The Role of Zoos in Monitoring Urban Biodiversity

Biodiversity conservation in large cities is crucial, as it supports the preservation of nature and enhances the quality of life for urban residents. Zoos play a significant role in this effort by serving as research centers that gather valuable data on species’ behavior and ecological requirements. This research helps to better understand the effects of urbanization on biodiversity. Beyond providing safe habitats for wildlife, zoos also function as educational institutions and offer vital green spaces that support the conservation of local species. In doing so, they raise public awareness about the importance of protecting biodiversity.Various studies are conducted in Zagreb to collect data on species and develop measures for their protection and conservation.

As part of this project, two studies were conducted:

Project Title: Nesting Pairs of Hooded Crows (Corvus cornix) in the City of Zagreb
Authors: Dr. Luka Jurinović, M.Sc. Biology; Louie Taylor
Collaborators: Sanjin Hadžalić, Dario Starić
Project Duration: April 2018
Status: Completed
Species: Hooded Crow (Corvus cornix)
IUCN Red List Status: Least Concern (LC)
Croatian Red List Status: Least Concern (LC)

The hooded crow, a familiar resident of urban environments, is among the most abundant nesting bird species in Zagreb. Its adaptability and opportunistic feeding behaviour play a key role in its successful survival. Hooded crows typically nest in open areas with tall trees, such as parks and forest edges. Their breeding season spans from late March to mid-June.

This study focused on counting nesting pairs of hooded crows in Zagreb and found a 27.67% increase in their numbers over the past ten years. Data on their abundance is available in the Bird Atlas of Zagreb (Kralj et al., 2015), which divides the city into one-kilometer quadrants and compiles records from 2003 to 2015. Building on this foundation, the present study revisited quadrants that were surveyed a decade or more ago to assess long-term population trends.

In April 2018, active nests were recorded across 32 quadrants. The results revealed notable increases in several areas,particularly in the Dubrava-Čulinečka and Srednjaci quadrants, indicating the adaptability of hooded crows in urban environments.

Authors: Dr. Luka Jurinović, M.Sc. Biology; Louie Taylor
Project Duration: March 2018
Status: Completed
Species: Grey Heron (Ardea cinerea)
IUCN Red List Status: Least Concern (LC)
Croatian Red List Status: Least Concern (LC)

The Grey Heron is a distinctive bird commonly found in wet urban environments, such as parks and riverbanks. This species typically nests high in trees, often forming colonies. In Croatia, the Grey Heron population is on the rise, with over 3,000 breeding pairs currently recorded. More than 60 heron colonies exist across the country, the largest of which is located in Maksimir Park.

On March 28, 2018, a survey of Grey Heron nests was carried out at the Zagreb Zoo. Using a truck-mounted crane with a maximum reach of 22 meters, researchers recorded a total of 26 nests across 14 trees. Unfortunately, due to technical limitations and unfavorable weather conditions, some nests could not be accessed for detailed monitoring. A follow-up survey conducted on May 17, 2018, aimed at ringing the chicks, also faced similar constraints, leaving many nests inaccessible.

Summary:

Research on urban biodiversity in Zagreb highlights the vital role zoos play in monitoring and conserving local wildlife. Serving as both research centers and educational institutions, zoos gather valuable data on species behavior and ecological requirements—information that is crucial for understanding the effects of urbanization on biodiversity. Two studies in particular examined population trends of the hooded crow and the grey heron, revealing significant increases in nesting pairs. These findings emphasize the growing importance of urban habitats for these species.