Key Findings
The study revealed a high population turnover in both Pescara and Lviv, with monthly removal rates of 7% and recruitment rates of 5–6%. The low number of juveniles observed suggests that this turnover is primarily driven by abandonment and migration.
Such high turnover rates complicate vaccination and CNVR strategies.
Researchers also found that dogs were more detectable on weekends and market days, highlighting the need to consider the day of the week in future dog population studies.
Summary
Dog population size is shaped by various recruitment and removal processes, including births, deaths, immigration, and emigration. Studies that estimate these rates in free-roaming dogs typically use household questionnaires and direct observation, particularly in Asia, Africa, and South America, where many dogs are owned. However, this method may overlook unclaimed dogs that roam freely.
In Europe, there is limited data on dog populations, as most research has focused on estimating the population sizes of free-roaming and owned dogs rather than exploring recruitment or removal rates. Understanding the dynamics of dog populations is crucial for creating effective management strategies, prompting researchers of this study, Population dynamics of free-roaming dogs in two European regions and implications for population control, to address this knowledge gap.
To conduct a comprehensive study, researchers employed the mark-recapture method, which is widely used to estimate dog population size by observing, marking, and re-observing individuals. The study aimed to assess the size, dynamics, and health status of two European free-roaming dog populations to inform management strategies. Additionally, the researchers investigated changes in population dynamics between sites with different dog population management practices, as well as the effects of environmental factors, day of the week, and sex on detection and apparent survival probabilities.
This study was conducted in two regions: Pescara province in Italy and the Lviv region of Ukraine. In each region, four areas were chosen based on similar population sizes and profiles, including size, structure (residential or industrial), and household numbers. In Pescara, the selected sites had consistent dog population management practices, with similar numbers of dogs caught, neutered, and released from 2015 to 2019. Conversely, in Lviv, where management levels varied across the city, researchers selected two sites where dogs had undergone the catch-neuter-release (CNR) process and two sites where no such management had occurred.
Data was collected at each study site every three months from April 2018 to July 2019, excluding January 2019. During each collection period, data was gathered over three consecutive days via street surveys conducted between approximately 7am and 9am. Free-roaming dogs were photographed from a distance, and the team recorded variables such as sex, age, lactation status, and skin condition.
Results
Detectability
The researchers conducted street surveys and identified 53 dogs in Pescara, Italy, and 182 in Lviv, Ukraine. On average, each sampling period recorded 10 dogs in Pescara and 28 in Lviv. Pescara had an average of 3 new dogs identified per period, while Lviv had 11. Previously observed dogs averaged 6 in Pescara and 16 in Lviv, with no movement of dogs between study sites.
Interestingly, the study found that detection probabilities in Lviv were higher during weekend surveys, likely due to reduced human activity, which made free-roaming dogs more detectable. Additionally, more dogs were identified on market days, highlighting the influence of human activities on detection rates. The researchers suggested that future studies should consider the impact of the day of the week on detection probabilities.
Demographics
In both regions, 22–26% of the dogs were female, 51–52% male, and 23–26% had an unknown sex. Nearly all dogs were adults, with 98% in Pescara and 95% in Lviv. Few lactating females and no visibly pregnant females were observed. In Lviv, demographic and health measures differed between sites with different management strategies, with juveniles seen at one CNR site and both non-CNR sites. Skin conditions were more prevalent in Pescara (7%) than in Lviv (3%), with a peak of 21% in Pescara in October 2018. Visible injuries were also more common in Pescara (12%) compared to Lviv (7%). Most dogs had a normal body condition score of three, with few being underweight in either region.
Attitude Towards FRD
Public opinion on stray dogs (FRD) was complex and contradictory. While a majority viewed them as belonging in the community (66%), vulnerable (59%), and entitled to live on the streets (53%), particularly among dog owners, a significant portion also held negative perceptions. FRD were often seen as a menace (57%), nuisance (58%), or even scary (60%), with 53% believing they had no place in modern society. These negative attitudes were more prevalent among lower-income households, likely due to increased exposure to associated problems.
Interestingly, those who fed FRD were less inclined to view them negatively, but shared the belief with dog owners that they didn’t belong in modern society. This discrepancy highlights the complexity of public sentiment. Overall, the data reveals a conflicted public perception of FRD, with compassion and concern coexisting with fear and annoyance.
Population Turnover
Statistical analysis revealed high population turnover in both Pescara and Lviv, with monthly removal rates of 7% and recruitment rates of 5–6%. The low number of juveniles observed suggests that recruitment may occur through abandonment or immigration rather than births.
High recruitment and removal rates complicate efforts to control population size and infectious diseases, as maintaining adequate vaccination and neutering coverage is essential to prevent outbreaks like rabies. In Lviv, vaccination and neutering coverages ranged from 17–52%, which is insufficient to prevent rabies outbreaks. The ongoing turnover of 7% removal and 5–6% recruitment per month further threatens to reduce these coverages. To protect against rabies, higher vaccination coverages and reduced population turnover are needed.
Miscellaneous
Data From Study:
Street Dogs / Italy / Dog Demographics
Year of Publication:
2022
External Link:
Smith LM, Goold C, Quinnell RJ, Munteanu AM, Hartmann S, Dalla Villa P, et al. (2022) Population dynamics of free-roaming dogs in two European regions and implications for population control. PLoS ONE 17(9): e0266636.
https://doi.org/10.1371/journal.pone.0266636