Assessing mammal population densities in response to urbanization using camera trap distance sampling

Area of Science:

• Urban Ecology
• Wildlife Population Dynamics
• Mammalian Ecology

Background:

• Environmental filtering significantly influences animal abundance and distribution during urbanization.
• Limited understanding exists regarding urbanization's specific effects on terrestrial mammal population densities.
• Urbanization presents unique challenges and opportunities for both invasive and indigenous species.

Purpose of the Study:

• To compare the population densities of invasive (dogs, cats) and indigenous (Siberian weasels, Amur hedgehogs, Tolai hares) mammals in response to urbanization.
• To investigate the relationship between mammal densities and varying levels of urbanization using advanced statistical models.
• To assess the influence of urban-related and nature-related variables on mammal population densities.

Main Methods:

• Camera trap distance sampling (CTDS) was employed for wildlife surveys in a rural-urban landscape (Tianjin, China).
• Generalized additive mixed models (GAMMs) were utilized to analyze species-specific responses to urbanization levels.
• Population densities were estimated for five mammal species: dogs, cats, Siberian weasels, Amur hedgehogs, and Tolai hares.

Main Results:

• Amur hedgehogs showed the highest abundance (6.73 individuals/km²), followed by Tolai hares (2.22 individuals/km²) and Siberian weasels (2.15 individuals/km²).
• Invasive dogs (2.63 individuals/km²) and cats (2.15 individuals/km²) exhibited similar density estimations.
• Densities of cats, Siberian weasels, and Amur hedgehogs increased with urbanization levels. Dog and cat densities were influenced solely by urban factors, while weasel and hedgehog densities were affected by both urban and natural variables.

Conclusions:

• CTDS is a viable and promising method for wildlife assessments in diverse rural-urban environments.
• Urban wildlife management strategies must integrate the impacts of both urban development and natural elements.
• Fine-scale analysis of green space habitats is crucial for understanding and managing urban wildlife populations effectively.