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. 2021 Jul 6;11(1):13931.
doi: 10.1038/s41598-021-92844-2.

Colonization of Warsaw by the red fox Vulpes vulpes in the years 1976-2019

Mateusz Jackowiak  1   2 , Jakub Gryz  3 , Karolina Jasińska  4 , Michał Brach  5 , Leszek Bolibok  6 , Piotr Kowal  4 , Dagny Krauze-Gryz  7
Affiliations

Colonization of Warsaw by the red fox Vulpes vulpes in the years 1976-2019

Mateusz Jackowiak et al. Sci Rep. .

Abstract

The red fox is one of the most adaptable carnivores inhabiting cities. The aim of our study was to describe the process of Warsaw colonization by the red fox. We focused on: (1) the fox distribution in Warsaw on the basis of presence-absence data (2005-2012) over a grid of 1 × 1 km2, (2) the process of settlement in 29 green areas (study periods 1976-1978, 2004-2012, and 2016-2019) in relation to habitat type, and (3) temporal and spatial patterns of the red fox incidents (1998-2015) reported by Warsaw citizens. We found out that: (1) the red fox penetrated the whole city (i.e. its presence was confirmed in all squares of the grid), (2) 21% of the green areas were colonized in 1976-1978 but 93% in 2016-2019. Forests and riparian habitats were occupied more frequently than parks and cemeteries in 1976-1978 with no difference in the further years; (3) the probability of the fox incidents increased over years, was higher in June-October, on working days, and around noon, and with the share of discontinuous urban fabric in the buffers around incident locations. Nevertheless, the incidents only partially reflect population abundance trends and activity patterns of the species, so should be treated cautiously.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Distribution of green areas and other habitats in Warsaw. The Palace of Culture and Science, assumed as the most central point of the city is marked.
Figure 2
Figure 2
The grid of squares searched for presence signs to assess red fox distribution in Warsaw in 2005–2012. The Palace of Culture and Science, assumed as the most central point of the city is marked.
Figure 3
Figure 3
Presence of the red fox as confirmed by snow tracking in 29 randomly selected green areas in Warsaw in the three study periods (data for 1976–1978 after Goszczyński J., unpbl.).
Figure 4
Figure 4
Proportion of green areas occupied by the red fox as confirmed by snow tracking, attributed to four habitat types in Warsaw, in subsequent study periods: (a) 1976–1978 (Goszczyński J., unpbl. data), (b) 2004–2012 and (c) 2016–2019. A full circle indicates actual proportion and an empty circle indicates expected proportion of colonized areas attributed to a certain habitat type, bars depict lower and upper bound of the confidence interval.
Figure 5
Figure 5
Probability of the red fox incident (a) during a year and (b) in the whole research period with comparison between weekdays and weekends as based on the reports on fox incidents in the city area (1998–2015), delivered by the Municipal Forests—Warsaw.
Figure 6
Figure 6
Modelled number of the red fox incidents per minute during the day as based on the reports on the red fox incidents in the city area (1998–2015), delivered by the Municipal Forests—Warsaw.
Figure 7
Figure 7
Expected probability of the red fox incidents as based on the reports (1998–2015), delivered by the Municipal Forests—Warsaw, in relation to distance to (a) the Vistula river (an ecological corridor), (b) share of forest, (c) share of agricultural areas, and (d) share of wetlands within 100 m radius around location of red fox incident. Explanatory variables that were significant in the logistic regression model (see Table 2) are shown.
Figure 8
Figure 8
Probability of the red fox incident as based on the reports (1998–2015), delivered by the Municipal Forests—Warsaw, in relation to distance to (a) the Vistula river, (b) the city centre and (c) share of discontinuous urban fabric within 1500 m radius around location of red fox incident. Explanatory variables that were significant in the logistic regression model (see Table 2) are shown.
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