NATURA SLOVENIAE 24(1): 43-45 Prejeto / Received: 8. 2. 2022 
FIELD NOTE Sprejeto / Accepted: 13. 6. 2022 
 
Biotehniška fakulteta Univerze v Ljubljani in Nacionalni inštitut za biologijo, Ljubljana, 2022 
The first record of the 
Cumberland slider Trachemys 
scripta troostii (Thunberg & 
Schoepff, 1792) (Testudines: 
Emydidae) in Slovenia 
 
Prva najdba okrasne gizdavke 
Trachemys scripta troostii (Thunberg & 
Schoepff, 1792) (Testudines: Emydidae) 
v Sloveniji 
 
Tomaž REMŽGAR, Fisheries Research Institute of 
Slovenia, Spodnje Gameljne 61a,  
SI-1211 Ljubljana – Šmartno, Slovenia;  
E-mail: tomaz.remzgar@zzrs.si 
 
The pond slider (Trachemys scripta) is a freshwater 
turtle species native to the South-Eastern part of 
USA, but has also been introduced to many other 
countries around the world through pet trade 
(Escoriza et al. 2021b). Due to its colourful 
appearance, it has been the most numerous turtle 
species in pet shops for decades with millions of 
hatchlings reared every year on turtle farms. Their 
owners are eventually releasing many turtles to the 
nature, after overgrowing their confinements or 
simply becoming too difficult to keep (Cadi & Joly 
2004). Pond sliders established populations in 
wetlands around the world (Espindola et al. 2019) 
and have a negative effect on indigenous turtles 
(Cadi & Joly 2004, Escoriza et al. 2021a). Today, 
pond sliders are banned from sale in many countries 
worldwide. In Slovenia, the sale of this turtle species 
was banned in 2017, after it was proven that it 
reproduced (Vamberger et al. 2012) and established 
vital populations in the country (Standfuss et al. 
2016).  
 
In their natural range, the pond slider has three 
accepted and one putative subspecies that differ in 
colouration of the neck and plastron and the shape 
and texture of the carapace (Praschag et al. 2017, 
Vamberger et al. 2020). The nominal subspecies, 
the yellow-eared slider (T. s. scripta) is 
distinguishable by a vertical yellow S-shaped stripe 
behind its eye, a yellow coloured plastron with only 
a few small black markings and a less elongated and 
more domed carapace (Praschag et al. 2017, Ernst 
& Lovich 2009). The commonest subspecies in pet 
trade was the red-eared slider (T. s. elegans), 
having a red horizontal stripe on its neck and a 
yellow plastron with large black spots on each scale 
(Praschag et al. 2017, Ernst & Lovich 2009). 
Cumberland slider (T. s. troostii) generally 
resembles T. s. elegans, but is distinguishable by its 
narrower horizontal neck stripe that starts with pale 
green or yellow colour and fades into dark red 
towards the end of the neck. Their plastron is yellow 
with medium-sized black spots on each scale (Carr 
1937, Ernst & Jett 1969, Parham et al. 2020, 
Vamberger et al. 2020). The fourth subspecies, the 
Western slider, has only recently been proposed 
based on a DNA study of the T. scripta species 
(Vamberger et al. 2020). It was considered a 
distinct morph of the T. s. elegans and some 
authors considered it the result of hybridization with 
adjacent taxa. The Western slider has, in general, 
more elongated head than T. s. elegans, the red 
neck stripe is smaller and often split into two 
patches and the black spots on the plastron scales 
are the largest of all T. scripta subspecies. The 
status of these alleged subspecies remains to be 
resolved in further studies. Considering the species 
natural ranges, the Cumberland slider has the 
smallest natural range. It inhabits only the upper 
reaches of the Cumberland and Tennessee Rivers, 
its range overlapping with T. s. scripta and  
T. s. elegans only in the southernmost part of its 
range (Ernst & Lovich 2009, Vamberger et al. 2020). 
 
Despite the recent ban on selling pond sliders in 
Slovenia, this species has already spread through 
most of the country and established several large 
reproducing populations (Standfuss et al. 2016). 
One of such population inhabits the waterways and 
wetlands in the Vipava Valley in Western Slovenia. 
One of the goals of the VIPava project (a nature 
conservation project, financed by EU Cohesion 
funds, link: https://www.projektvipava.si/), led by 
The Fisheries Research Institute of Slovenia, is to 
improve the habitat conditions for the highly 
protected European pond turtle (Emys orbicularis), 
the species included in the Appendix 2 of the 
Habitats Directive (OJ EC 1992). This native 
freshwater turtle has small fragmented populations 
in the Vipava Valley, concentrated in and around 
small ponds, channels and oxbow lakes close to the 
Vipava River (Vamberger et al. 2015). Removing 
pond sliders from waterbodies close to the Vipava 
River is one of the actions to improve the habitat for 
the European pond turtle. Invasive turtles currently 
represent one of the major ecological threats to the 
indigenous European pond turtle by competing for 
sources of food and most importantly basking 
places (Cadi & Joly 2004). Since the pond sliders 
44 Tomaž REMŽGAR: The first record of the Cumberland slider Trachemys scripta trostii in Slovenia / FIELD NOTE 
NATURA SLOVENIAE 24(1): 43-45 
grow bigger and are much more active and 
aggressive, they can easily compete for the best 
basking places in the water bodies, at least under 
controlled conditions in the laboratory (Cadi & Joly 
2004). 
 
During our fieldwork carried out in 2017, we focused 
on catching and removing pond sliders from water 
bodies, known to be inhabited by the European 
pond turtles, or larger ponds, where significant 
numbers of reproducing pond sliders had been 
detected (Standfuss et al. 2016). The turtles were 
caught with fishing pods for catching crayfish and 
with basking traps. In 20. 9. 2019, we sampled the 
Vogršček water reservoir in the central Vipava 
Valley. Among a total of 16 turtles caught (15  
T. s. elegans, 1 T. s. elegans × T. s. scripta), one 
individual of the captured turtles generally 
resembled the T. s. troostii subspecies (Fig. 1). The 
individual was an adult female with carapace length 
of 186 mm and a weight of 1001 grams. The neck 
stripe was thin and yellow to pale green in colour 
that faded into dark green, without any shades of 
red or orange. The carapace was light green with a 
pattern of lighter and darker green stripes and 
curves, and was not domed as in T. s. scripta. The 
surface of the carapace was rough. The plastron 
was yellow with medium sized black markings on 
each scale. The colouration of the front legs was 
typical of the T. s. troostii subspecies with broad 
yellow parallel stripes (Fig. 1). The age of the 
individual was estimated at 18–20 years by counting 
the growth rings on its plastron. It is uncertain 
whether it had been released from captivity or 
hatched in the wild, but judging by the size of the 
turtle, its general good condition and lack of any 
damage or scars it was most likely the former case. 
 
Despite no DNA sample was collected, the typical 
morphological characters enabled reliable 
subspecies identification. It is unclear how the  
T. s. troostii subspecies came to Slovenia, since it is 
the least known and attractive of the four pond 
slider subspecies, and there is no record of it ever 
being sold in pet shops in the country. One possible 
explanation is that it was imported on a personal 
request or even came to Slovenia from the 
neighbouring Italy.
 
 
Figure 1. Photos of head (top) and plastron (below) of a 
T. s. troostii individual, caught in Vogršček in September 
2019. Notice the thin yellow to pale-green neck stripe 
and medium sized black spots on plastron (Photo: ZZRS). 
Slika 1. Fotografiji glave (zgoraj) in plastrona (spodaj) 
osebka T. s. troostii, ujetega septembra 2019 v 
Vogrščku. Opazne so tanka rumena do bledo zelena 
proga na vratu ter srednje velike črne lise na luskah 
plastrona (Foto: ZZRS). 
 
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