Ecological aspects of Red Squirrel (Sciurus vulgaris) dreys in city parks

Abstract

Modified habitats often pose challenges to native fauna. Red squirrels (Sciurus vulgaris) successfully inhabits territory of the cities. However research on quite abundant red squirrel populations in urban parks of Lithuania was lacking. The investigation was carried out in two city parks (area of Giruliai park 152 ha, Pasakų park forest-31 ha) in Vilnius, Lithuania. Both areas were mainly coniferous, dominated with pine (Pinus sylvestris). Drey (N = 415) counts were done in February and March 2014-2016. Dreys were found in eight tree species. The red squirrels' dreys were mainly built in most widespread tree species: pine (84.8% of all dreys) and birch (8.1%). Most of the found dreys were built on the side branches at the stem (47.7%). 21.8% of the dreys were built on the branches further from the stem, 18.5% on the top branches and 12% in the stem fork-off. Most of the dreys were set in the southern exposition (33.9%). Average number of red squirrels in both parks in 2014-2016 was 0.20±0.01 squirrels/ha, the average number of dreys-0.75±0.05 dreys/ha. The population of urban red squirrels in Vilnius city parks can be regarded as stable and having medium abundance, which is supported by supplementary feeding.

A systematic review into the suitability of urban refugia for the Eurasian red squirrel Sciurus vulgaris

“…peanuts) can also cause nutritional deficiencies, which may have health implications in highly urbanised environments where squirrels may not be able to compensate for such malnutrition if there is limited availability of natural food sources (Thomas et al 2018). Finally, feeders may facilitate the spread of parasites and diseases, such as SQPV, by encouraging interactions both between red squirrels and with grey squirrels (Chantrey et al 2014, Kopij 2014, Stirkė 2019).…”

“…Vieira et al (2015) reported that two red squirrel populations, which had been reintroduced into urban parks, were suffering from long‐term declines due to the poor‐quality habitat. Tree species composition in urban greenspaces is also important for providing suitable nesting sites (Kopij 2009, Stirkė 2019).…”

“…Many of the studies in this review have emphasised the importance of the availability and quality of urban greenspaces for red squirrel populations. For example, it is crucial to manage the tree species composition in urban greenspaces to ensure the availability of natural food sources (Vieira et al 2015, Reher et al 2016, Jokimäki et al 2017) and the provision of suitable nesting sites (Kopij 2009, Stirkė 2019). However, it is difficult to unpick the relative importance of natural and supplemental food sources and habitat quality, as there often tends to be supplemental feeding wherever red squirrels are present in urban areas, as well as the availability of other anthropogenic food sources.…”

“…Red squirrels have been shown to spend more time foraging on the ground when supplemental food is available, which may lead to more encounters with road traffic or predators; red squirrels usually spend 67-90% of their active time foraging for natural food in the canopy, but this is reduced to 50-53% when foraging for supplemental food (Shuttleworth 2001). Reproductive rates are densitydependent, so artificially high population densities can reduce fecundity in some females and therefore decrease breeding success (Kopij 2014, Stirkė 2019). Excessive consumption of supplemental food (e.g.…”

Influences of Weather Conditions, Natural Food Abundance, and the Spacing of Feeders on the Feeding-Table Use by Japanese Squirrels Sciurus lis in a Suburban Forest

“…However, the studies of Eurasian red squirrel have shown that the concentration of several individuals on feeding tables can have negative effects such as inter-individual conflict (Wauters et al 2002), increased predation risk (Shuttleworth 2001), and the spread of disease (Chantrey et al 2014). Consequently, supplemental feeding can decrease breeding success (Kopij 2009; Stirkeė 2019). In fact, we observed predators such as martens and owls via automatic cameras installed on the feeders during the survey and found collars that had previously been attached to squirrels on the ground near the feeders.…”