No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Conversational Noise Reduction as a Win–Win for Ecotourists and Rain Forest Birds in Peru
Abstract
For all its positive attributes, the recent expansion of ecotourism has resulted in greater influxes of people into natural areas, causing a range of impacts including behavioral disruptions among wildlife. How animals respond to conversation is poorly understood, but noise reduction may reduce the impact of ecotourists while simultaneously enhancing their experience with higher wildlife encounter rates. We tested the response of a rain forest bird community to noise by playing a recorded conversation while conducting point censuses in a terra firme forest in Tambopata, Peru. Fifty decibel conversation (approximately library speaking volume) caused declines of 35 percent in total detections and 33 percent in detected species richness. Birds reacted similarly to 60 dB (approximately the volume of an excited child): average detections declined by 39 percent and detected species richness by 37 percent. Specifically, noise-induced detection declines were manifest both in decreased vocalizations (37% decline) and decreased physical sightings (44% decline). Lowered detection frequencies indicate behavioral shifts. As vocalization is involved in territory defense, breeding behavior, and predator detection, strong noise responsiveness indicates potential harm for birds. Insectivores were the most affected bird guild, raising conservation concerns, as insectivorous birds are sensitive to habitat modification. Birds reacted strongly to noise both near an established ecotourist lodge and in an intact reserve, indicating an absence of habituation. Thus, as a method for reducing ecotourism's footprint on native fauna and improving tourist satisfaction with increased wildlife sightings, noise reduction seems promising, even for well-established ecotourist lodges.
... This is supported by anecdotal observations that 100 male howlers roar when boats pass with their motor on, but not when the motor is 101 turned off (Vanlangendonck et al., 2015). 102 Decreases in tourism-related noise may enhance visitor experience either by 103 leading to increased detection rates (Karp & Guevara, 2011) or reducing the likelihood 104 that animals will flee from tourists (Kinnaird & Brien, 1996 investigate whether there is a significant change in the behavior of pygmy marmosets 119 (Cebuella pygmaea) following playbacks of human speech, and whether this response 120 is stronger following louder and/or longer playbacks. We hypothesize that the 121 following behavioral responses will be seen following playbacks of human speech: 1) 122 pygmy marmosets will alter their behavior following playbacks, spending more time 123 vigilant, alert and engaging in self-directed behaviors, and less time engaged in 124 feeding, resting, social and calling behaviors; 2) individuals will move away from the 125 playback source, either by hiding and decreasing their visibility, or by completely 126 leaving the area. ...
... ). Following a 60 decibel105 playback of human conversation, detection of rainforest birds falls by 39%(Karp & Guevara, 2011). This pattern was documented both in an intact area of protected 107 forest and the area immediately surrounding an ecotourism lodge, indicating birds do not habituate to the noise of human conversation(Karp & Guevara, 2011). ...
... Following a 60 decibel105 playback of human conversation, detection of rainforest birds falls by 39%(Karp & Guevara, 2011). This pattern was documented both in an intact area of protected 107 forest and the area immediately surrounding an ecotourism lodge, indicating birds do not habituate to the noise of human conversation(Karp & Guevara, 2011). Similarly, 109 hoatzins (Opisthocomus hoazin) habituate to silent approaches by canoe but continue 110 to flee from 'noisy' approaches conducted with a conversational playback after 10 111 weeks of trials(Karp & Root, 2009).In spite of the potentially negative effects for visited species and tourists, the effects of tourist-generated noise on wild, visited primates. ...
Although potentially beneficial in terms of raising awareness and conservation funding, tourist visitation of wild primates can have negative impacts on visited groups. Tourism‐generated noise is a relatively understudied facet of ecotourism research, and the effects of tourist‐generated speech on free‐ranging, wild primates has never been explored previously. This study investigates the behavioral responses of 10 groups of pygmy marmosets (Cebuella pygmaea) to human speech. Through the use of an experimental playback study using recorded human speech, we show that pygmy marmosets within the Tamshiyacu‐Tahuayo Reserve, Peru, are significantly less visible, and often move completely out of sight after louder playbacks. Although no consistent differences were found in other behaviors with playback duration and volume, playbacks of human speech tended to increase the amount of time individuals were alert and decrease feeding and resting behaviors. Our results demonstrate that human speech can alter the behavior of visited primates, and identifies a decrease in primate visibility within the increasing volume. As all trials in this study took place near a marmoset group's feeding tree, moving out of sight from the visible study area is a particularly energetically costly behavior, and also has a negative effect on visitor enjoyment as it limits the time that they are able to view the target species. This response was not observed (nor was any other consistent behavior change) in control trials where the marmosets were exposed to human presence but not to speech, suggesting that negative tourist impacts can be reduced by encouraging tourists to refrain from speaking in the presence of visited primate groups.
... [356] Researchers tested the response of a rain forest bird community to noise by playing a recorded conversation while conducting bird surveys. [357] Conversation noise of 50 decibels (approximately library speaking volume) caused 35 percent fewer bird detections and reduced detected species richness by 33 percent. They found similar but slightly stronger results at 60 decibel conversation noise, approximately the volume of an excited child. ...
... Studies show that habitat specialists are reduced, and generalists -which include most species that tend to tolerate or be associated with human use -increased near trails and in fragmented habitats. [193,205,357,[409][410][411][412][413] In France, researchers used long-term Breeding Bird Survey data and associated landscape fragmentation metrics to assess whether habitat specialist bird species were more vulnerable to habitat fragmentation than generalist species. [412] Results fell on a gradient in which specialist bird species, but not generalists, declined with increasing fragmentation. ...
... [431] Other studies have found an apparent lack of habituation or sensitization for some bird species, particularly in areas of high disturbance. [254,285,357] Storch's global review of grouse studies found modest habituation-type responses for some species, but the majority of studies documented negative associations with recreational use and other human disturbance, with some evidence of sensitization. [432] Some studies simultaneously tested wildlife species' behavioral and physiological responses to disturbance. ...
Metro is the regional government in the Portland, Oregon area. Thanks to the region’s voters, the agency has acquired approximately 17,000 acres of natural areas to protect water quality, wildlife habitat and connect people with nature. The goal of this document is to better understand the trade-offs between different types and levels of recreational access in the context of our work to protect habitat and water quality, and provide access to nature in a growing urban area. Only by thoroughly understanding the effects of recreational activities on wildlife and water quality are we able to avoid, minimize and mitigate potential harm to the resources we are committed to protecting.
Recreation ecology is the scientific study of environmental impacts resulting from recreational activity in protected natural areas. The nature of a literature review is to summarize what has been studied, what has been learned, and what the experts have concluded. This document reviews the literature on overall and relative effects of three user groups – hikers, mountain bikers and equestrians – on trails, habitat, and wildlife to help inform ecologically appropriate placement and construction of trails in natural areas. Studies are reviewed from the U.S. and elsewhere, with a focus on soft-surface trails in natural areas. We included limited information about other non-motorized trail user groups such as trail runners and beach walkers. Motorized off-road vehicles were omitted from this review because they are generally not allowed on natural area trails within the urban and near-urban region. A previous literature review on the effects of dogs on wildlife and water quality is included as Appendix 1.
Studies vary in terminology for our recreational groups of interest. In this report “hiker” generally means a person walking along a trail for various reasons such as exercise, wildlife watching or moving between places. “Mountain biker” refers to a non-motorized bicycle rider on a soft or natural surface trail; alternative terms in the literature include off-road bicyclists or off-road cyclists. “Equestrian” refers to a person riding a horse on a trail. Throughout the text we refer to these as “user groups.”
Trails provide people with important opportunities to improve health and well-being, and providing access to nature is especially important in urban areas.[2-5] However, as indicated in various literature reviews, trails and trail use can damage natural areas including negatively affecting soils, vegetation, water quality, plants, and animals.[6-27] Damage to trails or habitats and negative effects on wildlife are more likely when trails are inappropriately located, designed, constructed, maintained or used, or when unauthorized trails are allowed to proliferate. These issues can also increase trail maintenance costs[28-30] and negatively affect visitors’ experience.[31-33]
This document reviews the types of recreational effects in Chapters 2-7, including information about user group-specific effects. Each chapter includes a summary of key points. Chapter 8 offers information on how to minimize, monitor and manage effects. Throughout the review we provide representative study examples with additional citations.
We paid close attention to the effects of recreation on wildlife (Chapters 6 and 7) because they are less well documented than physical effects such as erosion or vegetation damage. Scientific names for species mentioned in the text are in Appendix 2. For wildlife, human disturbance increases animals’ stress and can cause them to hide, change behavior or flee. Some species, such as those that do well in urban areas, are generalists and can tolerate human disturbance. Other species such as pregnant animals, long-distance migrants, and habitat specialists tend to be more stressed and displaced by trail users. Some species may permanently leave a natural area.
Figure 1 illustrates the relationships between environmental, trail design, recreational use and their effects on trail damage, water quality, vegetation damage and wildlife...
... Ecotourism has been highlighted as a sustainable economic opportunity in Madre de Dios (Csillik & Asner, 2020;Doan, 2013;Kirkby et al., 2010;Salvador, Clavero, & Leite Pitman, 2011). However, ecotourism can result in more interactions between humans and wildlife, which may generate disturbances (Karp & Guevara, 2011). Minimizing the impacts of ecotourism on wildlife is necessary to ensure the long-term sustainability of this activity and tourist satisfaction with wildlife sightings (Lee et al., 2017). ...
... Minimizing the impacts of ecotourism on wildlife is necessary to ensure the long-term sustainability of this activity and tourist satisfaction with wildlife sightings (Lee et al., 2017). Tourism companies, communities, researchers, and governments need to work together to create and implement guidelines for fauna observation throughout the region, including noise reduction and specific guidelines for clay-lick observation (Karp & Guevara, 2011;Lee et al., 2017). ...
... In some cases, birds have been found to become sensitized to recreation, e.g., shorebirds, in response to pedestrians, dogs, and cars (Pfister et al. 1992); and grouse, especially hunted populations (Storch 2013). Meanwhile, other studies have noted a lack of sensitization, particularly in areas of high disturbance, (e.g., shorebirds, in response to walkers, joggers, and dog-walkers) (Glover et al. 2011, Gray 2006; and insectivores in response to conversational noise in a Peruvian rain forest (Karp and Guevara 2011). ...
... Habitat generalist bird species have been found to increase near trails and fragmented habitats, while specialists have lower abundance in areas with human use (Burhans and Thompson 2006, Canadian Wildlife Service 2007, Devictor et al. 2008, Heil et al. 2006, Karp and Guevara 2011, Mallord et al. 2007, Miller et al. 1998, Morelli et al. 2016. In a study comparing recreational and control areas in woodland and grassland areas near Boulder, Colorado, most species were found to flush or become alert to humans within approximately 75 m from trails (Miller et al. 1998). ...
... En general, los efectos negativos de las actividades de turismo se deben a que los animales perciben la presencia de los turistas como un riesgo por depredación (Larson et al., 2016). Más de la mitad de los estudios con indicadores de abundancia y diversidad mostraron un efecto negativo como la reducción de la riqueza y abundancia en la Mata Atlántica brasileña (Furtado et al., 2015), disminución de la detección de aves (Karp & Guevara, 2011) y el menor registro de aves y mamíferos en Perú (Peña-Candia et al., 2019). ...
Wildlife tourism can have a positive impact on biodiversity conservation, although it can also affect the well-being of wildlife, causing changes in their behavior, physiology and even death. Therefore, the aim of this study was to conduct a systematic literature review of the impact of tourism on wildlife in South America, to identify the animals involved, types of tourism, indicators used to assess welfare, effects produced and recommendations provided by the authors. To carry out this study, the PRISMA methodology was used and platforms such as Google Scholar®, SciELO Citation Index®, Redalyc® and MEDLINE were examined, considering original articles and short communications from 2011 to 2022. After a rigorous selection process, a total of 30 articles were analyzed. The studies analyzed were mostly in English and conducted in Brazil, Argentina and Peru. They focused mainly on mammals, ecotourism and wildlife tourism, using behavioral indicators followed by diversity and abundance, and to a lesser extent, physiological indicators. Regarding the evaluated impacts related to human activity, it was found that human presence or contact (43.3%) and vehicles or boats (20.0%) were the predominant factors, causing a negative effect in 46.7% of the studies, followed by a mixed impact in 30% and no effect in 23.3%. The main recommendations for minimizing the impact of tourism on wildlife include regulating the behavior of tour operators and tourists, such as controlling noise, the number of visitors and the distance of approach, and the creation of exclusive no-tourist zones. In addition, it is considered necessary to carry out more studies and update policies to improve the sustainability of wildlife tourism.
... Although the effects of noise specifically from ecotourism remain poorly quantified (Buxton et al., 2017a;Potvin et al., 2021) there have been numerous attempts to evaluate the effects of ecotourism, and its associated activities, on local wildlife (Reviewed in: Brandt & Buckley, 2018Geffroy et al., 2015Green & Higginbottom, 2000;Shannon et al., 2016;Steven et al., 2011). Those studies that have investigated noise effects of certain ecotourist activities have found that even activities such as having conversations while hiking can produce levels of noise that impacts surrounding wildlife (Karp & Guevara, 2011). There are, however, few consistencies in the results of studies quantifying the effects of ecotourism on animals. ...
Investigations into how ecotourist resorts and their visitors impact local ecosystems and their wildlife have produced mixed results. One characteristic of ecotourist infrastructure is anthropogenic noise, and especially how fluctuations of visitors contribute to it. Furthermore, we do not understand how these noise levels influence animal species richness and/or assemblages. Here, we used passive acoustic recording over nine months to quantify how variation in weekly and seasonal human activity influence local bird assemblages at a popular ecotourist resort situated on K’gari (Fraser Island), Australia, a UNESCO World Heritage site and an Important Bird Area (Birdlife International). Background noise levels were highest during peak tourist season, especially proximate to main buildings. This noise was primarily associated with machinery and vehicles, but not human voices or music. Bird species richness correlated with noise (levels and detections), but did not appear to be sensitive to peak seasons or human voices. Community composition, however, was influenced by temporal and spatial fluctuations across peak tourist seasons. This study has implications for the development and maintenance of ecotourist infrastructure attempting to support visitors seeking sightings of rare or sensitive bird species and highlights anthropogenic noise as an important consideration for the industry.
... We therefore predicted a decrease in detection probability (p) for both avian groups in all treatments reflecting these lower activity patterns. Also, elevated sound levels from anthropogenic sources has been shown to decrease bird abundance and alter distributions (Francis et al., 2009;McClure et al., 2013;Proppe et al., 2013), so we believed that birds would avoid settling in louder areas and thus predicted decreased occupancy probabilities (Ψ) for both ground foraging and insectivorous birds, but likely with a stronger decline for insectivorous birds due to their apparent heightened sensitivity to sound (Canaday & Rivadeneyra, 2001;Karp & Guevara, 2011). ...
A growing body of research focuses on how background sounds shape and alter critical elements of animals’ lives, such as foraging behavior, habitat use, and ecological interactions (Bradbury & Vehrencamp, 2011; Barber et al., 2010; Kight & Swaddle, 2011; Shannon et al., 2016). Much of this research has centered on the effects of anthropogenic noise (Dominoni et al., 2020; Francis & Barber, 2013; Ortega, 2012; Swaddle et al., 2015), but recent studies have also revealed that natural sound sources can influence animal behavior (Davidson et al., 2017; Le et al., 2019). Natural sounds, such as crashing surf, can create conditions where signaling and listening are difficult, but how this influences different species’ ecological interactions are unknown. To study the effects of crashing surf sound we experimentally introduced landscape-level acoustic playbacks where surf sound was not naturally present to create a “phantom ocean”. Phantom ocean treatment sites were employed alongside higher frequency “shifted” treatment sites to test for frequency-dependent effects, “real ocean” sites where surf sound was endemic, and ambient control sites. The phantom and shifted treatments were played continuously during the spring and summer of 2017-2019. Within this acoustic experimental landscape we conducted multiple studies to test the effects of crashing surf sound on animal behavior, habitat use, and ecological interactions. Through an artificial caterpillar predation experiment modeled after Roslin et al. (2017), we found that when exposed to natural sound treatments the foraging activity of rodents and arthropods increased, while that of birds declined. A potential explanation for this pattern includes taxon-specific responses reflecting different perceived risk-reward trade-offs in natural sound conditions. To follow this up we performed occupancy modeling on data collected by camera traps set within our system. We observed different responses among groups of species with different functional roles in the community for both detection (p) and occupancy (Ψ) probabilities. Our combined results indicate different species and functional groups have unique foraging behavior and patch use responses to natural sounds, likely based on their ecological interactions. Specifically, Cricetid rodents are likely more active in areas exposed to natural sounds, possibly due to lower perceived predation risk because mesocarnivores are less active. Insectivorous birds are also likely less active under natural sounds conditions, although the frequency of the sound, and the body size and diet of the bird appear influential. Together these findings suggest that natural sounds shape not only individual behavioral adjustments, but also multi-trophic, community level interactions. Our results show that natural sounds are an important driver of ecological interactions, but much remains to be uncovered. The mechanisms by which natural sounds influence individuals, populations, and many other aspects of ecology remain unexplored and provide fertile ground for future inquiry.
... A second implication of our findings involves managing protected areas to promote hearing natural sounds and experiencing wildlife. Observing wildlife is a key motivation to visit parks and protected areas [64], yet human presence can reduce the abundance of wildlife or displace them away from human activity, which makes them more difficult to observe [65]. Recent research shows educational signs instructing visitors to reduce their noise significantly reduced noise levels, increased bird biodiversity, increased visitor perceptions of bird biodiversity and improved visitor experiences at Muir Woods National Monument [21,66]. ...
Spending time in nature is known to benefit human health and well-being, but evidence is mixed as to whether biodiversity or perceptions of biodiver- sity contribute to these benefits. Perhaps more importantly, little is known about the sensory modalities by which humans perceive biodiversity and obtain benefits from their interactions with nature. Here, we used a ‘phan- tom birdsong chorus’ consisting of hidden speakers to experimentally increase audible birdsong biodiversity during ‘on’ and ‘off’ (i.e. ambient conditions) blocks on two trails to study the role of audition in biodiversity perception and self-reported well-being among hikers. Hikers exposed to the phantom chorus reported higher levels of restorative effects compared to those that experienced ambient conditions on both trails; however, increased restorative effects were directly linked to the phantom chorus on one trail and indirectly linked to the phantom chorus on the other trail through perceptions of avian biodiversity. Our findings add to a growing body of evidence linking mental health to nature experiences and suggest that audi- tion is an important modality by which natural environments confer restorative effects. Finally, our results suggest that maintaining or improving natural soundscapes within protected areas may be an important component to maximizing human experiences.
... If an airport is located in the range of the migration route of birds, a large number of birds will appear around the airport during the migratory season. Furthermore, if the runway direction of the airport is perpendicular to the bird migration route, the possibility of bird strikes will increase significantly, and the light and the noise of airports will also have an impact on a large number of migratory birds (Karp and Guevara, 2011;Russ et al., 2015;Sierro et al., 2017;Winger et al., 2019). Similarly, the Delphi method was used to score the factors of the two airport sites based on the relationship between the airport location and the bird migration route. ...
The construction and operation of a civil airport will inevitably destroy the biodiversity and ecosystem components. Especially when located on bird migration routes, the emergence of a civil airport will have a large impact on birds, resulting in immeasurable ecological loss. Therefore, it is necessary to carry out an evaluation of the ecological impact on birds at the airport site selection stage for the sustainable development of humans and the nature. Geographically, Dalian, China, is an important site in the bird migration routes in northeast Asia, and the National Conservation Area of Snake Island and Laotieshan Mountain located in the south of Dalian has been included in the Man and Biosphere Programme (MBP) network as a biosphere reserve. Therefore, the expansion plan of a new civil airport in this region is a major challenge to the bird ecology. Here, using the detailed investigation data about migratory birds in Dalian, we evaluate the impact of different site schemes on the bird ecology by an expert-based approach and choose the more favourable one for bird ecological environments. The innovative attempt to a civil airport site selection based on the bird ecological conservation presented in this paper is of great significance for improving airport site planning and exploring the sustainable development of airports and the bird ecology around the world. Keywords: Airport, Site selection, Bird, Ecology, Expert-based, AHP
... In fact, recent evidence shows that broadcasting traffic noise in otherwise quiet habitats can experimentally induce many of the ecological effects of roads on wildlife and degrade habitat quality (McClure et al., 2013Ware et al., 2015). Anthropogenic noise from other sources (e.g., energy sector noise - Bayne et al., 2008;Francis et al., 2009;talking visitors e Pilcher et al., 2009;Karp and Guevara, 2011; sonar and other sounds from military activities, Hatch and Fristrup, 2009) is an increasingly recognized cost of human activities; a cost imposed on both visitors (Newman et al., 2010b) and biodiversity in protected areas (Hatch and Fristrup, 2009). The potential for its influence is so great that the NPS created a new program e the Division of Natural Sounds and Night Skies e devoted to conserving the sounds of nature (Newman et al., 2013). ...
Protected areas are critical locations worldwide for biodiversity preservation and offer important opportunities for increasingly urbanized humans to experience nature. However, biodiversity preservation and visitor access are often at odds and creative solutions are needed to safeguard protected area natural resources in the face of high visitor use. Managing human impacts to natural soundscapes could serve as a powerful tool for resolving these conflicting objectives. Here, we review emerging research that demonstrates that the acoustic environment is critical to wildlife and that sounds shape the quality of nature-based experiences for humans. Human-made noise is known to affect animal behavior, distributions and reproductive success, and the organization of ecological communities. Additionally, new research suggests that interactions with nature, including natural sounds, confer benefits to human welfare termed psychological ecosystem services. In areas influenced by noise, elevated human-made noise not only limits the variety and abundance of organisms accessible to outdoor recreationists, but also impairs their capacity to perceive the wildlife that remains. Thus soundscape changes can degrade, and potentially limit the benefits derived from experiences with nature via indirect and direct mechanisms. We discuss the effects of noise on wildlife and visitors through the concept of listening area and demonstrate how the perceptual worlds of both birds and humans are reduced by noise. Finally, we discuss how management of soundscapes in protected areas may be an innovative solution to safeguarding both and recommend several key questions and research directions to stimulate new research.
... In fact, recent evidence shows that broadcasting traffic noise in otherwise quiet habitats can experimentally induce many of the ecological effects of roads on wildlife and degrade habitat quality (McClure et al., 2013Ware et al., 2015). Anthropogenic noise from other sources (e.g., energy sector noise - Bayne et al., 2008;Francis et al., 2009;talking visitors e Pilcher et al., 2009;Karp and Guevara, 2011; sonar and other sounds from military activities, Hatch and Fristrup, 2009) is an increasingly recognized cost of human activities; a cost imposed on both visitors (Newman et al., 2010b) and biodiversity in protected areas (Hatch and Fristrup, 2009). The potential for its influence is so great that the NPS created a new program e the Division of Natural Sounds and Night Skies e devoted to conserving the sounds of nature (Newman et al., 2013). ...
Throughout the world, birds represent the primary type of wildlife that people experience on a daily basis. However, a growing body of evidence suggests that alterations to the acoustic environment can negatively affect birds as well as humans in a variety of ways, and altered acoustics from noise pollution has the potential to influence human interactions with wild birds. Birds respond to approaching humans in a manner analogous to approaching predators, but the context of the interaction can also greatly influence the distance at which a bird initiates flight or escape behavior (i.e., flight initiation distance or FID). Here, we hypothesized that reliance on different sensory modalities to balance foraging and threat detection can influence how birds respond to approaching threats in the presence of background noise. We surveyed 12 songbird species in California and Wyoming and categorized each species into one of three foraging guilds: ground foragers, canopy gleaners, and hawking flycatchers and predicted FIDs to decrease, remain the same and increase with noise exposure, respectively. Contrary to expectations, the canopy gleaning and flycatching guilds exhibited mixed responses, with some species exhibiting unchanged FIDs with noise while others exhibited increased FIDs with noise. However, FIDs of all ground foraging species and one canopy gleaner decreased with noise levels. Additionally, we found no evidence of phylogenetic structure among species' mean FID responses and only weak phylogenetic structure for the relationship between FIDs and noise levels. Although our results provide mixed support for foraging strategy as a predictor of bird response to noise, our finding that most of the species we surveyed have shorter FIDs with increases in noise levels suggest that human observers may be able to approach ground foraging species more closely under noisy conditions. From an ecological perspective, however, it remains unclear whether these mixed responses translate into lost foraging opportunity for hypervigilant birds that flee a threat too soon or greater predation risk due to impaired surveillance for those that only respond once approaching threats are near.
... Regression trees are useful when there are many explanatory variables and we need to identify which of them has the strongest impact on a continuous response variable (Crawley 2007). They have been increasingly used in the ecological literature (Davidson et al. 2009, Karp & Guevara 2011. In regression trees, the importance of each explanatory variable is assessed based on a recursive partitioning of the data into successively smaller groups with binary splits. ...
Background/Question/Methods
Intensification of land use is considered the main driver of global biodiversity change in terrestrial ecosystems. Because a large proportion of global biodiversity is nowadays located in fragmented landscapes, understanding species responses to changes in landscape spatial pattern is necessary for designing appropriate conservation and management strategies. We assessed the effects of five landscape-scale metrics (forest cover, number of forest patches, total forest edge, connectivity, and matrix permeability) and three patch-scale metrics (patch size, shape, and isolation) on number of species and patch occupancy of mid- and large-sized Neotropical mammals in the fragmented Lacandona rainforest, southeastern Mexico. Using camera traps, track surveys and visual censuses, we sampled terrestrial mammal assemblages in 28 sites, 24 focal forest patches and four control areas within a continuous forest. The landscape-scale metrics were measured at two different spatial scales: within a 100-ha buffer, and within a 500-ha buffer from the center of each sampling site.
Results/Conclusions
A total of 21 species from 13 families were recorded. The number of species increased with patch size and shape complexity at the patch scale. However, the landscape attributes influencing mammal assemblages varied with the spatial scale: the number of species increased with matrix permeability when considering 100-ha buffers, but tended to decrease in landscapes with higher fragmentation degree when considering 500-ha buffers. The landscape- and patch-scale metrics that predicted the presence of each individual species within the focal patches were different, but in general, the landscape-scale metrics were better predictors. To conserve mammal assemblages in the region it is necessary to maintain larger patches and prevent forest patches from being increasingly isolated from each other by creating vegetation corridors, especially riparian corridors. More multi-scale and long-term studies are vital to comprehend how species respond to the new human-modified landscapes.
... Regression trees are useful when there are many explanatory variables and we need to identify which of them has the strongest impact on a continuous response variable (Crawley 2007). They have been increasingly used in the ecological literature (Davidson et al. 2009, Karp & Guevara 2011. In regression trees, the importance of each explanatory variable is assessed based on a recursive partitioning of the data into successively smaller groups with binary splits. ...
Understanding the response of biodiversity to land-use changes is an important challenge for ecologists. We assessed the effects of five landscape metrics (forest cover, number of patches, edge density, mean inter-patch isolation distance and matrix quality) and three patch metrics (patch size, shape and isolation) on the number of species and patch occupancy of medium- and large-sized terrestrial mammals in the fragmented Lacandona rain forest, Mexico. We sampled mammal assemblages in 24 forest patches and four control areas within a continuous forest. The landscape metrics were measured within a 100-ha buffer, and within a 500-ha buffer from the centre of each sampling site. A total of 21 species from 13 families was recorded. The number of species increased with shape complexity and patch size at the patch scale, and with matrix quality within 100-ha landscapes. When considering 500-ha landscapes, only the number of patches (i.e. forest fragmentation level) tended to have a negative influence at the community level. Different landscape and patch metrics predicted the occurrence of each species within the sites. Our results indicate that there is a gradient of tolerance to forest cover change, from highly sensitive species to those tolerant of, or even benefited by, forest-cover change.
... As with habitat change, several types of recreation have been shown to affect animal behaviour including mountain-biking, vehicle use, wildlife-watching and other forest activities such as paintballing and orienteering. Karp and Guevara (2011) show that even average levels of conversational noise can have an impact. However, most widely reported is the disturbance caused by walking, including with dogs. ...
Forests are popular locations for outdoor recreation and there is considerable evidence highlighting the positive social impacts of these activities. There is also a body of research outlining the range of potentially negative impacts of recreation on wildlife and habitats. This paper provides a summary of current social and natural scientific knowledge on disturbance caused by walking, cycling, mountain biking, horse riding, off-road vehicles use, camping, and some other recreational activities in forests. We identify more than 40 ecological studies of recreational impacts on forests. Greatest attention has been directed towards walking as an activity and the impacts upon birds, soils and flora although long-term ecological studies of wildlife or habitat disturbance are scarce. Impacts include trampling by foot, hoof and tyre, animal behaviour change and the spread of pests and pathogens. Considerably less work has been carried out on the social dimensions of recreational disturbance. In this article the authors draw on behaviour theory in an attempt to identify the key factors influencing human behaviour in the context of recreational disturbance. Cognitive theories highlight the importance of attitudes and behavioural control, whilst social practice theories emphasise the impact of behavioural routines and contexts. Management actions may be better targeted at promoting alternative behaviours rather than trying to prevent current ‘problem’ behaviours. We advocate greater engagement with these theories to better integrate social science with ecological studies, and improve understanding and management of interactions between recreation needs and conservation.
... In particular in the case of specialized birdwatchers, the rarer an observed species is, the higher is its recreational value (Booth, Gaston, Evans, & Armsworth, 2011). Although rarity sometimes brings tourism in conflict with the protection of a resource (Karp & Guevara, 2011;Kerbiriou et al., 2009), the direct negative impacts of protection on tourism may be offset by the future benefits related to maintaining this resource (Gilbert & Halstead, 1997). This highlights the sustainability aspect of tourism; indeed, not all of what is broadly called ecotourism can be defined as sustainable (Sharpley, 2006;Simpson, 2009;Steele, 1995). ...
... Studies that fail to make this distinction may identify tourism impacts on biodiversity and suggest mitigation measures (e.g. Williams et al., 2009;Karp and Guevara, 2011). However, they do not measure ecotourism's ability to conserve biodiversity in a threatened habitat. ...
... Leski et al. 2010;Willig et al. 2011), regression trees are being increasingly used for analysis of complex ecological data (De'Ath and Fabricius 2000). Regression trees are especially robust if hundreds of trees are generated using random subsets of the original data, and only those partitions and branches that are consistent over a large proportion of trees are used (Breiman 2001;Karp and Guevara 2011). Results from our regression trees suggested that different functional groups of macrofungi respond differentially to environment factors. ...
Gradient analysis is rarely used in studies of fungal communities. Data on macromycetes from eight sites along an elevation
gradient in central Veracruz, Mexico, were used to demonstrate methods for gradient analysis that can be applied to studies
of communities of fungi. Selected sites from 100 to 3,500m altitude represent tropical dry forest, tropical montane cloud
forest, conifer forest, and their ecotones. From May to October 2010, macromycetes were collected monthly within ten 10×10m
permanent plots per site. In total, 672 individuals of 213 species of macromycetes were recorded. Models for richness and
diversity for all macromycete and ectomycorrhizal communities displayed peaks in the mid-part of the gradient, and a tendency
to increase with elevation, whereas xylophagous fungi displayed a peak in the mid-lower part but tended to decrease with elevation.
Cluster and Maximum Likelihood analyses distinguished four communities for both macromycetes and trees, but plant and fungal
communities were only partly concordant. Canonical correspondence analysis indicated that macromycete distribution along the
gradient is related to slope, relative humidity, soil temperature, soil water content, canopy openness, and litter depth.
Spearman’s correlation and regression trees suggested that air and soil temperature, relative humidity, soil water content,
canopy openness, vegetation structure and tree species richness were most strongly related to macrofungal functional groups,
but these environmental variables were often correlated to the forest type and may not be causal. Variation in the environment
along the elevation gradient differentially affected macromycete functional groups. Results from the different methods used
in this work were concordant and showed significant patterns.
KeywordsAltitudinal gradient–Community turnover–Distribution–Ectomycorrhizal–Environment variation–Macrofungal diversity–Methods–Xylophagous
During the COVID-19 pandemic, humanity temporarily retired from the outdoors. The strict lockdown measures in Spain coincided with the onset of the nesting season of birds, thriving in an unusually quiet environment. Here, we have recorded in forests near San Lorenzo de El Escorial (Central Spain) during the lockdown period in 2020, and the closer to normal spring in 2021. We found strong differences in soundscapes by recording year and location, regardless of the effects of meteorology and human mobility. Species altered their behaviour by increasing their calling intensity during 2021 to cope with higher noise levels, however, acoustic activity was generally less diverse and complex. The difference between years was particularly detrimental for the highest-pitched biophony in 2021. We interpret that an extreme snowfall, Filomena, may have caused a mortality event with lasting effects in the community during the 2021 spring. Since extreme climatic events are likely going to keep happening in the area due to climate change, our data is a useful baseline to guide future conservation efforts, and examine how our activity and climate change are changing the soundscapes of Spanish Mediterranean forests.
Rainforests provide exceptional spaces for nature-based tourism activities attracting large numbers of visitors. Simultaneously, tourism activities may create environmental, social and economic impacts that require management in order to conserve sensitive rainforest environments. Rainforest tourism constitutes a travel sector that receives growing interest worldwide. This study presents a timely review of current knowledge and research gaps in a new conceptual model to give recommendations for a future research agenda. Through a systematic quantitative review, the study identified 48 peer-reviewed journal articles addressing conservation and management topics (33), followed by visitor-related research (23), impacts (10), and finally community and stakeholder research (3) of rainforest tourism, published between 1975 and 2019. The majority of research focused on management issues relating to policy development, planning, education and conservation measures. A strong geographic bias was noted with very limited research available for rainforest regions in Africa and Asia. Future research should be concerned with expanding and linking rainforest research across countries, and filling knowledge gaps around visitor monitoring, specific impacts and causes, and the complexity of community and stakeholder involvement in managing impacts. Protocols may need to be established to facilitate the design and delivery of standardised research approaches across the globe.
Ecotourism, a subset of tourism aiming to benefit both livelihoods and the environment, is a growing sector of the travel market, generating significant revenue and affecting socio-ecological systems at a global scale. Ecotourism is often touted as a “non-consumptive” use of biodiversity, even in light of existing literature that shows detrimental impacts of tourism on wild populations. Few studies have synthesized existing data and made recommendations that can be directly applied to existing wildlife-based ecotourism (WBE) enterprises. Using content analysis techniques, this study analyzes ecological, socio-political and economic management contexts of 208 recent WBE case studies. Findings demonstrate extensive and varied impacts of WBE on wildlife, including both indirect impacts related to the reduction of threats, and direct impacts resulting from the tourism activities themselves. Exploitative practices and poaching were reported as most commonly reduced by WBE, while poaching and hunting were also cited as least frequently reduced. Negative behavioral impacts were the most frequently reported direct effects of WBE on wildlife. The most common positive direct impacts were demographic changes at WBE sites. Reported impacts were influenced by species characteristics and activities associated with WBE projects. Many successful mitigation strategies and best-practice recommendations were reported in the literature. This analysis supports the coupling of existing frameworks on wildlife tourism and socio-ecological systems to identify strategies likely to maximize positive conservation outcomes of WBE sites. These findings support the development of project and policy guidelines for WBE as a sustainable conservation-development strategy.
Global increases in environmental noise levels arising from expansion ofhuman populations, transportation networks, and resource extraction have catalysed a recent surge of research into the effects of noise on wildlife. Synthesising a coherent understanding of the biological consequences of noise from this literature is challenging. Taxonomic groups vary in auditory capabilities.. wide range of noise sources and exposure levels occur, and many kinds of biological responses have been observed, ranging faint individual behaviours to changes in ecological conununities. Also, noise is one of several environmental effects generated by human activities, so researchers must contend with potentially confounding explanations for biological responses. Nonetheless, it is clear that noise presents diverse threats to species and ecosystems and salient patterns are emerging to help inform future natural resource-management decisions. We conducted a systematic and standardised review of the scientific literature published from 1990 to 2013 on the effects of anthropogenic noise on wildlife, including both terrestrial and aquatic studies. Research to date has concentrated predominantly On European and North American species that rely on vocal corrununication, with approximately two-thirds of the data set focussing on songbirds and marine mammals. The majority of studies documented effects from noise, including altered vocal behaviour to mitigate masking, reduced abundance in noisy habitats, changes in vigilance and foraging behaviour, and impacts on individual fitness and the structure of ecological communities. This literature survey shows that terrestrial wildlife responses begin at noise levels of approximately 40 dIlA, and 20% of papers documented impacts below 50 dBA. Our analysis highlights the utility of existing scientific information concerning, the effects of anthropogenic noise on Wikllife for predicting potential outcomes of noise exposure and implementing meaningful mitigation measures. future research directions that Would support more comprehensive predictions regarding the magnitude and severity of noise impacts include: broadening taxonomic and geographical scope, exploring interacting stressors, conducting larger-scale studies, testing mitigation approaches, standardising reporting of acoustic metrics, and assessing the biological response to noise-source removal or mitigation. The broad volume of existing information concerning the effects of anthropogenic, noise on wildlife offers a valuable resource to assist scientists, industry, and natural-resource managers in predicting potential ()incomes of noise exposure.
Global increases in environmental noise levels – arising from expansion of human populations, transportation networks, and resource extraction – have catalysed a recent surge of research into the effects of noise on wildlife. Synthesising a coherent understanding of the biological consequences of noise from this literature is challenging. Taxonomic groups vary in auditory capabilities. A wide range of noise sources and exposure levels occur, and many kinds of biological responses have been observed, ranging from individual behaviours to changes in ecological communities. Also, noise is one of several environmental effects generated by human activities, so researchers must contend with potentially confounding explanations for biological responses. Nonetheless, it is clear that noise presents diverse threats to species and ecosystems and salient patterns are emerging to help inform future natural resource-management decisions. We conducted a systematic and standardised review of the scientific literature published from 1990 to 2013 on the effects of anthropogenic noise on wildlife, including both terrestrial and aquatic studies. Research to date has concentrated predominantly on European and North American species that rely on vocal communication, with approximately two-thirds of the data set focussing on songbirds and marine mammals. The majority of studies documented effects from noise, including altered vocal behaviour to mitigate masking, reduced abundance in noisy habitats, changes in vigilance and foraging behaviour, and impacts on individual fitness and the structure of ecological communities. This literature survey shows that terrestrial wildlife responses begin at noise levels of approximately 40 dBA, and 20% of papers documented impacts below 50 dBA. Our analysis highlights the utility of existing scientific information concerning the effects of anthropogenic noise on wildlife for predicting potential outcomes of noise exposure and implementing meaningful mitigation measures. Future research directions that would support more comprehensive predictions regarding the magnitude and severity of noise impacts include: broadening taxonomic and geographical scope, exploring interacting stressors, conducting larger-scale studies, testing mitigation approaches, standardising reporting of acoustic metrics, and assessing the biological response to noise-source removal or mitigation. The broad volume of existing information concerning the effects of anthropogenic noise on wildlife offers a valuable resource to assist scientists, industry, and natural-resource managers in predicting potential outcomes of noise exposure.
Species do not respond identically to the presence of humans, and this may have consequences at higher-levels of ecological organization. We established bird transects on and off recreational trails in the high Córdoba Mountains of Argentina, a biogeographic island characterized by high levels of endemism, to examine the effect of human visitation at three different levels: (a) community (avian species richness and diversity), (b) guild (relative density of carnivores, granivores, insectivores, and omnivores), and (c) population (relative density of individual bird species). Human presence in the high Córdoba Mountains decreased avian species richness and diversity, and reduced insectivorous relative density, but we did not detect significant effects on granivores, omnivores, and carnivores. At the population level, 6 of 28 species were negatively affected by human visitation; four of these species are of conservation concern. Our results show negative responses to recreationists at multiple levels (e.g., reductions in density, displacement of species from highly visited areas), which may be related to spatial and temporal access to suitable resources, physical disturbance or species-specific tolerance thresholds. Our study area had lower levels of human visitation relative to other protected areas in the Northern Hemisphere, which raises the issue of whether this kind of biogeographically isolated habitat may be too fragile to sustain increasing levels of tourism.
Classification and regression trees are ideally suited for the analysis of complex ecological data. For such data, we require flexible and robust analytical methods, which can deal with nonlinear relationships, high-order interactions, and missing values. Despite such difficulties, the methods should be simple to understand and give easily interpretable results. Trees explain variation of a single response variable by repeatedly splitting the data into more homogeneous groups, using combinations of explanatory variables that may be categorical and/or numeric. Each group is characterized by a typical value of the response variable, the number of observations in the group, and the values of the explanatory variables that define it. The tree is represented graphically, and this aids exploration and understanding. Trees can be used for interactive exploration and for description and prediction of patterns and processes. Advantages of trees include: (1) the flexibility to handle a broad range of response types, including numeric, categorical, ratings, and survival data; (2) invariance to monotonic transformations of the explanatory variables; (3) ease and robustness of construction; (4) case of interpretation; and (5) the ability to handle missing values in both response and explanatory variables. Thus, trees complement or represent an alternative to many traditional statistical techniques, including multiple regression, analysis of variance, logistic regression, log-linear models, linear discriminant analysis, and survival models. We use classification and regression trees to analyze survey data from the Australian central Great Barrier Reef, comprising abundances of soft coral taxa (Cnidaria: Octocorallia) and physical and spatial environmental information. Regression tree analyses showed that dense aggregations, typically formed by three taxa, were restricted to distinct habitat types, each of which was defined by combinations of 3-4 environmental variables. The habitat definitions were consistent with known experimental findings on the nutrition of these taxa. When used separately, physical and spatial variables were similarly strong predictors of abundances and lost little in comparison with their joint use. The spatial variables are thus effective surrogates for the physical variables in this extensive reef complex, where information on the physical environment is often not available. Finally, we compare the use of regression trees and linear models for the analysis of these data and show how linear models fail to find patterns uncovered by the trees.
Nature tourism has great potential for negatively impacting animals as tourists seek out rare and spectacular species. Ecotourism-induced stresses on animals may result in changes in population densities, species composition, and commu- nity structure. Tikal National Park is visited extensively by tourists, most of whom are concentrated around the Mayan ruins. Potential impacts of tourism in Tikal were evaluated by comparing the population densities of select species of mammals and birds in two regions of the park, with and without tourist traffic. Densities were estimated using visual line transects and distance sampling methods. Trends show the impact of ecotourism is species specific, with some species increasing in density, some decreasing, and others unaffected. An evaluation of the limitations and assumptions of the methods used provides a framework for consideration of the results. Given the potential negative impact of tourists on animals, national parks should develop management strategies to minimize these impacts, such as concentrating tourists in already disturbed areas.
Military helicopter training over the Lincoln National Forest (LNF) in southcentral New Mexico has been severely limited to protect nesting Mexican spotted owls (Strix occidentalis lucida). To evaluate nesting and nonnesting spotted owl responses to helicopter noise, we measured flush frequency, flush distance, alert behavior, response duration, prey delivery rates, female trips from the nest, and nest attentiveness during manipulated and nonmanipulated periods, 1995-96. Chain saws were included in our manipulations to increase experimental options and to facilitate comparative results. We analyzed stimulus events by measuring noise levels as unweighted one-third-octave band levels, applying frequency weighting to the resultant spectra, and calculating the sound exposure level for total sound energy (SEL) and the 0.5-sec equivalent maximum energy level (LEQ(max 0.5-sec)) for helicopters, and the 10-sec equivalent average energy level (LEQ(avg. 10-sec)) for chain saws. An owl-weighting (dBO) curve was estimated to emphasize the middle frequency range where strigiform owls have the highest hearing sensitivity. Manipulated and nonmanipulated nest sites did not differ in reproductive success (P = 0.59) or the number of young fledged (P = 0.12). As stimulus distance decreased, spotted owl flush frequency increased, regardless of stimulus type or season. We recorded no spotted owl flushes when noise stimuli were >105 m away. Spotted owls returned to predisturbance behavior within 10-15 min after a stimulus event. All adult flushes during the nesting season occurred after juveniles had left the nest. Spotted owl flush rates in response to helicopters did not differ between nonnesting (13.3%) and nesting seasons (13.6%; P = 0.34). Spotted owls did not flush when the SEL noise level for helicopters was less than or equal to 102 dBO (92 dBA) and the LEQ level for chain saws was less than or equal to 59 dBO (46 dBA). Chain saws were more disturbing to spotted owls than helicopter flights at comparable distances. Our data indicate a 105-m buffer zone for helicopter overflights on the LNF would minimize spotted owl flush response and any potential effects on nesting activity.
This paper describes studies undertaken during 1972 and 1973 to determine the extent of research activity on egg and chick mortality at a Glaucous-winged Gull colony on Colville Island, Washington. Our presence had no effect on egg mortality. There was no overall population decline but chick mortality increased in areas where our research was centered. Fifty-five percent of the mortality occurred during the first week after hatching. The increase in mortality resulted largely from chicks moving into adjacent territories and being attacked by neighboring adults as the result of our entering the chicks' home territory.
Question: Vascular epiphytes and hemiepiphytes (E/HE) in neotropical forests account for a large fraction of plant richness, but little is known of how the interplay between phorophyte architectural characteristics and habitat perturbation affect communities of E/HE.Location: Sabal mexicana forests in a coastal area of Veracruz, Mexico.Methods: We compared communities of E/HE on phorophytes with different architectural characteristics – the palm S. mexicana and non-palm phorophytes – in three environments: conserved sites, perturbed sites and small regenerated forest fragments. We combined traditional (abundance, species richness, similarity and complementarity indices) and more recent (phylogenetic diversity) metrics to describe the communities of E/HE.Results: Overall, we recorded 924 E/HE individuals (nine families, 16 genera and 21 species). The abundance and species richness of E/HE was higher on palms than on non-palm phorophytes. Abundance-based complementarities between phorophytes and sites were high. We detected clear changes in community structure of E/HE with habitat perturbation, but there were no effects on the phylogenetic diversity of the E/HE community. Palm phorophytes hosted a more phylogenetically diverse community of E/HE than did non-palm phorophytes.Conclusions: Palm phorophytes are key elements supporting the conservation of resilient communities of E/HE in S. mexicana forest. Habitat fragmentation has a strong effect on the structure of the E/HE community in S. mexicana forests. Ferns are the group of epiphytes most severely affected by habitat perturbation, but we detected no significant effect on the phylogenetic diversity of the community.
Cumulative impacts of logging and road building in a previously undisturbed tract of tropical rain forest in French Guiana were assessed by random sampling of the bird community and 1-km2 plot counts of diurnal raptors. Similar surveys were carried out during road construction and 15 years later within 5km of the road and were also compared with the undisturbed bird community of a nearby primary forest. The main disturbance was the change in forest structure brought about by logging and secondarily the road opening, the roadside second growth and the depletion of large vertebrates by hunting pressure. The responses of different bird guilds were highly divergent according to their natural habitat requirements, their diet and their vulnerability to hunting. They resulted in a moderate decrease in overall species richness and equitability. All species pooled, the abundance of 118 species was lowered, that of 45 species did not change appreciably and 89 were favored or even appeared. The guilds most affected were those with large body sizes, from terrestrial foragers to canopy frugivores, mostly by hunting, and the open understorey specialists, notably large insectivores and mixed flock members, because of changes in forest structure after logging. The guilds favored by logging and road opening were many of the hummingbirds, upper canopy frugivores and omnivores, and gap, edge or low secondary growth specialists. Recommendations to minimize the negative consequences of human exploitation in rain forests include reducing the width of deforested roadsides to no more than 10–15m on either side, implementing much more careful logging practices and strongly limiting hunting pressure in newly opened areas.
Exposure to ecotourists often disrupts animal behavior, which is known to contribute to heightened mortality rates. In the
Amazon, the emblematic, communal nesting Hoatzin (Opisthocomus hoazin) is frequently pursued by tourists eager for close views. Such encounters may cause heightened stress levels, and egg or
nestling predation due to decreased parental attendance to nests and nestlings. The effect of reducing conversational tourist
noise near wildlife is poorly understood, but represents one potential mechanism of mitigating the impacts of ecotourists
on wildlife. In this study, we approached Hoatzins by canoe, playing recorded tourist conversations at different volumes.
Both the distances from which we observed Hoatzins becoming agitated (e.g., clucking, defecation, etc.) and flush (e.g., flight
or climbing away) were positively correlated with volume. Within 10weeks Hoatzins began to habituate to silent approaches.
Tourist conversations, however, continued to elicit the same heightened disturbance responses throughout data collection.
Therefore, to have the best chance of seeing Hoatzins at a short distance and minimizing potentially negative disturbances,
ecotourists should cease all conversation. Although not tested, silence is probably the best strategy when looking for many
wildlife species.
The task of modeling the distribution of a large number of tree species under future climate scenarios presents unique challenges.
First, the model must be robust enough to handle climate data outside the current range without producing unacceptable instability
in the output. In addition, the technique should have automatic search mechanisms built in to select the most appropriate
values for input model parameters for each species so that minimal effort is required when these parameters are fine-tuned
for individual tree species. We evaluated four statistical models—Regression Tree Analysis (RTA), Bagging Trees (BT), Random
Forests (RF), and Multivariate Adaptive Regression Splines (MARS)—for predictive vegetation mapping under current and future
climate scenarios according to the Canadian Climate Centre global circulation model. To test, we applied these techniques
to four tree species common in the eastern United States: loblolly pine (Pinus taeda), sugar maple (Acer saccharum), American beech (Fagus grandifolia), and white oak (Quercus alba). When the four techniques were assessed with Kappa and fuzzy Kappa statistics, RF and BT were superior in reproducing current
importance value (a measure of basal area in addition to abundance) distributions for the four tree species, as derived from
approximately 100,000 USDA Forest Service’s Forest Inventory and Analysis plots. Future estimates of suitable habitat after
climate change were visually more reasonable with BT and RF, with slightly better performance by RF as assessed by Kappa statistics,
correlation estimates, and spatial distribution of importance values. Although RTA did not perform as well as BT and RF, it
provided interpretive models for species whose distributions were captured well by our current set of predictors. MARS was
adequate for predicting current distributions but unacceptable for future climate. We consider RTA, BT, and RF modeling approaches,
especially when used together to take advantage of their individual strengths, to be robust for predictive mapping and recommend
their inclusion in the ecological toolbox.
Species do not respond identically to the presence of humans, and this may have consequences at higher-levels of ecological
organization. We established bird transects on and off recreational trails in the high Córdoba Mountains of Argentina, a biogeographic
island characterized by high levels of endemism, to examine the effect of human visitation at three different levels: (a)
community (avian species richness and diversity), (b) guild (relative density of carnivores, granivores, insectivores, and
omnivores), and (c) population (relative density of individual bird species). Human presence in the high Córdoba Mountains
decreased avian species richness and diversity, and reduced insectivorous relative density, but we did not detect significant
effects on granivores, omnivores, and carnivores. At the population level, 6 of 28 species were negatively affected by human
visitation; four of these species are of conservation concern. Our results show negative responses to recreationists at multiple
levels (e.g., reductions in density, displacement of species from highly visited areas), which may be related to spatial and
temporal access to suitable resources, physical disturbance or species-specific tolerance thresholds. Our study area had lower
levels of human visitation relative to other protected areas in the Northern Hemisphere, which raises the issue of whether
this kind of biogeographically isolated habitat may be too fragile to sustain increasing levels of tourism.
KeywordsEndemic species-Guild-Human disturbance-
Mountainous ecosystem-Recreational activities-South America
"A growing number of studies quantify the impact of nonlethal human disturbance on the behavior and reproductive success of animals. Athough many are well designed and analytically sophisticated, most lack a theoretical framework for making predictions and for understanding why particular responses occur. Behavioral ecologists have recently begun to fill this theoretical vacuum by applying economic models of antipredator behavior to disturbance studies. In this emerging paradigm, predation and nonlethal disturbance stimuli create similar trade-offs between avoiding perceived risk and other fitness-enhancing activities, such as feeding, parental care, or mating. A vast literature supports the hypothesis that antipredator behavior has a cost to other activities, and that this trade-off is optimized when investment in antipredator behavior tracks short-term changes in predation risk. Prey have evolved antipredator responses to generalized threatening stimuli, such as loud noises and rapidly approaching objects. Thus, when encountering disturbance stimuli ranging from the dramatic, lowflying helicopter to the quiet wildlife photographer, animal responses are likely to follow the same economic principles used by prey encountering predators. Some authors have argued that, similar to predation risk, disturbance stimuli can indirectly affect fitness and population dynamics via the energetic and lost opportunity costs of risk avoidance. We elaborate on this argument by discussing why, from an evolutionary perspective, disturbance stimuli should be analogous to predation risk. We then consider disturbance effects on the behavior of individuals--vigilance, fleeing, habitat selection, mating displays, and parental investment--as well as indirect effects on populations and communities. A wider application of predation risk theory to disturbance studies should increase the generality of predictions and make mitigation more effective without over-regulating human activities."
Humans have drastically changed much of the world's acoustic background with anthropogenic sounds that are markedly different in pitch and amplitude than sounds in most natural habitats. This novel acoustic background may be detrimental for many species, particularly birds. We evaluated conservation concerns that noise limits bird distributions and reduces nesting success via a natural experiment to isolate the effects of noise from confounding stimuli and to control for the effect of noise on observer detection biases. We show that noise alone reduces nesting species richness and leads to different avian communities. Contrary to expectations, noise indirectly facilitates reproductive success of individuals nesting in noisy areas as a result of the disruption of predator-prey interactions. The higher reproductive success for birds within noisy habitats may be a previously unrecognized factor contributing to the success of urban-adapted species and the loss of birds less tolerant of noise. Additionally, our findings suggest that noise can have cascading consequences for communities through altered species interactions. Given that noise pollution is becoming ubiquitous throughout much of the world, knowledge of species-specific responses to noise and the cumulative effects of these novel acoustics may be crucial to understanding and managing human-altered landscapes.
As human population and resource demands continue to grow, biodiversity conservation has never been more critical. About one-quarter of all mammals are in danger of extinction, and more than half of all mammal populations are in decline. A major priority for conservation science is to understand the ecological traits that predict extinction risk and the interactions among those predictors that make certain species more vulnerable than others. Here, using a new database of nearly 4,500 mammal species, we use decision-tree models to quantify the multiple interacting factors associated with extinction risk. We show that the correlates of extinction risk vary widely across mammals and that there are unique pathways to extinction for species with different lifestyles and combinations of traits. We find that risk is relative and that all kinds of mammals, across all body sizes, can be at risk depending on their specific ecologies. Our results increase the understanding of extinction processes, generate simple rules of thumb that identify species at greatest risk, and highlight the potential of decision-tree analyses to inform conservation efforts.
We challenge three of the underlying principles of CART, a well know approach to the construction of classification and regression trees (CART). Our primary concern is with the penalization strategy employed to prune back an initial, overgrown tree. We reason, based on both intuitive and theoretical arguments, that the pruning rule for classification should be different from that used for regression (unlike CART). We also argue that growing a tree-structured partition that is specifically fitted to the data is unnecessary. Instead, our approach to tree modeling begins with a nonadapted (fixed) dyadic tree structure and partition, much like that underlying multiscale wavelet analysis. We show that dyadic trees provide sufficient flexibility, are easy to construct, and produce near-optimal results when properly pruned. Finally, we advocate the use of a negative log-likelihood measure of empirical risk. This is a more appropriate empirical risk for non-Gaussian regression problems, in contrast to the sum-of-squared errors criterion used in CART regression.
Vocal alarm calls are important to the vigilance and likely the organization of mixed-species flocks, but community-wide studies of alarm calling in flocks are lacking. We investigated which species alarm-call, and the characteristics of their calls, in a large flock system of a Sri Lankan rainforest. We recorded naturally elicited alarm calls during several attacks by Accipiter hawks and while following flocks for 10 h. We then artificially elicited alarms by throwing a stick to the side of the flock, in a total of 70 trials at 30 flock sites. The Orange-billed Babbler (Turdoides rufescens) was the most frequent caller to both the artificial and natural stimuli, followed by the Greater Racket-tailed Drongo (Dicrurus paradiseus). Several other species also called, and multiple species often called to the same stimulus (in 23 trials, and in all of the hawk attacks). The species differed in their rapidity of response and in their sensitivity to different natural stimuli. Calls of the gregarious babbler usually provided a first, unreliable warning of an incoming threat, whereas later calls of other species emphasized the seriousness of the threat. We suggest that birds in mixed-species flocks may be particularly aware of aerial predators for two reasons: (1) a “numbers effect,” whereby nongregarious species are more aware of predators when surrounded by large numbers of other species; and (2) an “information effect,” whereby species differ in the information available in their alarm calls, leading to an accumulation of information in a mixed-species flock.
Llamadas de Alarma en Bandadas Mixtas de Aves en Sri Lanka
The author subjected waterbirds to experimental disturbance on Sanibel Island, Florida. Approaching birds on foot was the most disruptive of the usual activities of refuge visitors. Photographers were most likely to engage in this activity. -from Author
We tested the ability of sound recordings relative to that of point counts to estimate species richness in the Tambopata Reserve in southeast Peru. We tested the effect of two environmental factors (estimated richness and presence of noisy species) and two attributes of species (abundance and foraging height) on estimates of species richness made by point counts and sound recordings. Sound recordings are preferred to point counts when richness is high, as during the dawn chorus, because they allow for repeated listenings. Point counts are more effective than sound recordings at detecting rarely heard species. The presence of noisy species at a station had no effect off the relative ability of the two methods to measure species richness. The foraging height of a species had no effect on its relative detectability by either method. Sound recording was found to be a suitable alternative to point counts for estimating species richness and a preferable alternative under some circumstances.
1. Introduction 2. Estimation 3. Hypothesis testing 4. Graphical exploration of data 5. Correlation and regression 6. Multiple regression and correlation 7. Design and power analysis 8. Comparing groups or treatments - analysis of variance 9. Multifactor analysis of variance 10. Randomized blocks and simple repeated measures: unreplicated two-factor designs 11. Split plot and repeated measures designs: partly nested anovas 12. Analysis of covariance 13. Generalized linear models and logistic regression 14. Analyzing frequencies 15. Introduction to multivariate analyses 16. Multivariate analysis of variance and discriminant analysis 17. Principal components and correspondence analysis 18. Multidimensional scaling and cluster analysis 19. Presentation of results.
Abstract A huge road network with vehicles ramifies across the land, representing a surprising frontier of ecology. Species-rich roadsides are conduits for few species. Roadkills are a premier mortality source, yet except for local spots, rates rarely limit population size. Road avoidance, especially due to traffic noise, has a greater ecological impact. The still-more-important barrier effect subdivides populations, with demographic and probably genetic consequences. Road networks crossing landscapes cause local hydrologic and erosion effects, whereas stream networks and distant valleys receive major peak-flow and sediment impacts. Chemical effects mainly occur near roads. Road networks interrupt horizontal ecological flows, alter landscape spatial pattern, and therefore inhibit important interior species. Thus, road density and network structure are informative landscape ecology assays. Australia has huge road-reserve networks of native vegetation, whereas the Dutch have tunnels and overpasses perforating road barriers to enhance ecological flows. Based on road-effect zones, an estimated 15–20% of the United States is ecologically impacted by roads.
A three year study of Herring Gull (Larus argentatus) reproductive success on four islands in Maine indicated that production of young was controlled by different factors operating on the eggs and chicks. Hatching success was inversely related to the disturbance of colonies by picnickers, which apparently caused the adults to leave their eggs exposed to sufficient solar radiation to addle the eggs. The survival of chicks was lower on islands distant from sources of edible refuse (outer islands) than on islands close to sources of waste (inner islands), regardless of visits by picnickers. The nutrition and growth rates of chicks on inner and outer islands were similar. The attendance of parents on the territories was found to be less on an outer island than on an inner island. It is concluded that differences in parental behavior associated with greater foraging effort were responsible for a higher loss of chicks to predation on the outer islands.
Rynchops niger, nesting in six subcolonies within a tern colony were subjected to either daily or weekly nest checks. Many prelaying adults left subcolonies that were disturbed daily and settled in relatively undisturbed subcolonies; some pairs in these areas deserted nests early in incubation. Nest density, late nesting, hatching success and fledging success were inversely correlated with disturbance. In consequence of disturbance, a few chicks ate younger conspecifics. Low fences placed around groups of nests depressed fledging in areas disturbed weekly, but enhanced it in subcolonies disturbed daily.-from Authors
The diurnal raptor community of a primary rain forest in French Guiana was studied, both around a small isolated village and far from any human settlement. Twenty species were found in large areas of unbroken forest and 6 additional species only near edges and clearings around the village. The comparison between hunted and non-hunted patches of otherwise similar virgin forest showed that even a moderate hunting pressure (i.e., for food by few people) significantly reduces both mean species richness of sample counts and density of most primary forest raptors. The largest species may eventually disappear. Other than regional avifaunas and local anno- tated lists, including birds of prey, I found no
Vocal alarm calls are important to the vigilance and likely the organization of mixed-species flocks, but community-wide studies of alarm calling in flocks are lacking. We investigated which species alarm-call, and the characteristics of their calls, in a large flock system of a Sri Lankan rainforest. We recorded naturally elicited alarm calls during several attacks by Accipiter hawks and while following flocks for 10 h. We then artificially elicited alarms by throwing a stick to the side of the flock, in a total of 70 trials at 30 flock sites. The Orange-billed Babbler (Turdoides rufescens) was the most frequent caller to both the artificial and natural stimuli, followed by the Greater Racket-tailed Drongo (Dicrurus paradiseus). Several other species also called, and multiple species often called to the same stimulus (in 23 trials, and in all of the hawk attacks). The species differed in their rapidity of response and in their sensitivity to different natural stimuli. Calls of the gregarious babbler usually provided a first, unreliable warning of an incoming threat, whereas later calls of other species emphasized the seriousness of the threat. We suggest that birds in mixed-species flocks may be particularly aware of aerial predators for two reasons: (1) a “numbers effect,” whereby nongregarious species are more aware of predators when surrounded by large numbers of other species; and (2) an “information effect,” whereby species differ in the information available in their alarm calls, leading to an accumulation of information in a mixed-species flock.
Increasingly, natural areas are exposed to people who come to view, study or photograph wildlife. In order to develop appropriate management plans for both avian and human use of natural environments it is essential to understand how people affect foraging birds. The foraging behaviour of five species of water-birds at Loxahatchee (Arthur B. Marshall National Wildlife Refuge), part of the Everglades, in Southern Florida was observed, between 1992 and 1994, from a dike that received many visitors. Species examined included common gallinule (Gallinula
chloropus), sora rail (Porzana
carolina), glossy ibis (Plegadis
falcinellus), little blue heron (Egretta
caerulea) and Louisiana heron (E.
tricolor). These birds were observed before people were near, while people were present, and following the departure of people. Variation in feeding behaviour was largely explained by whether people were present, the number of people present, and the amount of noise made by the people. For all species, time devoted to feeding and number of strikes or pecks decreased while people were present. The percentage of time spent foraging and the number of strikes decreased as the noise made by people increased. Birds that were closer to the path flew away from people more often than birds that were further away. Birds usually swam or flew away from the path while people were present.
One of the results of human disturbance at seabird colonies may be the provocation of the typical vertebrate adrenocortical response to stressors, but there have been few studies that demonstrate this. The present study demonstrates that simple human presence at the nest site, without effects of capture or handling, is physiologically stressful for breeding Magellanic penguins (Spheniscus magellanicus) that are not accustomed to seeing humans. It also demonstrates that birds that have been exposed to very high levels of human visitation via tourism do not respond to human presence as a stressor, whereas those exposed to moderate levels of disturbance do not show evidence of habituation over a period of a few years. These results suggest that tourist visits should be concentrated in a small part of breeding colonies, allowing birds nesting in the visitation area to habituate, leaving the remainder of the colony free of disturbance
Ecotourism helps to protect many habitats, but may also have negative impacts on wildlife. We investigated effects of ecotourists on reproductive success of hoatzins (Opisthocomus hoazin) and on hormonal status of their chicks in Amazonian rainforest lakes by comparing birds from undisturbed and from tourist-exposed nests. Hatching success was similar in both groups but chick survival was much lower at tourist-exposed nests than at undisturbed nests. This effect was due to an increased mortality of juveniles prior to fledging whereas small nestlings seemed largely unaffected. Juveniles, but not nestlings, living at tourist-exposed sites had a lower body mass and showed a stronger hormonal response to experimental stress compared to individuals at undisturbed sites. These data suggest that juvenile hoatzins were susceptible to tourist-induced stress which in turn may be responsible for the lower survival. In contrast, adult hoatzins that were incubating had apparently habituated to tourist presence because their flush distances at tourist-exposed nests were 50% lower than at undisturbed sites. Our findings demonstrate that individuals in different life stages show different susceptibilities to tourism. We suggest that even just watching animals during breeding can threaten their survival, but a proper scientific management of off-limit zones and area-specific guidelines for wildlife observation could reduce harmful effects.
1. Traditional understanding of how hunting affects vertebrate populations empha-sizes competitive release and density dependence of vital rates, but more recent thinking has proposed complex non-lethal responses to hunting disturbance and predation risk. Colonial species have been proposed to be more vulnerable than dispersed, solitary species to disturbance and perceived risk from hunting. However, empirical comparisons of density dependence vs. risk disturbance in hunted species are few. 2. To compare density dependence with risk-disturbance effects of hunting on individ-uals and populations of a colonial species, we tested the response of black-tailed prairie dogs Cynomys ludovicianus to shooting in a before–after, treatment–control experi-ment. We subjected five colonies to a pulse of shooting, and compared individual and colony attributes to those of five control colonies, protected from shooting. 3. Surviving prairie dogs increased alert behaviours eightfold and reduced both above-ground activity and time spent foraging by 66%. Changes in behaviour lowered the body condition of surviving adults by 35%. Survivors of shooting, especially juveniles, exhib-ited elevated stress levels; faecal corticosterone concentrations increased by 80% among juveniles. Unexpectedly, overwinter survival rates did not increase in response to reduced prairie dog density. Colonies subjected to shooting experienced reproductive near-collapse the summer after shooting; pregnancy rates declined by 50% and repro-ductive output fell by 82%. 4. Risk-disturbance overwhelmed any possible density-dependent effects of shooting in prairie dogs, which exhibited additive mortality in response to hunting, and reproductive failure 1 year after shooting. Risk-disturbance was the predominant mechanism whereby individuals and colonies were affected by hunting. 5. Synthesis and applications. Because of their coloniality, prairie dogs possess certain life-history traits that predisposed them to be particularly susceptible to hunting-associated disturbances, which had cascading effects on population-level processes. Our findings contradict the general belief that small-bodied mammals quickly rebound from hunting exploitation via compensatory mortality and reproduction. Managers should consider measures to reduce recreational shooting intensity and duration in regions where black-tailed prairie dog colony growth and persistence is desired, yet allow shoot-ing in areas where colonies conflict with landowner interests.
Does ecotourism contribute towards conservation of threatened species and habitats or is it just a marketing ploy of the tourism industry? Using 251 case studies on ecotourism from the literature, I looked at the distribution of case studies over continents, habitats and flagship species types and what factors influenced whether an ecotourism regime was perceived as ecologically sustainable by authors. Over 50% of ecotourism case studies were reported from Africa and Central America. The overall distribution of ecotourism case studies did not reflect vertebrate endemism, nor overall tourism dis-tribution in terms of tourist numbers and receipts. There were significant differences between continents and habitats with regard to the proportion of sustainable case studies: ecotourism is perceived to be less sustainable in South America and Asia, and in island and mountain habitats. The type of flagship species also influenced whether ecotourism was classified as sustainable or not: ecotourism with no flagship species was rarely classified as sustainable while charismatic bird and mammal species were associated with a higher probability of sustainability. In a multivariate analysis, flagship species type and local community involvement were important predictors of sustainability in ecotourism. Detailed a priori planning, local involvement and control measures were perceived by authors of case studies to increase the success of ecotourism in conservation. They also perceived that ecotourism can only be an effective conservation tool under certain conditions. If these are met, the evidence indicates that ecotourism can make a contribution to conservation.
Species richness is a fundamental measurement of community and regional diversity, and it underlies many ecological models and conservation strategies. In spite of its importance, ecologists have not always appreciated the effects of abundance and sampling effort on richness measures and comparisons. We survey a series of common pitfalls in quantifying and comparing taxon richness. These pitfalls can be largely avoided by using accumulation and rarefaction curves, which may be based on either individuals or samples. These taxon sampling curves contain the basic information for valid richness comparisons, including category–subcategory ratios (species-to-genus and species-to-individual ratios). Rarefaction methods – both sample-based and individual-based – allow for meaningful standardization and comparison of datasets. Standardizing data sets by area or sampling effort may produce very different results compared to standardizing by number of individuals collected, and it is not always clear which measure of diversity is more appropriate. Asymptotic richness estimators provide lower-bound estimates for taxon-rich groups such as tropical arthropods, in which observed richness rarely reaches an asymptote, despite intensive sampling. Recent examples of diversity studies of tropical trees, stream invertebrates, and herbaceous plants emphasize the importance of carefully quantifying species richness using taxon sampling curves.
Humans visiting natural areas often disturb wildlife, possibly displacing animals from desirable habitat. To hold ecotourism at acceptable levels refuge managers need to know which species are likely to be affected and which response occurs at different levels of disturbance. Displacement of waterbirds at J. N. “Ding” Darling National Wildlife Refuge, Florida (U.S.A.), by specific human activities was demonstrated experimentally by Klein in 1993. We assessed the extent of this effect of ecotourism on the distribution of 38 species of waterbirds by surveying birds in plots of known distance from a dike along which wildlife tours occurred. Most resident species were less sensitive to disturbance than were migrants. Migrant ducks were most sensitive when they first arrived, mid-October to mid-December, usually remaining more than 80 m from the drive, even at low levels of human visitation. Herons, egrets. Brown Pelicans (Pelecanus occidentalis), and Anhingas (Anhinga anhinga) were most likely to remain close to areas of high human activity. Shorebirds were displaced at intermediate distance and visitation levels. Mottled Ducks (Anas fulvigula) and several of the ardeids seemed to include two groups differing in behavior, one habituated to humans and one sensitive to disturbance. Public education and changes in management practices are needed to reduce disturbance. Guided tours and low-disturbance zones where people stay in their cars could reduce the negative effects of tourists, especially in the fall when migrants arrive. The number of human visitors may have to be reduced or the wildlife drive closed on certain days during the tourist season.
Ecotourism is expected, by the tourism industry and academics, to grow rapidly over the next 20 years. Much has been written about ecotourism, often with missionary zeal, but there is little consensus about its definition. It is argued here that conservationists and protected area managers should adopt a definition of ecotourism which contributes to the maintenance of biodiversity and an appropriate definition is suggested.
Ecotourism is not merely an alternative to mass tourism, nor is it the only alternative. The literature on nature tourism and the environmental impacts of the industry dates back to the late 1970s. Tourism is now the world's largest industry and it has an increasing impact on protected areas. Our understanding of these mechanisms, their ecological impacts and our capacity to manage tourism in protected areas lags behind the growth of tourism to protected areas.
A rapid growth in nature tourism and tourism to protected areas has coincided with a shift in protected area management strategies towards integrated development. Tourism is one means available to protected area managers seeking to increase the economic value of a protected area and to offer sustainable opportunities for economic development to local people.
This paper argues that potentially conflicting commercial, protected area and development interests all contribute to the emergence of ecotourism and have been doing so for many years. Ecotourism needs to be tightly defined if it is to benefit conservation. Protected area managers should consider how they can take control of nature tourism to the parks they manage and convert it into ecotourism for the benefit of conservation and the livelihoods of local people.
Impacts of petroleum activities on birds in the Amazonian forest of Yasun National Park and the Huaorani Territory, Ecuador, were evaluated using data from 32 standardized 1-day surveys of twenty one 2-ha sites, spread out over 90 km, located at four different distances (0, 0.5, 1.5, and 4.5 km) into floristically diverse, primary, terra firme forest (240–320 m elev.), except one that was in 6-year-old secondary forest. Width of deforestation for roads was 25 m. The 263 species, identified via sight, sound, and mist-netting (4 nets) between 5:45 and 13:30 on days without heavy or constant rain, were grouped into 14 foraging guilds. Discriminant Function Analysis achieved complete separation of the 10 surveys adjacent to roads from the 22 surveys > 0.3 km into the forest, based on species richness per guild. Terrestrial insectivores contributed by far the most (76%) to this separation, and were the only guild to show a significant difference in the average number of species registered between the 6-edge sites and the 15 interior sites (Mann–Whitney U = 4, P = 0.001). Machinery noise seems to particularly affect this guild.
A huge road network with vehicles ramifies across the land, representing a surprising frontier of ecology. Species-rich roadsides are conduits for few species. Roadkills are a premier mortality source, yet except for local spots, rates rarely limit population size. Road avoidance, especially due to traffic noise, has a greater ecological impact. The still-more-important barrier effect subdivides populations, with demographic and probably genetic consequences. Road networks crossing landscapes cause local hydrologic and erosion effects, whereas stream networks and distant valleys receive major peak-flow and sediment impacts. Chemical effects mainly occur near roads. Road networks interrupt horizontal ecological flows, alter landscape spatial pattern, and therefore inhibit important interior species. Thus, road density and network structure are informative landscape ecology assays. Australia has huge road-reserve networks of native vegetation, whereas the Dutch have tunnels and overpasses perforating road barriers to enhance ecological flows. Based on road-effect zones, an estimated 15-20% of the United States is ecologically impacted by roads.
The costs of singing in birds are poorly understood. One potential type of cost is a metabolic cost of singing. Previous studies have measured short-term changes in oxygen consumption associated with bouts of vocalizations, with equivocal results. In this study, I used an alternative approach to measuring the metabolic cost of singing, by measuring overnight loss of body mass, in male common nightingales, Luscinia megarhynchos, singing at night at different rates. Nightingales were shown not to forage at night. They reached a higher mass at dusk prior to singing more at night, and lost more mass overnight when dusk mass and overnight song rate were high. These results show that singing at night is associated with increased overnight consumption of body reserves, which represents a significant metabolic cost of singing at night. However, the correlation between dusk mass and overnight song rate makes it impossible to determine whether these costs arise from the energetic costs of the singing itself, or from the metabolic costs of the additional body reserves laid down at dusk on nights when song rate was high. There are also likely to be costs associated with accumulating and carrying these extra body reserves during daylight, as well as other potential costs of singing such as an increased risk of predation. These results are consistent with those models of signalling in biology that predict or assume that honest signals are costly. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.
In studies of bird song, experimental designs and statistical analyses are often inappropriate for the hypotheses being tested. Frequently, only one playback or tutor stimulus is used to test a number of subjects, and the repeated samples of that single replicate are then analysed statistically as though the samples themselves were replicates. Proper experimental design demands that both the population of subjects and the ‘population’ of song stimuli be sampled adequately. Several designs commonly used for playback or tutoring experiments are illustrated, and changes in design are suggested that would increase the number of independent samples and would thus improve the reliability and external validity (i.e. generalizability) of the experimental work.
Birds were surveyed within four zones defined along a gradient of decreasing impact by the petroleum industry and small-scale agriculture in the moist tropical forest of the Cuyabeno Wildlife Production Reserve in northeastern Ecuador. A total of 12 3-day surveys were conducted at nine sites, divided among the four zones, which consisted of a coffee plantation on the edge of a large deforested area, and three primary forest zones at approximately 0, 1500, and 3200 m from the deforested area (0, 200, and 1000 m from small clearings; 200, 2000, and > 3500 m from roads). All sites were located on the same types of soil and terrain, and the vegetation of all forested sites was physiognomically similar. The most outstanding difference in bird species composition across zones was the reduced number of insectivores in areas of greater human impact (p=0·03). Interior forest insectivore species were significantly more likely to be absent from impacted forests (and non-forest habitats) than were non-insectivores (p=0·000004), and this tendency was also present in the results of other studies of tropical forest birds. These results underscore the need to take insectivores, as well as other particularly sensitive groups, into special consideration within conservation strategies if intact faunas are to be preserved.
Avian diversity in the anthropogenic forests of Tambo-pata, Peru. MSc dissertation Multiple eco-logical pathways to extinction in mammals
- M Champoux
- California
- A Davidson
- M Hamilton
- A Boyer
- G And
- Ceballos
CHAMPOUX, M. 2008. Avian diversity in the anthropogenic forests of Tambo-pata, Peru. MSc dissertation, Stanford University, California. DAVIDSON, A., M. HAMILTON, A. BOYER, AND G. CEBALLOS. 2009. Multiple eco-logical pathways to extinction in mammals. Proc. Natl. Acad. Sci. U.S.A. 106: 10702–10705.
Habits of the crimson-crested woodpecker in Panama
- Kilham
KILHAM, L. 1972. Habits of the crimson-crested woodpecker in Panama. Wilson
Bull. 84: 28-47.
Birds of four neotropical forests
- J Karr
- S Robinson
- J Black
- R Bierregaard
KARR, J., S. ROBINSON, J. BLACK, AND R. BIERREGAARD. 1990. Birds of four neotropical forests. In A. Gentry (Ed.). Four neotropical rain forests, pp.
237-269. Yale University Press, New Haven, Connecticut.
Experimental design and data analysis for biologists R: A language and environment for statistical computing. R Foundation for Statistical Computing The empty forest
- G Quinn
- M And
- Uk R Keough
- Development
- Team
QUINN, G., AND M. KEOUGH. 2002. Experimental design and data analysis for biologists. Cambridge University Press, Cambridge, UK. R DEVELOPMENT CORE TEAM. 2009. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. REDFORD, K. 1992. The empty forest. Bioscience 42: 412–422.
Neotropical birds: Ecology and conservation Raptor community structure of a primary rain forest in French Guiana and effect of human hunting pressure
- D Stotz
- J Fitzpatrick
- T Parker
- D And
- Moskovitz
STOTZ, D., J. FITZPATRICK, T. PARKER, AND D. MOSKOVITZ. 1996. Neotropical birds: Ecology and conservation. University of Chicago Press, Chicago, Illinois. THIOLLAY, J. 1985. Raptor community structure of a primary rain forest in French Guiana and effect of human hunting pressure. Raptor Res. 18: 117–122.
Effects of point count duration, time-of-day, and aural stimuli on detectability of migratory and resident bird species in Quintana Roo Monitoring bird populations by point counts Exposure to ecotourism reduces survival and affects stress response in hoatzin chicks (Opistho-comus hoazin)
- J Lynch
- A Mu Llner
- K Linsenmair
- M And
- Wilkelski
LYNCH, J. 1995. Effects of point count duration, time-of-day, and aural stimuli on detectability of migratory and resident bird species in Quintana Roo, Mexico. In C. Ralph, J. Sauer, and S. Droege (Eds.). Monitoring bird populations by point counts, Gen. Tech. Report PSW-GTR-149. Pa-cific Southwest Research Station, Forest Service, pp. 1–6. US Depart-ment of Agriculture, Albany, California. MU LLNER, A., K. LINSENMAIR, AND M. WILKELSKI. 2004. Exposure to ecotourism reduces survival and affects stress response in hoatzin chicks (Opistho-comus hoazin). Biol. Conserv. 118: 549–558.
R: A language and environment for statistical computing. R Foundation for Statistical Computing
- R Development
- Team
R DEVELOPMENT CORE TEAM. 2009. R: A language and environment for
statistical computing. R Foundation for Statistical Computing, Vienna,
Austria.
Birds of four neotropical forests Four neotropical rain forests
- S Robinson
- J Black
- And R Bierregaard
KARR, J., S. ROBINSON, J. BLACK, AND R. BIERREGAARD. 1990. Birds of four neotropical forests. In A. Gentry (Ed.). Four neotropical rain forests, pp.
237–269. Yale University Press, New Haven, Connecticut.