# Intensity of Nest Defense of White‐Winged Choughs ( Corcorax melanoramphos ) in Urban Versus Natural Habitats

## TL;DR

White-winged choughs in urban areas spend more time defending their nests due to higher predator presence, showing how urbanization affects bird behavior.

## Contribution

This study provides empirical evidence that urbanization increases nest defense intensity in white-winged choughs due to higher predator abundance.

## Key findings

- Urban areas have a significantly greater abundance of avian nest predators compared to natural habitats.
- Nest defense intensity is significantly higher in urban-breeding white-winged choughs.
- Nest defense intensity does not increase with the age of the brood, contrary to predictions.

## Abstract

Nesting birds face significant risks of predation, prompting parents to invest in nest defense. However, not all environments are the same, and parental investment may vary across different environments. Urbanization often leads to habitat changes and an increase in generalist nest predators, potentially driving a higher risk of reproductive failure for birds. This may require urban‐breeding birds to invest more time and energy in nest defense, in addition to balancing other essential activities, such as incubation, foraging, and feeding their young. Here, we assess the impact of urbanization on nest defense by white‐winged choughs (
Corcorax melanorhamphos
). We predicted that (1) urban habitats have a greater abundance of nest predators compared to natural habitats, and that (2) nest defense would correspondingly be higher in urban‐breeding white‐winged choughs. We also predicted that (3) nest defense in the white‐winged choughs would increase with the age of the brood, in accordance with the nest defense theory, irrespective of their habitat. Our results confirm a significantly greater abundance of avian nest predators in urban areas, and that nest defense is significantly higher in urban groups compared to groups in natural habitats. However, we found no significant increase in nest defense with the age of the brood. Our study confirms that the increase in nest predator abundance can cause urban birds to face different trade‐offs, and have to invest more in nest defense. This reflects one effect of urbanization on the composition and behavior of urban wildlife.

Urbanization changes various conditions for birds to raise their young. Urban areas often have more predators, which forces parents to spend more time and energy protecting their nests. However, this can be difficult because they also need to forage and perform other activities. We studied white‐winged choughs and found that those living in urban areas invested more to keep their nests safe. This shows how urbanization can affect the behavior and survival of birds.