DOI: 10.5061/dryad.x0k6djhxm
title: Effects of seed mass on seed foraging behaviors of two sympatric rodent species

description: Throughout a semi-natural experiment, we investigated seed use by two
 sympatric rodent species of different sizes, Apodemus flavicollis and A.
 sylvaticus, focusing on how Quercus cerris acorn mass affected seed
 predation, removal and dispersal by mice. A total of 20 adult A.
 flavicollis and 25 adult A. sylvaticus were individually tested in an
 open-air experimental enclosures. 40 Q. cerris acorns were collected in
 the same forest where the rodents had been cought and were then weighed
 with a digital balance (to the nearest 0.01 g) and individually marked
 with a univocal alphanumeric code written on the seed shell surface. Each
 test started when we placed the 40-acorn sample on the ground at
 the center of the enclosure and lasted for three consecutive days. At the
 end of the test, the final seed fate of each acorn or acorn leftover were
 recorded and classified as: (1) eaten (partially or
 completely) in situ (i.e., center of the enclosure), (2) not
 eaten in situ, (3) removed and eaten (partially or completely), (4)
 removed and not eaten (i.e., seeds that potentially could have been
 successfully dispersed). Animals were released at their capture site at
 the end of the tests, after three days of captivity. We used generalized
 linear mixed models (GLMMs) with binomial distribution (family = binomial,
 link = logit) to investigate the relationship between acorn fate
 and acorn mass and to estimate the probability of a rodent specific
 response pattern (i.e., foraging strategy) to seeds. The individual seed
 was considered as a sampling unit and seed fate was modelled as a binomial
 variable. We structured four models for foraging strategy and final acorn
 fate: a predation model (binary data: 0 = not eaten, 1 = eaten), a removal
 model (0 = not removed, 1 = removed), a site-specific predation model (0 =
 eaten and not removed, 1 = eaten and removed), a dispersion model (0 =
 removed and eaten, 1 = removed and not eaten). In the GLMMs, the
 individual rodent was included as a random factor, rodent species as
 categorical factor and acorn mass as covariate with an interaction term.
 To evaluate interspecific differences in foraging strategies, we estimated
 marginal trends from the GLMMs, enabling direct comparison of acorn mass
 effects on seed fate between species while maintaining model integrity. To
 account for potential nonlinear effects of seed mass on removal observed
 in the raw data we included a quadratic term for acorn mass to test for
 unimodal patterns in seed removal. Given the difference in body mass
 between individuals of the two rodent species we tested, rodent body mass
 was also included as a covariate in the removal model to account for
 individual variation in handling ability. Finally, to assess interspecific
 differences in the mass of removed acorns, we used linear mixed models
 (LMMs), with the individual rodent included as a random factor and rodent
 species as categorical factor. We applied the same model structure to test
 for differences in the acorn mass to rodent body mass ratio associated
 with removed acorns. We detected a species-specific response in
 seed predation: A. flavicollis was more likely to predate heavier acorns,
 while seed mass had no significant effect on the probability of seed
 consumption for A. sylvaticus. Removal probability did not differ between
 species suggesting similar removal patterns with respect to seed mass
 across species, which were more likely to remove intermediate-sized seeds.
 Apodemus flavicollis removed acorns with a seed mass to rodent mass ratio
 significantly lower than the one observed for A.
 sylvaticus. After removal, the likelihood of predation versus
 that of dispersal resulted to be species-specific. Specifically, it did
 not vary with seed mass for A. flavicollis, while A. sylvaticus tended to
 disperse heavier acorns. These findings suggest that the two species might
 play distinct roles in determining seed fate. 
description: # Effects of seed mass on seed foraging behaviors of two sympatric rodent
 species of different sizes ## Description of data Semi-natural experiments
 revealed that seed use, and the consequent seed fate, can be strongly
 influenced by seed mass in Apodemus flavicollis and A. sylvaticus, two
 wood mouse species that often coexist in European forests. In addition,
 seed mass-related foraging behaviors differences emerged between the two
 species during the experiments. These findings highlight the importance of
 considering species-specific foraging behaviors when evaluating the
 ecological role of co-occurring hoarding rodents in seed dispersal.
 Originators: Stefania Gasperini Date of data collection: 2018-2019
 Geographic location(s) of data collection: La Selva Forest (43°13ʹN,
 11°4ʹE, Central Italy) ## Data files and variables
 **Gasperini_et_al._2025_DB_PREDATION_MODEL.csv** Dataset for the predation
 model reporting data on whether an acorn is eaten or not. * ID_ANIMAL:
 identification number of the animal tested * SPECIES: species of the
 tested animal. AF: *Apodemus flavicollis*; AS: *A. sylvaticus* * ID_ACORN:
 identification code of tested acorns * WEIGHT_ACORN: weight of tested
 acorns in grams * CONSUMPTION: dicotomic data. 0: eaten; 1: not eaten
 **Gasperini_et_al._2025_DB_REMOVAL_MODEL.csv** Dataset for the removal
 model reporting data on whether an acorn is removed or not from the centre
 of the arena. * ID_ANIMAL: identification number of the animal tested *
 SPECIES: species of the tested animal. AF: *Apodemus flavicollis*; AS: *A.
 sylvaticus* * ID_ACORN: identification code of tested acorns *
 WEIGHT_ACORN: weight of tested acorns in grams * RATIO_A_M: acorn mass
 (i.e., acorn weight, g) to rodent body mass (i.e., rodent weight, g) ratio
 associated with removed acorns. Each rodent was weighted before the test
 started * REMOVAL: dicotomic data. 0: removed from the centre of the
 arena; 1: not removed from the centre of the arena * POSITION:
 identification code of the final position of each acorn. R: removed from
 the centre of the arena; NR: not removed from the centre of the arena
 **Gasperini_et_al._2025_DB_SITE_SPECIFIC_PREDATION_MODEL.csv** Dataset for
 the site-specific predation model reporting data on eaten acorns, only
 specifying the site of consumption. * ID_ANIMAL: identification number of
 the animal tested * SPECIES: species of the tested animal. AF: *Apodemus
 flavicollis*; AS: *A. sylvaticus* * ID_ACORN: identification code of
 tested acorns * WEIGHT_ACORN: weight of tested acorns in grams *
 SITE_SPECIFIC_CONSUMPTION: dicotomic data. 0: eaten and not removed from
 the centre of the arena; 1: eaten and removed from the centre of the arena
 **Gasperini_et_al._2025_DB_DISPERSION_MODEL.csv** Dataset for the
 dispersion model reporting data on removed acorns, only specifying whether
 they were eaten or not. * ID_ANIMAL: identification number of the animal
 tested * SPECIES: species of the tested animal. AF: *Apodemus
 flavicollis*; AS: *A. sylvaticus* * ID_ACORN: identification code of
 tested acorns * WEIGHT_ACORN: weight of tested acorns in grams *
 DISPERSION: dicotomic data. 0: removed from the centre of the arena and
 eaten; 1: removed from the centre of the arena and not eaten