Natural History Sciences. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano, 10 (1): 87-90, 2023 DOI: 10.4081/nhs.2023.647

Short communication

Arboreal behaviour of the wood mouse Apodemus sylvaticus (Rodentia: 
Muridae): a study in the Venetian plain

Alessandro Nardotto

Via Guizze 55/3, Villorba (TV), Italia.
E-mail: info.wildlifeservices@gmail.com

© 2023 Alessandro Nardotto

Received for publication: 21 September 2022
Accepted for publication: 18 November 2022
Online publication: 20 April 2023

Abstract - The arboreal activity of the wood mouse is known, 
but mostly based on anecdotal evidence or single records. This study 
reports on field observations carried out systematically during an indi-
rect survey conducted in the Venetian plain using hair tubes positioned 
at different heights in the shrub layer. The research confirmed that in 
the study area the wood mouse moves not only at ground level, but at 
also a few meters above the ground reaching heights up to 2.30 m (1.54 
m on average).

Keywords: Arboreal behaviour, hair tube, small mammals.

Riassunto - Comportamento arboricolo del topo selvatico Apode-
mus sylvaticus (Rodentia: Muridae): uno studio nella pianura veneta.

L’attività arboricola del topo selvatico è nota, ma basata soprattutto 
su testimonianze aneddotiche o singole osservazioni. Il presente studio 
riporta osservazioni di campo effettuate sistematicamente durante 
un’indagine indiretta condotta nella pianura veneta, mediante l’utilizzo 
di hair tube posizionati a varie altezze nello strato arbustivo. Lo studio 
ha confermato che il topo selvatico si muove non solo a livello del 
suolo, ma anche ad alcuni metri dal terreno, raggiungendo altezze fino 
a 2,30 m nell’area di studio (1,54 m in media).

Parole chiave: Comportamento arboricolo, hair tube, piccoli mam-
miferi.

INTRODUCTION
The wood mouse Apodemus sylvaticus (Linnaeus 

1758) is a small rodent widely spread throughout Europe, 
from the Iberian Peninsula to Western Russia, reaching 
to the north Sweden, Norway and even Iceland (Amori 
et al., 2008). In Italy, the species populates most of the 
peninsula and some islands like Sicily, Sardinia, Elba, 
Giglio, Capri and Pantelleria (Amori, 1993; Capizzi & 
Santini, 2007), thanks to its broad capacity to adapt to 
different ecological conditions (Amori et al., 2008). The 
species is present throughout the Veneto region, from sea 
level up to quite high elevations, even beyond 2000 m 

(Bon, 2017). Although most of the species’ activities are 
carried out at ground level (Jennings, 1975; Flowerded, 
1991), the wood mouse also has a marked aptitude for 
climbing, reaching up to 3-4 meters in height on shrubs 
(Montgomery, 1980; Gurnell, 1985). Although this be-
haviour has been frequently reported, arboreality of the 
species has been little investigated and this information 
often remains anecdotal (Buesching et al., 2008). As a se-
condary result of a monitoring of small mammals carried 
out in a protected area of the Veneto plain, it was possible 
to collect quantitative data on this little-studied behaviour 
in a systematic way.

MATERIALS AND METHODS
Study area

The present study was conducted in the Regional 
Natural Park of the River Sile, sited between the loca-
lities of Canizzano (TV) and Quinto di Treviso (TV) 
(45°38’47.8”N, 12°11’35.6”E). This is a riparian area 
adjacent to the River Sile and close to the Treviso airport, 
consisting of mixed-species hedges with Rubus ulmifo-
lius Schott, Cornus sp. and to a lesser extent Morus alba 
L., Corylus avellana L. and other shrub and tree species, 
and woods with Ulmus minor Mill., Alnus glutinosa (L.) 
Gaertn., Quercus robur L., Robinia pseudoacacia L. 
Reedbeds are also present in some areas.

Data collection and analysis
Data were collected during a monitoring survey con-

ducted with hair tubes (Pocock & Jennings, 2006; Chiron 
et al., 2018) and targeted at the hazel dormouse Muscardi-
nus avellanarius (Linnaeus 1758). In this case, the choice 
fell on tubes 20 cm long and 3.5 cm in diameter, in order 
to facilitate entry only to target species and those of simi-
lar size, as has already been successfully experimented 
in other studies (Tioli & Zocca, 2010). In particular, 30 
tubes arranged in two transects of 15 tubes each were tied 
at a distance of 5-10 m apart on the branches of trees and 
shrubs at a height ranging from 100 cm to about 250 cm, 
depending on the shrubs. Horizontal branches have been 
favoured to enhance the stability of the hair tubes. The 
placement height of each hair tube was then recorded 
rounding the measurement down to the nearest ten cen-



88

timetres. The hair tubes were left in place for about two 
and a half months, from 25 May to 2 August 2022, and 
were checked periodically (5 times) every two weeks to 
collect any samples, replace the double-sided tape and put 
the tubes back in place. The collected samples were first 
removed from the double-sided tape and then cleaned of 
impurities by immersion first in acetone and then in water. 
The hair was then identified under an optical microscope 
at 100× and 400× magnification through the diagnostic 
microstructures of the cuticle (outermost layer, formed by 
the overlapping of transparent keratin scales) and the me-
dulla (inner part, formed by dead cells).

Identification was performed by visual comparison 
with figures in specialist texts (Debrot et al., 1982; Tee-
rink, 1991; Paolucci & Bon, 2022).

In order to obtain a statistical description of the arboreal 
behaviour of the wood mouse in relation to the height at-
tained in the shrub layer, a weighted average of the heights 
of the frequented hair tubes was calculated, taking into ac-
count the height of placement and the number of positi-
ve controls per hair tube (i.e. those in which hairs of the 
species are present). In addition, the range (minimum and 
maximum heights) of occurrence of the wood mouse in the 
arboreal environment is reported. The mean for each con-
trol and the confidence intervals were also calculated. The 
chi-square test was performed to check whether there were 
differences between the various sampling sessions. All sta-
tistical analyses were performed in the R environment (R 
Core Team, 2022).

RESULTS
During the survey, only wood mouse samples we-

re collected. The average placement height of the hair 
tubes frequented by the wood mouse is 1.54 m ± 0.36 
(S.D.). The hair tube positioned at the height of 2.30 m 
was frequented 4 times, the highest recorded height. In-
stead, the lowest tube used was located at 1.10 m. With 
the exception of the first sampling session, in which no 
hair samples of the species were found, in the subsequent 
ones the average height of the frequented tubes is around 
1.50 m in height, not showing significant differences 
between one sampling session and another (χ2= 2.1204, 
p=0.9992).

DISCUSSION
The information reported in this work testifies and 

confirms the arboreal habits of the wood mouse (Bue-
sching et al., 2008). Although the arrangement of the tu-
bes may have probably influenced the results obtained, it 
can be said that the species appears to move skilfully from 
the ground level up to the height of 2.30 m. The findings 
are consistent with the observations reported in other 
European contexts (Gurnell, 1985), even if they do not 
reach the record height of 23.37 m exceptionally recor-
ded in Poland for A. flavicollis (Melchior 1834), a species 
that shows similar arboreal behaviour (Borowski, 1962; 
Montgomery, 1980). The reason for this behaviour seems 
to be attributable to a combination of factors such as the 

SHORT COMMUNICATION

Fig. 1 - Averages and confidence intervals of the heights of the hair tubes used by the wood mouse during the sampling sessions. / Valori 
medi e relativi intervalli di confidenza delle altezze degli hair tube utilizzati dal topo selvatico durante le sessioni di campionamento.



89NAT U R A L HISTORY SCIENCES. ATTI SOC. IT. SCI. NAT. M USEO CI V. STOR. NAT. MILA NO, 10 (1): 87-90, 2023

search for additional food sources and the possibility of 
escaping predators (Buesching et al., 2008). Furthermo-
re, the presence of the species also in the shrub layer can 
represent a disturbing factor for the hazel dormouse, as 
the two species can potentially compete for resources. In 
Germany, for example, it was observed that the absence 
(or the presence at low densities) of A. sylvaticus and A. 
flavicollis has a positive effect on the abundance of the 
hazel dormouse (Villing & Horst, 2021). Given the Com-
munity interest of the hazel dormouse (Habitats Directive 
92/43/CEE), in-depth investigations into the ecological 
implications of the coexistence of this two rodent species 
in this study area are recommended.

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Fig. 2 - Medulla (above) and cuticle (below) of wood mouse hair seen under an optical microscope. / Midollo (sopra) e cuticola (sotto) 
di peli di topo selvatico visti al microscopio ottico.



90

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