# Spatial and Temporal Trends in the Invasion Dynamics of the Ring-Necked Parakeet (Psittacula krameri) in the Urban Complex of Thessaloniki, Greece

## TL;DR

This study tracks the growing population of ring-necked parakeets in Thessaloniki, Greece, showing they thrive in urban green areas and are expanding rapidly.

## Contribution

The first detailed study on the invasion dynamics of ring-necked parakeets in the urban complex of Thessaloniki.

## Key findings

- Parakeet presence is strongly linked to dense urban areas and green spaces.
- The population grew by 64% from 2024 to 2025, with a 10% increase in occupied sites.
- Thessaloniki supports a large and expanding ring-necked parakeet population.

## Abstract

The ring-necked parakeet is a charismatic parrot that has become one of the most successful invasive bird species in Europe. Originally from Africa and Asia, its presence in Greece counts more than four decades. However, until now, no one has studied how its population is changing or what makes it thrive in Greek cities. In this study, we recorded the presence and abundance of parakeets across the urban complex of Thessaloniki to understand where they live, how many there are, and how their presence and numbers are changing. We found that their presence is mostly associated with dense urban areas and green spaces. In addition, their population showed strong short-term growth, increasing by an estimated 64% from 2024 to 2025. Our results suggest that Thessaloniki supports a large and expanding parakeet population. Keeping track of their numbers in the future is important, since their spread could affect native wildlife.

Invasive alien species pose a major threat to global biodiversity, especially within Europe. Understanding their spatial and temporal dynamics is essential for effective management planning and implementation. The ring-necked parakeet (Psittacula krameri, hereafter RNP) has been established in Greece for over four decades, yet its invasion dynamics remain unstudied despite pilling evidence of ecological impacts. During 2024 and 2025, we conducted repeated transect surveys across 99 1 km2 grid squares within the urban complex of Thessaloniki to assess environmental factors influencing occupancy and abundance, and to estimate RNP population trends. Dynamic occupancy and N-mixture models revealed that both the presence and abundance of RNP were positively associated with the proportion of dense urban fabric and urban green areas. The proportion of occupied sites increased by more than 10% between survey years (2024–2025), while the estimated population growth rate for this interval was 1.64, signaling a substantial short-term increase. Our findings provide the first detailed evidence of an established and growing RNP population within the urban complex of Thessaloniki, Greece. Continued monitoring and research on ecological impacts are essential, while any management actions should be developed with public engagement to ensure social acceptance and long-term effectiveness.