1 Acorns were good until tannins were found: factors affecting seed-selection
2 in the hazel dormouse (Muscardinus avellanarius)
3 Leonardo Ancillottoa,b, Giulia Sozioa, Alessio Mortellitiac*
4
5 aDepartment of Biology and Biotechnology “Charles Darwin”, University of Rome “La 6 Sapienza”, Viale dell’Università 32, 00185, Rome Italy. 7 b Wildlife Research Unit, Laboratorio di Ecologia Applicata, Dipartimento di Agraria, 8 Università degli Studi di Napoli Federico II, Portici (Napoli), Italy 9 c Fenner School of Environment and Society, Australian Research Council Centre for 10 Environmental Decisions, National Environmental Research Program, The Australian 11 National University, Canberra, ACT 0200. Phone: T: +610261252737 12
13 *corresponding author: [email protected]
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15
16
1
17 Abstract
18 Seed selection by forest rodents is based on several factors such as seed palatability,
19 manipulation time and caloric content. The final result of this decision-making process has
20 critical consequences on seed predation and dispersal, and thus on tree demography.
21 Previous studies on seed selection have mainly focused on non-hibernating terrestrial rodents.
22 Arboreal rodents may be less adapted to cope with seed defences, usually being more
23 frugivorous. Furthermore, hibernating species need to accumulate fat reserves in autumn,
24 which is when acorns are available and may be the only available resource. We selected the
25 hazel dormouse (Muscardinus avellanarius, an arboreal hibernating rodent) as model species
26 for our study and focused on three seeds which are an important constituent of the hazel
27 dormouse diet and which are characterized by different defensive strategies.
28 We here report the results of a series of experiments targeted towards understanding the
29 effects of manipulation time, energy intake and tannin content on seed selection by the hazel
30 dormouse and the effects of such selection on individuals' body condition. Each of these
31 factors was treated separately through a series of coupled food trials. Our results showed a
32 clear order of consumption with first choice biased towards seeds with lower tannin content
33 (Q. pubescens vs Q. cerris) and/or more caloric seeds (C. avellana vs Q. pubescens) despite
34 the higher degree of mechanical protection of the former. Seeds with high levels of tannins
35 led to weight decrease, despite the large amounts of seed mass ingested by dormice. Our
36 results suggest that seed selection by the hazel dormouse is targeted towards maximising fat
37 storage, which is pursued despite the cost of higher manipulation time.
38
39 Keywords: diet; food choice, Gliridae; Quercus; rodents; cafeteria experiments.
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41
42 Introduction
43 Tree seeds (e.g. acorns, seeds of oaks of the Quercus genus) are a fundamental resource for
44 wildlife, especially for forest-dwelling rodents. Rodents have crucial effects on tree
45 demography by contributing to seed predation and dispersal (Hulme, 1998; Velho et al.,
46 2012). Trees need to balance the benefits of dispersal (Steele et al., 2011) with the negative
47 effects of seed loss due to predation (Steele et al., 2005; Zong et al., 2010). As a consequence,
48 many tree species evolved defence mechanisms in order to manipulate rodents’ behaviour and
49 minimize seed predation. Typical seed anti-predatory adaptations consist in harder or thicker
50 pericarps (Zhang and Zhang, 2008), which prolong manipulation time (Jacobs, 1992), and
51 large seed dimensions, which can discourage a rodent to transport the seed (Muñoz and
52 Bonal, 2008). Both these characteristics decrease predation risk by increasing energetic costs
53 for predators. Chemical secondary compounds too can make seeds less palatable, poisonous
54 or at least poorly digestible (Chung-Maccoubrey et al., 1997; Rubino et al., 2012; Shimada
55 and Saitoh, 2003), thus contributing to discourage predation. Acorns in particular are known
56 to have high levels of tannins (Shimada, 2001), a group of polyphenolic molecules which
57 reduce nutrient absorption (Shimada et al., 2006).
58 Previous studies focused on the interactions between rodents and tree seeds have mainly
59 focused on terrestrial or semi-terrestrial (Buesching et al., 2008) rodents (e.g. Apodemus and
60 Mus spp.) whose diet is based on acorns over extended periods and have thus developed
61 several strategies to cope with high levels of tannins (Molinari et al., 2006; Shimada, 2006;
62 Takahashi and Shimada, 2008; Xiao et al., 2008). Little has been done on arboreal rodents
63 (but see Rubino et al., 2012 and Smallwood and Peters, 1986). Arboreal rodents are more
64 capable than terrestrial rodents of exploiting the above-ground availability of fruit (which
65 decays quickly on ground); however, they may still have to rely on acorns for extended
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66 periods (Juškaitis, 2008; Moller, 1983). Furthermore, no previous study has focused on
67 hibernating rodents, i.e. species that need to accumulate fat reserves in autumn, which is
68 when acorns are abundant and may be the only available resource. Arboreal hibernating seed
69 consumers are able to consume acorns before they are available to terrestrial species, and
70 may significantly increase their seed consumption before hibernation; therefore they may
71 influence the interactions between trees and seed predators at the community level (Muñoz et
72 al., 2009; Sunyer et al., 2013).
73 For this study we conducted a series of experiments targeted towards understanding factors
74 influencing seed predation by the hazel dormouse (Muscardinus avellanarius, an arboreal
75 hibernating rodent) and the effects of seed selection on individuals’ body condition. We
76 focused on three seed defensive elements, which we expected to affect foraging decisions by
77 the hazel dormice: thickness of pericarp (influencing manipulation time), nutritional
78 composition (directly influencing energy intake) and chemical defences (i.e. tannin content,
79 influencing palatability, digestibility and thus indirectly affecting final energy intake). For
80 this purpose we selected three seeds characterised by contrasting degrees of these defensive
81 characteristics. Specifically we designed our experiments to ask the following research
82 questions:
83 1) What is the effect of seed mechanical defence on seed manipulation time? Answering
84 this question would allow us to quantify the actual time required by hazel dormice to
85 access the resource. We expected manipulation time to be significantly higher for
86 seeds with thicker pericarps. Time spent handling a seed is a relevant trait in the
87 decision-making process by rodents (Wang et al., 2013), thus a quantitative
88 assessment of manipulation time of different seeds is a basic pre-requisite for
89 understanding the process of seed predation.
90 2) Which species (and consequently which seed traits) are preferred by hazel dormice for
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91 foraging? The ability of rodents to select seeds of different species, e.g. according to
92 their nutritional or chemical content before consuming them is a fundamental factor
93 affecting the rodent-trees interactions (Rosalino et al., 2013). Seed traits such as
94 tannin concentration or pericarp thickness are known to alter seed selection by rodents
95 (Wang et al., 2013; Xiao et al., 2008). As seed biochemical and mechanical defences
96 are subject to a trade-off (Chen et al., 2012), seed predators can specialize to overtake
97 one kind of protection or the other. We thus expected dormice to act a selection
98 towards seeds that maximize energy intake, i.e. seeds with low tannin content, short
99 manipulation time and high caloric content.
100 3) What is the effect of seed selection on the body condition of hazel dormice? Different
101 diets can lead to variation in body conditions in rodents (Shimada and Saitoh, 2003).
102 Seeds with different traits can be unevenly available in woodlands, according to tree
103 species composition, relative abundances and masting events (Focardi et al., 2000;
104 Pons and Pausas, 2007). Assessing how diets based on different seeds affect body
105 condition in rodents, particularly in hibernating species, is an important aspect in
106 understanding the relationships between trees and seed consumers. We expected that
107 seeds selected by dormice would lead to a more efficient fat storage and that a tannin-
108 rich diet lead to a weight decrease.
109 Answering to the three questions listed above will allow us to understand factors affecting
110 foraging decisions by the hazel dormice and contribute to untangling the complex decision-
111 making processes involved in seed predation. Such results may help in providing cues on
112 how to interpret habitat choice, e.g. the different demographic performance of dormice
113 populations in habitat types characterised by different acorn availability (Capizzi et al., 2002;
114 Juškaitis, 2008; Mortelliti et al., 2010; Williams et al., 2013) and thus to improve the accurate
115 parameterisation of distribution modelling (Greaves et al., 2006).
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116 Materials and methods
117 Choice of the target species
118 We chose the hazel dormouse (Muscardinus avellanarius, a strictly arboreal and hibernating
119 rodent) as target species for our study for three reasons: 1) it is a species of conservation
120 concern which is declining in parts of its range due to habitat loss and degradation, thus a
121 deeper understanding of its foraging ecology will help guiding conservation actions such as
122 habitat management and reintroduction programs (Bright and Morris, 1996; Mortelliti et al.,
123 2011) ; 2) the quality of habitat (quality and availability of resources) is a key determinant of
124 its survival and distribution (Mortelliti, 2013). The presence of oaks in fact seems an
125 important factor in determining dormouse presence, at least in the UK, as highlighted by
126 Williams et al. (2013). 3) It has been used as model species for other forest dependent
127 vertebrates due to its life-history and ecological traits (Amici and Battisti, 2009; Bright and
128 Morris, 1996; Greaves et al., 2006; Watts et al., 2010).
129
130 Dormouse housing
131 For the duration of the experiments (6 months) naive captive bred dormice (n=7) were housed
132 singly in 45x40x45(h) cm glass tanks with wire-mesh windows for aeration, and each
133 provided with hay bedding, branches and a wooden nest-box. Water was always available.
134 Tanks were housed in a non-heated room and a large window provided a natural day-night
135 cycle. All dormice had no experience with the target species of acorns or nuts at the start of
136 the experiments, being previously fed with commercial rodent seed-mix and fresh fruit.
137 Due to the conservation status of this species (listed in Annex IV of the Habitat Directive) it
138 was mandatory to keep the number of sampled individuals relatively small, but still
139 comparable to other cafeteria experiments on rodents (Ben-Moshe et al., 2001; Shimada,
140 2001). Required permits for carrying out this research were obtained: permit number 011289
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141 PNM II granted to A.M. by the Ministry of Environment, Rome, Italy.
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143 Seed composition and chemical properties
144 We used hazel nuts (seeds of Corylus avellana), acorns of the downy oak (Quercus
145 pubescens) and Turkish oak (Quercus cerris) as target species for our study. Nutritional
146 characteristics (lipid, protein, carbohydrates and fiber content), total energy intake and
147 secondary compounds (tannins) of the target seed species are shown in Table 1. Acorns used
148 for chemical analyses were harvested in the same woodlands of those used in the behavioural
149 experiments (see further); hazel nuts used for the experiments were of the same cultivar
150 analysed by Xu and Hanna (2011), from which nutritional data were extracted. All seeds were
151 stored in cloth bags in refrigerated room at 8-10°C until they were used for experiments.
152 We selected these two oak species for three reasons: a) they are among the most abundant
153 trees in mixed-deciduous woodlands of Mediterranean Italy (Lookingbill and Zavala, 2000;
154 Pons and Pausas, 2007); b) although can occur syntopically, they are the dominant species of
155 different habitat types (Q. pubescens forests are typical of more coastal and drier habitats
156 whereas Q. cerris forests occur more inland (Mohler, 1990), c) they are the most important
157 contributors to the seed bank biomass in such habitats (Focardi et al., 2000). Differences in
158 the biochemical composition of the acorns of these two species are only evident for the tannin
159 content, which is much higher in Q. cerris acorns (almost double compared to Q. pubescens,
160 Table 1). Hazel nuts (Corylus avellana) are considered as a fundamental resource for dormice
161 (Bright and Morris, 1996; Juškaitis and Baltrūnaitė, 2013). Compared to oak acorns, hazel
162 nuts show much higher calorific content mostly due to higher lipid and protein contents (see
163 Table 1) but are also characterised by tannin content comparable to that of Quercus
164 pubescens.
165 The three target species thus differ in their seed traits (Table 1) such as chemical defences and
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166 pericarp thickness, and thus represent a good combination of traits for evaluating the seed
167 selection decision-making by the hazel dormice.
168
169 EXPERIMENT 1: Manipulation time
170 Ten seeds of Q. cerris, Q. pubescens and C. avellana were offered to dormice, each species
171 separately during different nights, and their nocturnal activity was filmed with a Sony
172 camcorder SR501 with night-shot function (two examples of videos are provided as
173 Supplementary Material).
174 Foraging activity was later analysed by observing the video-recordings adopting “focal
175 subject sampling” (Altmann, 1974) for recording time spent in the different behaviours,
176 distinguishing between 1) seed manipulation, e.g. holding, rotating and chewing the seed
177 shell, and 2) seed consumption, i.e. fragmenting and ingesting the kernel.
178 For each video session, we recorded individual dormouse identity and acorn initial weight.
179 We did not include in the analyses the time during which the dormouse was recorded in non-
180 foraging activities such as moving, grooming, alert and vocalising (Ancillotto et al., 2014).
181 Each individual dormouse was tested for 2-4 nights for each seed species.
182 Seed mass and calories ingested (i.e. energy intake) by dormice per time-unit during each test
183 were calculated as grams or calories / total manipulation time. Only video-recordings during
184 which the focal dormouse completely consumed the acorn were used in the analyses.
185
186 EXPERIMENT 2: Cafeteria tests
187 The seeds of the three species were offered to captive dormice in a series of cafeteria choice
188 tests (Krebs, 1999); during each test, an equal number of acorns of two species was offered in
189 different petri dishes (5 seeds in each dish) positioned inside dormice's cages at around 8 pm.
190 We tested pairs of species as follows: Q. cerris vs Q. pubescens, Q. pubescens vs C. avellana.
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191 Acorns of both species in each test were selected in order to have approximately the same
192 dimensions and weight (5.2±0.2 gr for Q.cerris vs Q. pubescens tests, 5.8±0.2 gr for Q.
193 pubescens vs C. avellana tests). After the start of the test, we checked the acorns twice, at 11
194 pm and 8 am respectively, recording the number of acorns of each species that were totally or
195 partially (¼, ½ or ¾) consumed. Assignment of acorn species to dishes was randomized at
196 each check interval to avoid dormice selecting dish position instead of seed species. We stress
197 that this experiment was the first to be conducted, so that food choices reflect true
198 preferences, not being influenced by habituation of experimental individuals to a type of seed
199 (Experiment 1).
200
201 EXPERIMENT 3: Monospecific diet effects
202 Acorns of the same species were available ad libitum to each dormouse and were replaced
203 with new ones once every four days for the entire duration of the experiment (24 days for
204 each treatment); total seed weight was recorded before and after each check in order to
205 quantify the effective mass consumed by dormice. Weight and conditions of each dormouse
206 were recorded once every 4 days. Each dormouse was tested consecutively with three
207 different treatments (C. avellana, Q. cerris and Q. pubescens) and the order of treatment
208 administration to each individual was randomized.
209
210 Data analysis
211 For experiments 1 and 3 we adopted repeated-measures ANOVAs testing the effects of seed
212 species on manipulation times, mass and calories ingested in the time-unit (grams/min;
213 Kcal/min) during each test (experiment 1) as well as on individual weight variation, mass of
214 seed consumed and ingested calories (experiment 3). Data were tested for normality with
215 Shapiro-Wilk tests. We used Holm's post-hoc tests to assess significant differences among
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216 treatments. For experiment 2 we adopted exact binomial tests on choice data upon first
217 species tasted and seed species most consumed. Results were considered significant when p <
218 0.05; all tests were run in R 2.13.2 (R Core Team, 2005).
219
220 Results
221 EXPERIMENT 1: Manipulation time
222 We obtained 45 complete video-recordings of dormice consuming seeds (C. avellana n = 15,
223 Q. pubescens n = 15, Q. cerris n = 15; see video S1 and S2 in Supplementary Material). The
224 following results are reported as mean ± standard deviation (see also detailed dataset in Table
225 S1 in Supplementary material).
226 We found no significant difference in the consumption times (i.e. fragmenting and ingesting
227 the kernel) of the kernels of the three species examined (Figure 1a). Dormice spent
228 significantly different times in manipulating seeds of different trees (F2,43 = 118.51, p<0.001),
229 with longer times for C. avellana (76.0 ± 16.4 min) than acorns (Q. pubescens: 14.5 ± 2.6
230 min, Q. cerris: 16.5 ± 4.0 min); no significant difference was detected between Quercus
231 species (Holm's test p>0.05; Figure 1b).
232 Dormice ingested significantly different seed mass per time-unit (F2,43 = 57.65, p<0.001)
233 between hazelnut (0.034 ± 0.04 grams/min) and acorns (Q. pubescens: 0.133 ± 0.04
234 grams/min; Q. cerris: 0.117 ± 0.06). Differences were only significant between hazel nuts
235 and the two oaks (Holm’s test p<0.01) but not between oak species (Holm’s test p>0.05).
236 However, the amount of ingested calories per time unit (Q. pubescens: 0.22 ± 0.06; Q. cerris:
237 0.23 ± 0.04; C. avellana: 0.22 ± 0.03) was not significantly different between different
238 treatments (F2,43 = 0.36, p=0.70).
239
240 EXPERIMENT 2: Cafeteria tests
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241 We recorded a total of 42 trials (21 Q. cerris vs Q. pubescens; 21 Q. pubescens vs C.
242 avellana). Acorns of Q. pubescens were preferred by dormice when compared to Q. cerris
243 ones, with most individuals selecting the former as first choice (Binomial z=40.29, p<0.01)
244 and consuming more overall quantity (Binomial z=40.48, p<0.01). Dormice selected
245 hazelnuts during Q. pubescens vs C. avellana tests for the first choice (Binomial z=23.81,
246 p<0.01) but not for the total quantity consumed (Binomial z=7.14, p>0.05). We infer an order
247 of selection for the three species as follows: C. avellana > Q. pubescens > Q. cerris, with
248 hazel nuts and downy oak acorns being equally selected when considering the total amount of
249 seed consumed.
250
251 EXPERIMENT 3: Monospecific diet effects
252 Dormice treated with diets of different seed species showed different weight responses (F2,10
253 = 5.264, P<0.05), with significant differences between C. avellana and Q. cerris (Holm's test
254 p<0.01) and between Q. pubescens and Q. cerris (Holm's test p<0.05) but not between
255 hazelnut and downy oak (Holm's test p> 0.05). Dormice eating only Q. cerris acorns faced a
256 weight decrease whereas C. avellana seeds lead to an increase in weight (Figure 2a). A
257 monospecific diet of Q. pubescens acorns determined no weight fluctuations. The amount of
258 ingested seed mass (Figure 2b) also differed among treatments (F2,10 = 192.08, p<0.001), with
259 lower values for C. avellana compared to acorns of Q. pubescens (Holm's test p<0.001) and
260 Q. cerris (Holm's test p<0.001) oaks. Energy ingestion (Figure 2c) differed among treatments
261 (F2,10 = 32.350, p<0.001) with significant higher values for oaks (Holm's test p<0.001 for
262 both species).
263
264 Discussion
265 The hazel dormouse clearly acts a selection when different seeds are available. Acorn
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266 selection is made by this rodent upon specific seed characteristics, balancing the effects of
267 chemical compounds (e.g. tannins) and seed mechanical defence (i.e. pericarp hardness) on
268 the final energy intake. The use of naïve captive individuals suggests that the ability to
269 evaluate such seed characteristics is innate in this species (but see Muñoz and Bonal, 2008),
270 and is presumably mediated by the use of sensorial cues such as odour and taste.
271 Hazel dormice show a clear order of consumption when seeds with different characteristics
272 are offered. First choice is biased towards seeds with lower tannin content (Q. pubescens vs
273 Q. cerris) and/or more caloric seeds (C. avellana vs Q. pubescens) despite the higher degree
274 of mechanical protection of the former. Once found and opened, a more caloric seed like the
275 hazel nut ensures a high intake, minimizing costs of seed “search” and thus exposing the
276 rodent to lower predation risk. This is also confirmed by the smaller amounts of hazel nuts
277 ingested by dormice during monospecific diet experiments. Dormice selectively chose hazel
278 nuts as first choice, but subsequently consumed similar amounts of low-tannin acorns. This
279 non-significant difference between consumed mass of Q. pubescens and C. avellana may be
280 due to the low predation risk perceived in captivity, thus allowing dormice to relax food
281 selection and consume both species indifferently.
282 M. avellanarius need significant more time to open hazel nuts than acorns (more than one
283 hour for hazel nuts compared to about 15 minutes for acorns), thus confirming the predicted
284 effectiveness of mechanical defences by C. avellana, at least against small seed predators like
285 the hazel dormouse. Prolonged manipulation of hazel nuts leads to a lower mass ingestion per
286 time/unit by the dormouse, but the higher nutritional values of such highly defended seed
287 compensates this. Increased manipulation times due to harder and thicker pericarps constitute
288 a complementary defensive strategy that makes seeds less attractive to predators (Yang et al.,
289 2012; Zhang and Zhang, 2008). Moreover, a rodent is, presumably, visually and acoustically
290 more evident to potential predators when engaged in opening a seed. In addition, seed
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291 defences are subject to a trade-off between biochemical and mechanical mechanisms (Chen et
292 al., 2012) so that seed predators may specialize to overcome one mechanism or the other.
293 Monospecific diet experiments indicate that dormice eating seeds of different tree species do
294 show differences in their capability of gaining weight, with preferred species allowing an
295 actual benefit in terms of fat storage. Seeds with high levels of tannins led to weight decrease,
296 despite the large amounts of seed mass ingested by dormice, comparable to the tannin-free
297 Quercus acorns. This result is in line with Shimada and Saitoh (2003), who found that
298 Japanese wood mice (A. speciosus) showed a marked decrease in their body weight when
299 subjected to monospecific diets of the high tannin-content acorns of Q. mongolica. Even
300 species in the same genus may show different degrees of tolerance to tannins (e.g. Sciurus
301 spp.: Kenward and Holm, 1993), a trait potentially affecting interspecific competitive
302 dynamics.
303 Tannins are known to alter palatability (Spalinger et al., 2010) and digestibility (Hagerman et
304 al., 1992) of seeds and other plant parts, and thus can influence food choice of
305 herbivore/granivore animals like rodents (Wang et al., 2013; Xiao et al., 2008). However,
306 many herbivore mammals evolved a class of tannin-binding proteins, that is a family of
307 proteins which reduces the detrimental effects of tannins on digestion (Hagerman and
308 Robbins, 1993; Shimada, 2006). Acclimation, i.e. an increase in the production of tannin-
309 binding proteins, by means of gradual exposition to tannins is known to occur in some acorn-
310 eating rodents (Shimada et al., 2004; Takahashi and Shimada, 2008), but no study reports
311 such proteins for glirids (Shimada, 2006). The higher values of seed mass consumed by
312 dormice when eating acorns compared to hazel nuts may also be another response to the
313 impoverished nutrient acquisition due to tannins. Rodent species which lack tannin-binding
314 proteins may compensate the diminished energy intake by increasing the amount of seed
315 mass ingested, albeit being potentially exposed to the detrimental effects of high tannin
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316 intake. This strategy though does not seem to efficiently compensate the effects of tannins, as
317 dormice eating only acorns of the highly tannin-content Q. cerris, generally decreased in
318 weight.
319 Both acorns and hazel nuts play a consistent role in the diet of the hazel dormouse in its
320 whole range (Bright and Morris, 1996; Juškaitis and Baltrūnaitė, 2013) as well as of other
321 forest-dwelling rodents (Kollmann and Schill, 1996); tree species composition of woods
322 along the hazel dormouse distribution may thus result in different levels of suitability, e.g.
323 woods dominated by tannin-rich acorns could be less suitable, because of a lower weight gain
324 efficiency during the critical time before hibernation.
325 Our study indicates that M. avellanarius forages selecting seeds by balancing net energy
326 intake with seed manipulation times, suggesting that dormouse is a seed predator specialized
327 on seeds with thick and/or hard pericarps. We acknowledge that further studies, both in
328 captivity and in nature, with larger sample size and dealing with a larger number of tree
329 species are needed to generalize our findings on hazel dormouse foraging ecology. In
330 addition, we also acknowledge that we conducted our experiments with cultivated hazel nuts,
331 which may slightly differ from seeds of wild C. avellana in their biochemical composition.
332 Studies on other species in the wild also report strong selection by seed predators, with seeds
333 characterized by low net energy intake (due to low caloric content, large dimensions and/or
334 high chemical defence) being generally avoided by seed-caching rodents (Molinari et al.,
335 2006; Yang et al., 2012). Furthermore we stress that seed choice in natural habitats is highly
336 affected by extrinsic factors such as the presence of conspecifics and predators (Sunyer et al.,
337 2013), competitor species (Kenward and Holm, 1993; Muñoz et al., 2009; Wauters et al.,
338 2001) and even seed parasites (Muñoz and Bonal, 2008; Perea et al., 2012).
339 Forest-dwelling rodents have a relevant effect on dispersal and survival of tree species
340 (Hulme, 1998; Vander Wall, 2010; Velho et al., 2012; Yang and Yi, 2012), so that
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341 understanding the mechanisms underlying seed selection by seed predators at a fine scale
342 (Wang et al., 2013) is fundamental. The study of the interactions between plants and rodents
343 in forests may also lead to guidelines for the conservation and management of both forests
344 and forest-dwelling rodents.
345
346 Acknowledgements
347 We thank Elisa Russo and Andrea Schiavano for helping us in carrying out part of the
348 experiments, and the Ethoikos foundation for kindly providing data on biochemical
349 composition of acorns.
350
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507 Figure legends
508 Figure 1. Seed consumption. Seed consumption (a) and seed manipulation (b) times (Mean
509 ±SD, in minutes) for single seeds of three different tree species by captive hazel dormice
510 Muscardinus avellanarius. CA = Hazel - Corylus avellana; QP = Downy oak - Quercus
511 pubescens; QC = Turkish oak - Quercus cerris. Significant differences among species are
512 indicated on bars: * = p<0.01; n.s. = p>0.05.
513
514 Figure 2. Effects of seeds on body condition. Weight gain/loss (g) (A), ingested mass of
515 acorn (g) (B) and ingested energy intake (Kcal) (C) by captive dormice after each
516 monospecific diet. CA = hazel - Corylus avellana; QP = downy oak - Quercus pubescens; QC
517 = Turkish oak - Quercus cerris.
518
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519
520 Tables
521 Table 1. Biochemical composition of seeds from three different tree species. Data on acorns
522 was kindly provided by the Ethoikos foundation (Fondazione Ethoikos, Gasperini et al. in
523 prep).
Species Kcal / Tannins mg / Kg Lipids % Carbohydrates % Proteins % Ashes %
100 g
Quercus pubescens 154 6440± 0.50 27.40 2.62 13.90
640
Quercus cerris 152 13200± 0.75 23.10 2.37 21.50
1300
Corylus avellana * 437 7500± 3.50 40.40 48.20 7.90
1300
524 *data from Xu and Hanna, 2011.
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