Esteban Fernández-Juricic

Human-wildlife interactions in urbanized landscapes, protected areas, and airports

Background

Urban sprawl (about 50% of the human population now lives in cities and suburban areas) has increased the chances of humans interacting with wildlife under different scenarios. For instance, urbanization increases fragmentation effects, which reduces the suitability of remaining habitat fragments for wildlife. Recreational activities are increasing in areas of conservation concern (e.g., hot-spots), which may increase human disturbance effects, reducing the ability of wildlife to use and persist in protected areas. Airports provide habitat for many bird species; however, the chances of bird-aircraft collision increase substantially, which causes economic losses to the aviation industry (approximately 1.2 Billion US$ annually) and the possibility of mortal accidents.

The resource use-disturbance trade-off hypothesis may account for human-wildlife interactions by assessing the relationship between the frequency of human visitation (number of pedestrians per unit time per unit area) and the frequency of resource use (breeding, foraging, roosting, etc.) at local scales. For instance, consider a certain patch with resources within a protected area. The frequency of human visitation may be low enough during the day to allow birds to make use of that patch in the intervals between consecutive visitors walking by the patch. However, when the frequency of human visitation becomes more frequent, individuals would not be able to use the resources in that patch because the intervals between visitors would be too short. If this situation is widespread across most of a protected area, then individuals may face a sheer decrease in the temporal and spatial availability of resources, thereby reducing the suitability and carrying capacity of a protected area.

The tolerance of different bird species to humans appears to be related to the distance at which they detect disturbance. The implication is that to reduce the rate of human-wildlife interactions different strategies may be necessary depending on the type of human activity. Within protected areas, it is important to reduce the chances of wildlife detecting recreationists to minimize disturbance; however, in airports, it is better to increase the chances of wildlife detecting aircraft to enhance avoidance behaviors and minimize bird-aircraft collisions. 

Goals

1- To test the resource use-disturbance trade-off hypothesis in species with different life histories, since management recommendations could change radically according to the species tolerance to disturbance.

2- To understand the physiological, environmental, and social factors affecting inter-specific differences in detection windows (areas surrounding an individual where the probabilities of detecting tourists increase) to better estimate buffer areas to protect wildlife.  

3- To determine suitable management strategies that promote co-existence between wildlife and humans in protected areas and airports based on theoretical models that consider the resource use-disturbance trade-off hypothesis as the mechanism of interaction, detection windows of species with different degrees of visual perception, and the spatial and temporal responses of wildlife to human disturbance.

Model species

Various bird species, including common and endangered ones.

Methodological approaches

Main contributions (for more details see my papers)

(I) Fragmentation negatively affects social processes, such as the formation of mono- and mixed-species flocks in forest fragments of different size and degree of isolation (Ardea 88: 235-242; Ecoscience 9: 450-458).

(II) Human disturbance can interact with fragmentation causing synergistic effects at the landscape scale (Condor 102:247-255).

(III) Managing human-wildlife interactions in protected areas requires proximate and ultimate studies. First, we should understand the proximate behavioral mechanisms by which different species respond to recreational activities, and the population level consequences of these interactions. Second, this multi-species level approach should also identify the natural and life-history factors explaining the variability in tolerance to human disturbance and proneness to extinction across species (Conservation Biology 18: 1175-1177).  

(IV) I put forward a mechanism to predict human-wildlife interactions based on the relationships between the frequency of human visitation and the frequency of resource use (e.g., foraging, breeding, roosting, etc.) by wildlife (resource-use disturbance trade-off hypothesis). This hypothesis argues that thresholds in the intensity and pattern (both spatial and temporal) of human activity exist below which animals can continue to meet their feeding and breeding requirements, and above which the availability of resources to animals is diminished, thereby reducing the carrying capacity and the suitability of disturbed areas for wildlife (Condor 102:247-255; Oecologia 131:269-278).

(V) The resource-use disturbance trade-off hypothesis has been successfully tested through observational and manipulative approaches in birds (Condor 105: 316-326) and amphibians (Biological Conservation 123: 1-9).

(VI) We developed new spatial and temporal indicators of wildlife tolerance to human disturbance, such as detection distance and time to resume pre-disturbance activities, that help estimate buffer areas that better represent the ecological requirements of different species (Environmental Conservation 28:263-269; Biological Conservation 117: 407-416; Biological Conservation 125: 225-235).

(VII) In a comprehensive theoretical and comparative study, we found that detection distance is the main factor affecting bird inter-specific responses to human disturbance. The implication of this finding is that the same levels of human visitation may affect species in different ways depending on the ability of each species to detect visually the presence of people. Detection distances are related to body mass, controlling for phylogenetic effects; thus, larger species tend to have greater detection distances, and as a result are more sensitive to recreational activities (Journal of Applied Ecology 42: 943-953).

(VIII) In collaboration with other researchers, I have developed a spatially-explicit individually-based simulation that predicts habitat selection and population abundance of species with different degrees of tolerance to human disturbance (Journal of Applied Ecology 42: 943-953). This simulation allows the user to manipulate both the spatial and temporal distribution of recreational activities (e.g., number and arrangement of pathways, visitation load per pathway, etc.), and the ecology and behavior of different species through cellular-automata approaches. Furthermore, the output of the simulation is habitat-specific because it uses GIS technology, and species-specific because the simulation uses certain biological parameters that need to be estimated from the target species through standardized field protocols. This simulation is intended as one of many tools to help managers assess some ecological consequences of variations in recreational activity levels.