were classified as tourist trails (South El Camino and Sendero Bosque Nuboso) and those with restricted access (Closed Trail). Tourist trails were open to the public while closed trails were accessible by only a few re searchers. There was no noticeable difference in the age, species, or structural complexity of tourist versus closed trails. Six sample sites were located on each trail type approximately 200m apart. Sites one through six were located on tourist trails while sites seven through 12 were located on trails closed to the public. Sites seven and eight on the closed trails were within 100m of the tourist trails. Point counts were used to sample birds using a combination of auditory and visual identification. Nesting areas on trails were visually identified between sites. Nests were observed for activity each day to assure they were being used. Stiles and Skutch (1989) was used to aid in visual identification of birds while audio identifications were based on recordings of common Cloud Forest birds of Monteverde (Ross 1997). Birdcalls were only documented from a maximum distance of 50m. Point counts lasted 15 minutes in duration and were taken from 7:00AM to 10:00AM and again from 2:00PM to 5:00PM. The visi tation time of site numbers was alternated on a twelve day cycle to avoid
3 sampling bias due to the time of day (Table 1). Bird abundance was calculated with and without the presence of hummingbirds. Tourist trails offer a better vantage point for viewing birds. To insure that the number of birds identified on each trail type represents the actual number of birds found there the percent of identifications made by call was calculated for both communities. RESULTS Overall a total of 1963 individuals were identified belonging to 47 species. The tourist trails had a higher richness and abundance (S = 43, Smarg = 5.98, N =1119) than the closed trails (S = 36, Smarg = 5.19, N = 844). Chi squared values indicated no significant difference for richness ( x 2 = 0 .62, d.f. = 1) but found a significant difference for the abundance between trail types ( x 2 = 96.4, d.f. = 1). Bird abundance was not significantly affected by the presence of hummingbirds ( x 2 = 0.765, d.f. = 1). The percent of individuals identified by call for the tourist trail was not significantly different from closed trails (68% vs. 72%, x 2 = 0.114, d.f. = 1). The evenness for tourist trails (E = 0.763) was slightly lower than that of the closed trails (E = 0.807). No significant values were observed between the two trail types (t = 0.46, P < 0.05). The 12 sites varied in their average species richness both within and between trails types (Fig 2). The most substantial differences, however, occurred more between different trai l types than between trails of a single type (tourist vs. closed, Table 2). Although not significantly different (P = 0.785), the lowest average species rich site for tourist trails (8.000 +/ 1.128) was still greater than the highest average species rich site for closed trails (7.833 +/ 1.642). Similar trends were found for the average abundance for each site (Fig 3). The most substantial variations were found between, not within, trail type (Table 3). Though not significant (P = 0.0615), the lowes t average abundance for tourist sites (14.250 +/ 3.289) was greater than the highest average abundance for closed sites (12.000 +/ 2.174). Seven active nest sites were found on the tourist trails while no nests were found on the closed trail. The nests belonged to seven different species of birds including: Black faced Solitaire, Black Guan, Emerald Toucanet, Golden browed Chlorophonia, Grey throated Leaftosser, Resplendent Quetzal, and a Slate throated Redstart. Mating pairs from each of these specie s were observed tending nests on tourist trails. The most common birds (Appendix 1) seen in this study were usually observed everyday on four or five of the tourist sites. For example, the Common Bush Tanager was observed on a minimum of four tourist site s, ten out of12 days (n = 153). On the closed trails the Common Bush Tanager was identified on a maximum of four sites for only seven of the 12 days (n = 123). This suggests that tourist sites have a high degree of overlap in their species richness. There fore, there is a higher likelihood of observing more species of birds in a given observation period on the tourist trails (Fig 2). It was also more likely that more individuals of these species would be seen for a given observation period (Fig 3).
4 DISCUSSION Growing ecotourism in Costa Rica is putting increasing pressure on reserve systems to develop ways to accommodate more tourists while minimizing impact on local wildlife (Loloaiza 2004). This study expected to see that bird communities along h ighly trafficked trails would have a lower diversity and species richness than trails that were closed to the public. However, the results of this study did not support this hypothesis and indicated that the total diversity and species composition for eac h of these communities was very similar. One explanation for the increased abundance of bird species found on tourist trails is that food resources are more plentiful. The Monteverde Cloud Forest Preserve has incorporated different species of hummingbi rd pollinated and frugivorous bird dispersed plants including: Columnea lepidocaula, Psychotria elata, Cenropogon solanifolius, and Heliconia tortuosa (Rodriquez pers. comm.). The majority of these plants are located around the reserve buildings and restri pollinated plant species. The pollination garden is in close enough proximity to the observed study site that it may be acting as a species so urce, increasing the local abundance of birds on the surrounding trails. In addition, several Lauraceous trees had also been planted near the major trails tourist attracti on, the Resplendent Quetzal. Lauraceaeous fruits are rich in amino acids 2000). In the next 15 years the MVCFP plans on incorporating 3000 Lauraceous trees, which cou ld increase bird abundance in the future. Another reason for an increase in species abundance on tourist trails could be a result of fewer predators. Negative impacts on foraging and reproductive rates in Felids have been attributed to tourism (Hindinger 1999). In addition, long term studies of primates often report increases in population sizes due to decreased predation associated with the presence of researchers (Griffiths and Van Shaik 1993). Where human traffic is common, some animals become habitu ated to human presence (Griffiths and Van Shaik similar techniques to evade predation. B irds are especially susceptible to predation before they even have a chance to fly. Nest predation by mammals accounts for a substantial amount of mortality in bird species of Monteverde (Young and McDonald 2000). The presence of more nest sites may be a n indicator of fewer predators. On the tourist trail seven nests belonging to seven different species were identified within 25m of the trailhead (Table 2). Studies in Europe have shown that nest predation is reduced in human altered environments (Marhn and Clobert 1996). House Wrens in Monteverde showed a significant increase in nestling success when they nested in close proximity to humans (Winnet Murray 2000). However, direct observation of predators was not assessed in this study. Predation pressur e could be compared between trail types using artificial nests and quail eggs to reveal the degree to which ecotourism affects predator densities (Hartley and Hunter 1998).
5 One variable this study did not test was the relationship between trail width and species richness and abundance within bird communities. Generally, tourist trails were wider than closed trails. Major trailheads, such as South El Comino and Sendero Bosque Nuboso, had trail widths between two and three meters to accommodate guided tour groups (Rodriguez pers. comm.) Wider trails may increase temperature, available light, and evaporation associated with edge effects (Zartman 2003). These factors alter plant community composition, which could indirectly influence the species richness an d abundance of birds (Lovejoy et al. 1986). Although the closed trail sampled had very few visitations it was not completely free of human activity. Taking richness and abundance counts farther away from the Preserve would help insure that human activity was not affecting the bird communities found there. Bruce Young (2000) asserted that ecotourism directly effects just a few hundred of the 20,000 ha preserved in Monteverde, further adding that any negative effects felt by avian populations in areas un der the influence of tourism would be negligible with regard to the whole reserve system. However, this is a dangerous attitude to adopt from a conservation standpoint. Tourist activities may be altering predator prey interactions and changing the distri bution of seed dispersers (Hindinger 1999). Tourism can also made to understa nd the effects of tourism and how reserves can minimize the impact tourists have on the environment. LITERATURE CITED Beale, C. M. and P., Monaghan. 2004. Human disturbance: people as predation free predators? Journal of Applied Ecology. 41: 335. Blamey, R. K. 2001. Encyclopedia of Environmental Tourism. pp. 3. CAB International Press, Sydney, Australia Griffiths, M. and Van Schaik, C. P. 1993. The impact of human traffic on the abundance and activity periods of Sumatran rain forest wild life. Conservation Biology 7(3): 623 626. Groom, M. 2000. Patterns in the regeneration of Lauraceous trees in abandoned pastures. In: Monteverde: Ecology and Conservation of a Tropical Cloud Forest, N. M., Nadkarni and N. T. Wheelright, ed. Oxford Univers ity Press, Oxford, NY, pp. 442 443. Hartley, M. J. and M. L., Hunter. 1998. A meta analysis of forest cover, edge effect, and artificial nest predation. Conservation Biology. 12:456. Hindinger, L. A. 1999. Measuring the impacts of ecotourism on animal popu lations: a case study of the Tikal National Park, Guatemala. Yale F and E.S. Bulletin. pp. 49 57. Karlson, R. H., H. V. Cornell, and T. P. Hughes. 2004. Coral communities are regionally enriched along an oceanic biodiversity gradient. Nature. 429: 867 8 70. Loloaiza, V. 2004. El Pais Parques Nacionales Ayunos de Inuobesion. La Nacion. May 23. 6A. Lovejoy , T. E., Bierregaard, R. O., Rylands, A. B., Malcolm, J. R., Quintela, C. E., Harper, L. H., Brown, K. S., Powell, G. V. N., Schubart, H. O. R., and M. B . Hays. 1986. Edge and other affects of isolation on Amazon forest fragments. In: Soule, M. E. (Ed). Conservation Biology: the science of scarcity and diversity, pp. 257 285. Sinauer Associates: Sunderland, Massachusetts. Lusseau, D., 2004. The hidden cost of tourism: detecting long term effects of tourism
6 using behavioral information. Ecology and Society. 9: 1 9. Marhn, T., andJ., Clobert. 1996. Nest predation and avian life histroy: evolution in Europe versus North America, a possible role of humans. Ev olutionary Biology. 147: 1028 1046. Rojas, J. E. 2004 Economia se Despara Ingreso de Tourismo por Aeroeuertpos. La Nacion. July 26. pp. 2. Ross, D. L., Jr. K. N. Rabenold, and T. R., Simons. 1997. Indicator Birds of the Costa Rican Cloud Forest. Library of Natural Sounds, Ithaca, NY. Stiles, G. F., and A. F. Stiles. 1989. A Guide To The Birds of Costa Rica. Plates 12 50. Brodock Press Inc., Utica, New York. Wheelright, N. T. 2000. Conservation Biology. In: Monteverde:Ecology and Conservation of a Trop ical Cloud Forest, N. M., Nadkarni and N. T. Wheelright, ed. Oxford University Press, Oxford, NY, pp. 419. Williams, D. A. and M. F. Lawton. Brown Jays: complex sociality in colonizing species. In: Monteverde: Ecology and Conservation of a Tropical Cloud Forest, N. M., Nadkarni and N. T. Wheelright, ed. Oxford University Press, Oxford, NY, pp. 212 213. Winnett Murray, K. 2000. Choosiness and productivity in wrens of forests, fragments, and farms. In: Monteverde: Ecology and Conservation of a Tropical Cl oud Forest, N. M., Nadkarni and N. T. Wheelright, ed. Oxford University Press, Oxford, NY, pp. 208. Young, B. E. 2000. How have humans affected bird populations? In: Monteverde: Ecology and Conservation of a Tropical Cloud Forest, N. M., Nadkarni and N. T. Wheelright, ed. Oxford University Press, Oxford, NY, pp. 433 444. Young, B. E. and D. B. McDonald. 2000 Birds. In: Monteverde: Ecology and Conservation of a Tropical Cloud Forest, N. M., Nadkarni and N. T. Wheelright, ed. Oxford University Press, Oxfor d, NY, pp. 196. Zartman, C. E. 2003. Habitat fragmentation impacts on epiphyllous bryophyte communities in Central Amazonia. Ecology. 84: 948 954.
7 Day Time and Order of Sites Being Sampled 7:00 10:00AM 2:00 5:00PM 1 Sites 1,2,3,4,5,6 Sites 7,8,9,10,11,12 2 Sites 7,8,9,10,11,12 Sites 1,2,3,4,5,6 3 Sites 6,1,2,3,4,5 Sites 12,7,8,9,10,11 4 Sites 12,7,8,9,10,11 Sites 6,1,2,3,4,5 5 Sites 5,6,1,2,3,4 Sites 11,12,7,8,9,10 6 Sites 11,12,7,8,9,10 Sites 5,6,1,2,3,4 7 Sites 4,5,6,1,2,3 Sites 10,11,12,7,8,9 8 Sites 10,11, 12,7,8,9 Sites 4,5,6,1,2,3 9 Sites 3,4,5,6,1,2 Sites 9,10,11,12,7,8 10 Sites 9,10,11,12,7,8 Sites 3 ,4,5,6,1,2 11 Sites 2,3,4,5,6,1 Sites 8,9,10,11,12,7 12 Sites 8,9,10,11,12,7 Sites 2,3,4,5,6,1 ________________________________________________________________________ Table 1. Rota tion order of 12 sample sites used over a 12 day period to avoid sampling bias experienced by increased activity in birds associated with the early morning and late afternoon hours. ________________________________________________________________________
8 ________________________________________________________________________ Figure 1. Number of tourists to visit the Monteverde Cloud Forest Preserve from 1983 to 2004. Ecotourism has increased dramati cally in Costa Rica in the last two decades reaching over 3.2 million in 2004. ________________________________________________________________________
9 Figure 2. Average species richness in a single observation period of 15min for touris t and closed sites over a 12 day period showing that the lowest average species rich site for tourist trails (8.000 +/ 1.128) is greater than the highest average species rich site for closed trails (7.833 +/ 1.642). All comparisons significantly differen t at p < 0.05 except 1 = 3 =4 = 5 = 6 = 9 = 10 = 11 = 12; 2 = 3; 7 = 8.
11 Species Tourist Trails Closed Trails Azure hooded Jay 9 3 Barred Forest Falcon 0 3 Black breaseted Wood Quail 4 8 Blackburian Warbler 1 0 Black faced Solitare 104 79 Black Guan 30 16 Blue crowned Motmot 1 0 Brown Jay 2 0 Buff fronted Quail Dove 0 1 Chesnut capped Brush Finch 18 6 Common Bush Tanager 158 123 Coppery headed Emerald 9 5 Emerald Toucanet 16 25 Golden browed Chlorophon ia 90 56 Green crowned Brilliant 7 2 Green eared Violet 1 0 Green Hermit 3 4 Grey breasted Wood Wren 123 86 Grey throated Leaf tosser 6 5 Hariy Woodpecker 0 2 Lineated Foilage gleaner 17 23 Mountain Robin 28 21 Ochraceous Wren 21 7 Olivacheous Wo odcreeper 1 1 Orange bellied Trogon 1 0 Prong billed Barbet 32 37 Purple throated Mountain Gem 28 15 Red faced Spinetail 1 0 Resplendent Quetzal 23 11 Ruddy ground Dove 4 10 Ruddy Treerunner 3 6 Silver throated Tanager 13 6 Slaty Antshrike 1 26 S laty backed Nightingale Thrush 94 94 Slat Throated Redstart 102 35 Smokybrown Woodpecker 1 2 Spotted Barbtail 2 0 Spotted Woodcreeper 10 23 Swainsons Thrush 5 3 3 Striped Warbler 35 18 Wattled Bellbird 1 0 Western Peewee 1 0 White throated Robin 1 08 80 White throated Spadebill 0 1 Wilson's Warbler 3 1 Yellow thighed Finch 1 0 Yellow throated Euphonia 1 0 Appendix 1. List of species found on both trail types and their total abundances as recorded over a 12 day period.