Prey size as a critical factor for bird bone taphonomy in Eagle Owl (Bubo bubo) pellets

Abstract

Each predator hunts and consumes its prey in a particular way. Consequently, the traces left by predators on bones might vary according to the manner in which the prey are processed. For this reason, prey size has been proposed as a key issue that affects the damage inflicted on bones. The Eagle Owl (Bubo bubo) is one of the main potential predators of small prey found in archaeological sites. However, detailed taphonomic research describing bone accumulations produced by this nocturnal raptor is still scarce. The aim of the present work is to describe a modern accumulation of pellets originated by the Eagle Owl from this perspective, with a specific focus on birds. Particular attention is paid to prey size to evaluate the real significance of this variable when assessing bone damage. The results confirm that bone alterations reflect how prey was ingested, as the bones show greater damage with increasing prey size. This finding emphasises the complexity of characterising archaeological accumulations, as the alterations will vary according to prey size. In addition, bone architecture—or other aspects that cannot be controlled—may hinder accurate diagnosis and should be taken into account.

Contribution of small mammal taphonomy to the last Neanderthal occupations at the El Salt site (Alcoi, southeastern Spain)

“…In summary, the results obtained in this work suggest a large owl species—more specifically, the European eagle owl—as the most likely predator responsible for the small mammal fossil accumulation in Units X and V. We have found no ground to consider any mixture with any other predator as described in other cases (e.g., Fernández-Jalvo, 1995; Fernández-García et al, 2020). Apart from the taphonomic traits, Bubo bubo is considered one of the main rabbit predators in the Iberian Peninsula and in Mediterranean ecosystems (Hiraldo et al, 1975; Donázar, 1988, 1989; Serrano, 1998; Rufà and Laroulandie, 2019), which agrees with our results. Its current hunting area ranges between 4–20 km 2 , depending on the quality of territory and availability of prey (Cramp, 1985; León-Ortega, 2016).…”

Who Killed the Small Mammals of Ittenheim (Northeastern France)? An Integrative Approach and New Taphonomic Data for Investigating Bone Assemblages Accumulated by Small Carnivores

“…As recently demonstrated (e.g., [37][38][39]), prey size does matter, and is a key factor for interpreting the traces left on bones by predators. Accordingly, bone remains were assigned to four size categories: (1) leporids and fox; (2) hamster, rat, muskrat, and hedgehog; (3) larger voles (Arvicola amphibius and A. sapidus); and (4) smaller voles and mice, including Microtus sp., Clethrionomys glareolus, and Apodemus sp.…”

“…For instance, among the eight listed by Denys and Cochard [24] for red foxes (Vulpes vulpes), only one concerns rodents [31], with the rest focusing on larger prey species, such as lagomorpha and/or birds [32][33][34][35][36]. This is important as prey size has a major influence on the traces left on bone remains [3,33,[37][38][39]. Studies focusing on the taphonomy of small mammal remains are also rare [40][41][42][43][44][45], especially for European species [18,31,38,46], and often mix rodent species of different sizes [44]).…”

Unravelling the Taphonomic Stories of Bird Bones from the Middle Pleistocene Layer VIII of Grotte Vaufrey, France

“…As a consequence of this process, an important number of remains present digestive corrosion in light or moderate degrees. They could also have mechanical modifications in percentages from 0.1% to 7.7%, depending on the prey [20][21][22][39][40][41][42]. In the case of diurnal birds of prey, if the prey is ingested, digestive damage is intense or extreme to most of the bones.…”

“…This formula was applied by dividing the MNE found for each bone category by the total number of elements expected to be found, based on the MNI represented, and is expressed as a percentage. After the initial identification, the remains were classified, taking into account six larger categories according to the bird's weight [40]: size 1 (<50 g); size 2 (51-150 g); size 3 (151-250 g); size 4 (251-500 g); size 5 (501-1500 g); and size 6 (>1501 g). This allowed for the calculation of different indexes with more precision.…”