scholarly journals Small Prey Animal Habitat Use in Landscapes of Fear: Effects of Predator Presence and Human Activity Along an Urban Disturbance Gradient

2021 ◽  
Vol 9 ◽  
Author(s):  
Loren L. Fardell ◽  
Catherine E. M. Nano ◽  
Chris R. Pavey ◽  
Christopher R. Dickman
Keyword(s):  
Human Activity ◽  
Human Disturbance ◽  
Perceived Risk ◽  
Urban Environments ◽  
Domestic Cat ◽  
Natural Conditions ◽  
Human Disturbances ◽  
Small Prey ◽  
Disturbance Gradient ◽  
Giving Up Density

Human activity can impose additional stressors to wildlife, both directly and indirectly, including through the introduction of predators and influences on native predators. As urban and adjacent environments are becoming increasingly valuable habitat for wildlife, it is important to understand how susceptible taxa, like small prey animals, persist in urban environments under such additional stressors. Here, in order to determine how small prey animals’ foraging patterns change in response to habitat components and distances to predators and human disturbances, we used filmed giving-up density (GUD) trials under natural conditions along an urban disturbance gradient. We then ran further GUD trials with the addition of experimentally introduced stressors of: the odors of domestic cat (Felis catus)/red fox (Vulpes vulpes) as predator cues, light and sound as human disturbance cues, and their combinations. Small mammals were mostly observed foraging in the GUD trials, and to a lesser degree birds. Animals responded to proximity to predators and human disturbances when foraging under natural conditions, and used habitat components differently based on these distances. Along the urban disturbance gradient situation-specific responses were evident and differed under natural conditions compared to additional stressor conditions. The combined predator with human disturbance treatments resulted in responses of higher perceived risk at environments further from houses. Animals at the urban-edge environment foraged more across the whole site under the additional stressor conditions, but under natural conditions perceived less risk when foraging near predators and further from human disturbance (houses). Contrastingly, at the environments further from houses, foraging near human disturbance (paths/roads) when close to a predator was perceived as lower risk, but when foraging under introduced stressor conditions these disturbances were perceived as high risk. We propose that sensory and behavioral mechanisms, and stress exposure best explain our findings. Our results indicate that habitat components could be managed to reduce the impacts of high predation pressure and human activity in disturbed environments.

scholarly journals Contrasting changes in reproductive success of birds in cities with reduced and increased human disturbance during the COVID-19 lockdown

2021 ◽  
Author(s):  
Gábor Seress ◽  
Krisztina Sándor ◽  
Ernő Vincze ◽  
Ivett Pipoly ◽  
Boglárka Bukor ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Human Activity ◽  
Human Disturbance ◽  
Human Mobility ◽  
Parus Major ◽  
Urban Environments ◽  
Urban Habitat ◽  
Forest Site ◽  
Spatial And Temporal Scales ◽  
Induced Changes

Abstract The ubiquitous activity of humans is a fundamental feature of urban environments affecting local wildlife in several ways. Testing the influence of human disturbance would ideally need experimental approach, however, in cities, this is challenging at relevant spatial and temporal scales. Thus, to better understand the ecological effects of human activity, we exploited the opportunity that the city-wide lockdowns due to the COVID-19 pandemic provided during the spring of 2020. We assessed changes in reproductive success of great tits (Parus major) at two urban habitats affected strikingly differently by the ‘anthropause’ and at an unaffected forest site. Although anecdotic observations suggested that urban wildlife may benefit from reduced human mobility during the lockdown, our results do not support this. First, at one of our urban sites, the strongly (-44%) reduced human disturbance in 2020 (compared to a long-term reference period) did not increase birds’ reproductive output relative to the forest habitat where human disturbance was low in all years. Second, in the other urban habitat, recreational human activity considerably increased (+ 40%) during the lockdown and this was associated with strongly reduced nestling body size compared to the pre-COVID reference year. Analyses on meteorological conditions and the lockdown-induced changes in air pollution suggest that these factors are not likely to explain our results. Our study supports that intensified human disturbance can have adverse fitness consequences in urban populations. It also highlights that a few months of ‘anthropause’ is not enough to counterweight the detrimental impacts of urbanization on local wildlife populations.

scholarly journals Contrasting effects of the COVID-19 lockdown on urban birds’ reproductive success in two cities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gábor Seress ◽  
Krisztina Sándor ◽  
Ernő Vincze ◽  
Ivett Pipoly ◽  
Boglárka Bukor ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Human Activity ◽  
Human Disturbance ◽  
Human Mobility ◽  
Parus Major ◽  
Urban Environments ◽  
Urban Habitat ◽  
Forest Site ◽  
Spatial And Temporal Scales ◽  
Induced Changes

AbstractThe ubiquitous activity of humans is a fundamental feature of urban environments affecting local wildlife in several ways. Testing the influence of human disturbance would ideally need experimental approach, however, in cities, this is challenging at relevant spatial and temporal scales. Thus, to better understand the ecological effects of human activity, we exploited the opportunity that the city-wide lockdowns due to the COVID-19 pandemic provided during the spring of 2020. We assessed changes in reproductive success of great tits (Parus major) at two urban habitats affected strikingly differently by the ‘anthropause’, and at an unaffected forest site. Our results do not support that urban great tits benefited from reduced human mobility during the lockdown. First, at one of our urban sites, the strongly (− 44%) reduced human disturbance in 2020 (compared to a long-term reference period) did not increase birds’ reproductive output relative to the forest habitat where human disturbance was low in all years. Second, in the other urban habitat, recreational human activity considerably increased (+ 40%) during the lockdown and this was associated with strongly reduced nestling body size compared to the pre-COVID reference year. Analyses of other environmental factors (meteorological conditions, lockdown-induced changes in air pollution) suggest that these are not likely to explain our results. Our study supports that intensified human disturbance can have adverse fitness consequences in urban populations. It also highlights that a few months of ‘anthropause’ is not enough to counterweight the detrimental impacts of urbanization on local wildlife populations.

Changes in escape behaviour of black iguanas (Ctenosaura similis) over an anthropogenic disturbance gradient

Behaviour ◽  
2021 ◽  
pp. 1-21
Author(s):  
Pooja Panwar ◽  
Pilar Angélica Gómez-Ruiz ◽  
Matthew N. Zipple ◽  
Luis Sandoval
Keyword(s):  
Human Disturbance ◽  
Protected Area ◽  
Anthropogenic Disturbance ◽  
Escape Behaviour ◽  
Human Presence ◽  
Disturbed Areas ◽  
Disturbance Gradient ◽  
The Impact ◽  
Ctenosaura Similis ◽  
Flight Initiation

Abstract Studies on the impact of human activity on animal behaviour are critical for understanding the extent to which humans affect ecological dynamics. Previous studies have found that human presence alters antipredator behaviours, which can be measured by flight initiation distance (FID). We investigated escape behaviour of 96 black iguanas (Ctenosaura similis) across a gradient of human disturbance in six sites inside a protected area in Costa Rica. We used a field experiment to test for effect of human disturbance on FID. We found that individuals from higher disturbance sites had shorter FIDs, meaning that black iguanas from disturbed areas allow closer approaches. This finding is consistent with the prediction that some animals become more habituated to human presence as the degree of human disturbance increases. We propose that black iguanas’ ability to alter their behaviour in response to humans’ presence could make them especially adept at invading new environments.

Landscape Influences on Stream Habitats and Biological Assemblages

2006 ◽  
Keyword(s):  
Total Phosphorus ◽  
Human Disturbance ◽  
Regional Scale ◽  
Vertebrate Species ◽  
Catchment Scale ◽  
Human Disturbances ◽  
Disturbed Condition ◽  
Small Streams ◽  
Definition Of ◽  
Assemblage Metrics

<em>Abstract.</em>—At broad scales, the types and intensities of human disturbances to ecosystems vary along natural gradients. Biological assemblages also vary with natural and human disturbance gradients. We defined least-disturbed conditions for a set of water chemistry, catchment, and site-scale indicators of disturbance, for 835 Environmental Monitoring and Assessment Program sites in the Mountains, Xeric, and Plains regions of 12 conterminous western United States. For each disturbance indicator, the definition of least-disturbed was adjusted by the sites’ locations on the primary natural gradients. For example, the least-disturbed condition for phosphorus in eastern Plains streams allowed up to 100 µg/L total phosphorus, while in western Plains streams, less than 30 µg/L total phosphorus was required. Sites were scored by the number of times they met the least-disturbed condition for all disturbance indicators. We also applied this process to score for most-disturbed condition. The importance of disturbance types varied regionally and along natural gradients. For example, catchment-scale disturbance measures did not distinguish between least- and most-disturbed sites for small streams at higher elevations, but were important for larger streams and at lower elevations. We examined regional-scale patterns in aquatic vertebrate species and assemblage metrics, and macrobenthos assemblage metrics at least- and most-disturbed sites. Most-disturbed sites in the Mountains and Xeric regions had higher proportions of nonnative and tolerant vertebrates and noninsect macrobenthos, and lower proportions of Ephemeroptera, Plecoptera, and Trichoptera individuals and taxa than did the least-disturbed sites. The Plains region has been extensively used by humans and showed less contrast between disturbance classes for most of these measures.

scholarly journals Using Count Data Models to Predict Epiphytic Bryophyte Recruitment in Schima superba Gardn. et Champ. Plantations in Urban Forests

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 174
Author(s):  
Dexian Zhao ◽  
Zhenkai Sun ◽  
Cheng Wang ◽  
Zezhou Hao ◽  
Baoqiang Sun ◽  
...  
Keyword(s):  
Count Data ◽  
Human Disturbance ◽  
Negative Binomial ◽  
Urban Environments ◽  
Tree Planting ◽  
Count Data Models ◽  
Urban Tree ◽  
Schima Superba ◽  
Hurdle Models ◽  
Positive Effects

Epiphytic bryophytes are known to perform essential ecosystem functions, but their sensitivity to environmental quality and change makes their survival and development vulnerable to global changes, especially habitat loss in urban environments. Fortunately, extensive urban tree planting programs worldwide have had a positive effect on the colonization and development of epiphytic bryophytes. However, how epiphytic bryophytes occur and grow on planted trees remain poorly known, especially in urban environments. In the present study, we surveyed the distribution of epiphytic bryophytes on tree trunks in a Schima superba Gardn. et Champ. urban plantation and then developed count data models, including tree characteristics, stand characteristics, human disturbance, terrain factors, and microclimate to predict the drivers on epiphytic bryophyte recruitment. Different counting models (Poisson, Negative binomial, Zero-inflated Poisson, Zero-inflated negative binomial, Hurdle-Poisson, Hurdle-negative binomial) were compared for a data analysis to account for the zero-inflated data structure. Our results show that (i) the shaded side and base of tree trunks were the preferred locations for bryophytes to colonize in urban plantations, (ii) both hurdle models performed well in modeling epiphytic bryophyte recruitment, and (iii) both hurdle models showed that the tree height, diameter at breast height (DBH), leaf area index (LAI), and altitude (ALT) promoted the occurrence of epiphytic bryophytes, but the height under branch and interference intensity of human activities opposed the occurrence of epiphytic bryophytes. Specifically, DBH and LAI had positive effects on the species richness recruitment count; similarly, DBH and ALT had positive effects on the abundance recruitment count, but slope had a negative effect. To promote the occurrence and growth of epiphytic bryophytes in urban tree planting programs, we suggest that managers regulate suitable habitats by cultivating and protecting large trees, promoting canopy closure, and controlling human disturbance.

Predation on tadpoles by hatchlings of the freshwater turtle

1999 ◽  
Vol 20 (2) ◽  
pp. 173-183 ◽  
Author(s):  
Mark-Oliver Rödel
Keyword(s):  
At Risk ◽  
Water Column ◽  
Body Shape ◽  
Water Levels ◽  
Freshwater Turtle ◽  
Natural Conditions ◽  
Small Prey ◽  
Regional Influence ◽  
Reduced Water

AbstractExperiments with Pelomedusa subrufa, a widespread African freshwater turtle, showed that this species consumed large quantities of tadpoles. Tadpoles preyed upon, comprised between 0.05 and 21.55% of the turtle's biomass. This demonstrated that Pelomedusa subrufa was neither gape limited nor did it ignore very small prey. Tadpoles with an ovoid body shape (Hemisus marmoratus, Hyperolius nitidulus, Ptychadena maccarthyensis), which shared, under natural conditions, the pond bottom microhabitat with the turtles, were more threatened than the robust tall-finned Kassina tadpoles that lived in the middle of the water column. The translucent, slow swimming Phrynomantis microps tadpole occurred in larger ponds and preferred the upper water column in deeper parts of the pond. This species was especially at risk in ponds with reduced water levels. Turtles, in contrast to fish or dragonfly larvae, are capable of migrating to other ponds. They therefore might have a profound regional influence on tadpole communities in ephemeral savanna ponds.

Anthropogenic influence on an urban colony of the little penguin Eudyptula minor

2008 ◽  
Vol 59 (7) ◽  
pp. 647 ◽  
Author(s):  
Darren Giling ◽  
Richard D. Reina ◽  
Zoe Hogg
Keyword(s):  
Human Disturbance ◽  
Urban Environments ◽  
Breeding Sites ◽  
Global Context ◽  
Nest Sites ◽  
Accessible Region ◽  
Minor Population ◽  
Restricted Region ◽  
Nesting Activity ◽  
Little Penguin

Native animals exploit resources in cities and inhabit anthropogenic structures worldwide. One example of this is the little penguin, Eudyptula minor, population nesting between boulders on the St Kilda breakwater in Melbourne. This population is attracted by safe hiding places, a lack of predators and the presence of prey. However, living close to urbanisation poses many threats to the colony, including boating, lighting, noise and human visitation. We investigated the effects of human disturbance by comparing the number of penguins and breeding sites in the publicly accessible region with those in the restricted region of the breakwater. Penguins and nest sites were not equally distributed along the breakwater, with the mean number of birds and nest sites present per 20-m section in the restricted region significantly greater (typically double) than the number in the publicly accessible region. Although the penguins show a clear preference to nest in the restricted region of the breakwater, their continued presence in the publicly accessible region when nest sites are not limiting indicates that human disturbance is not incompatible with some nesting activity. In a global context these results illustrate some of the benefits and costs to animals that use anthropogenically altered habitats and urban environments.

scholarly journals Influence of Human Disturbance on the Abundance of Himalayan Pheasant (Aves, Galliformes) in the Temperate Forest of Western Himalaya, India

2011 ◽  
Vol 45 (6) ◽  
pp. e-40-e-47 ◽  
Author(s):  
V. Jolli ◽  
M. Pandit
Keyword(s):  
Human Disturbance ◽  
Temperate Forest ◽  
Large Scale ◽  
Anthropogenic Activities ◽  
Western Himalaya ◽  
Field Studies ◽  
Line Transect ◽  
Hydroelectric Development ◽  
Disturbance Gradient ◽  
Construction Activity

Influence of Human Disturbance on the Abundance of Himalayan Pheasant (Aves, Galliformes) in the Temperate Forest of Western Himalaya, India We conducted field studies in the Jiwa valley (Indian Himalayas) to examine the influence of human disturbance on Himalayan pheasants. We used the "call count" and "line transect" methods to estimate the abundance of pheasants in Jiwa valley. A human disturbance gradient defined by human population, agriculture activity, forest wood collection, grazing, vehicle, use of heavy machines, human settlements, dumping ground, and blasting was prepared. We assessed the pheasant numbers under two conditions (1) a decline in the gradient of human activity during two consecutive years (2009-2010) (2) in the presence of hydroelectric development activities. The numbers of koklass pheasants, Himalayan monal, cheer pheasant and Western tragopan declined significantly with anthropogenic activities. During spring 2010, hydroelectric construction activity was temporarily suspended in Manjhan adit, and a positive response was noted in terms of an increase in the pheasant numbers near the site. The response of pheasants to human disturbance has inferred that large scale development can lead to decline of Himalayan pheasant in Himalayan region.

Avian assemblage structure and domestic cat densities in urban environments

2007 ◽  
Vol 14 (2) ◽  
pp. 387-399 ◽  
Author(s):  
Victoria Sims ◽  
Karl L. Evans ◽  
Stuart E. Newson ◽  
Jamie A. Tratalos ◽  
Kevin J. Gaston
Keyword(s):  
Urban Environments ◽  
Assemblage Structure ◽  
Domestic Cat

Foraging Response to Risks of Predation and Competition in Artificial Pools

2010 ◽  
Vol 56 (1) ◽  
pp. 9-20 ◽  
Author(s):  
Gil Stav ◽  
Burt P. Kotler ◽  
Leon Blaustein
Keyword(s):  
Perceived Risk ◽  
Foraging Activity ◽  
Left Behind ◽  
Similar Tendency ◽  
Green Toad ◽  
Risk Of Predation ◽  
Giving Up Density ◽  
Culiseta Longiareolata ◽  
The Rich ◽  
Resource Patches

Although ecologists have learned much about the influence of competitors and perceived risk of predation on foraging in terrestrial systems by measuring giving-up density (GUD, the amount of food left behind in a resource patch following exploitation), GUDs have rarely been used in aquatic environments. Here we use foraging activity (proportion foraging) and GUDs to assess the effects that two periphyton consumers and potential competitors, green toad (Bufo viridis) tadpoles and mosquito (Culiseta longiareolata) larvae, have on each other. We also examine the effects of perceived risk of predation imposed by a dragonfly nymph (Anax imperator). To do so, we conducted an artificial pool experiment and developed a food patch appropriate for measuring GUDs for periphyton grazers. MoreCulisetaindividuals foraged in rich food patches than in poor patches.Bufoshowed a similar tendency. FewerBufoforaged in both patch types in the presence of cagedAnax. Culisetashowed a similar tendency. However, in the rich patches, onlyBuforeduced foraging activity when the caged predator was present. BothBufoandCulisetadepleted food patches through exploitation, resulting in lower GUDs. Both competitors together resulted in lower GUDs than did food depletion of each species alone. However, the presence of cagedAnaxhad little or no effects on GUDs. Overall, bothBufoandCulisetarespond to food and safety. They are able to direct foraging effort to richer patches and devote more time to those patches, and they respond to predation risk by choosing whether or not to exploit resource patches.

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