Practical recommendations for archaeologists on handling animal remains

1.  Why these recommendations?

At this stage, the association provides recommendations for managing animal remains uncovered in archaeological contexts. These guidelines are directed at archaeologists, as well as geologists and soil scientists working with excavation companies, university institutes, heritage organizations, or museums. The recommendations serve as practical guidance for the planning phase, excavation, storage, and scientific analysis (for further information, refer to the guidelines by Historic England and the Association for Environmental Archaeology). In some instances, existing guidelines from other authorities may apply and take precedence over these recommendations.

2. Handling Animal Bones During Excavation and Recovery
Questions concerning economic activity, historical landscapes, and the acquisition of raw materials in prehistoric and protohistoric sites are of considerable interest to archaeological research. Typically, meaningful insights rely on archaeobiological analyses, making botanical and zoological remains, as well as pottery and other artifacts, equally critical as archaeological evidence.

2.1. Project design
Archaeobiological finds are present in nearly every material complex and field research project, offering valuable supplementary information. Therefore, the costs associated with archaeozoology should always be factored into project planning. Even if an archaeozoological analysis is not scheduled during the project or immediately afterward, proper initial handling, management, and packaging of finds must be accounted for in the budget. Additionally, incorporating archaeobiology demonstrates a higher level of expertise, whether for private excavation companies serving clients or for research excavation proposals.

2.2. Archaezoology on the excavation site
2.2.1. Introduction
To achieve the best results, an archaeozoologist should be involved from the outset of project planning. During the excavation, having an archaeozoologist on-site is recommended, depending on the nature of the finds. Complete and partial skeletons should ideally be documented and recovered by specialists. If this is not feasible, accurate documentation using photographs and drawings is essential, followed by block recovery when necessary.
Complete skeletal parts that clearly belong together should be treated as distinct find units to ensure clear classification later. Examples include jaws with associated teeth, cranial fragments with horns, and all bones of young animals, where the joints are often unfused and prone to detachment from long bones.
As with all other artifacts, animal bones must be meticulously categorized within the documentation. Specimens lacking a clear stratigraphic context or association lose much of their scientific value.
It is recommended to analyze all animal remains from an excavation. If this is not feasible for a particular project, the selection of features for analysis should be determined in consultation with the archaeozoologist. Special consideration should also be given to the potential for collecting sediment samples, which can preserve small zoological remains. These samples may enable detailed analysis later, for instance, to address microclimatological questions.

2.2.2. Expected results
Regardless of the research question, the identification and scientific analysis of animal bones can include the following aspects:

• Species list
• Skeletal parts lists / skeletal elements
• Age class and sex distribution
• "Wuchsform" calculation
• Pathologies
• Slaughter marks
• Burn marks
• Processing marks and artefacts
• seasonal determination
• Drawing and/or photographic documentation of special features
• diachronic and synchronous evaluation
• landscape reconstruction
• further scientific investigations, such as isotope and genetic analyses

2.2.2.1. Sieving vs. sludging
Hand-picking skeletal material is the most common method used in archaeological excavations, effectively capturing remains of larger domestic animals. However, this approach often results in the loss or underrepresentation of bones from young animals and smaller species, such as birds, fish, amphibians, reptiles, and mollusks.
Sieving is conducted during excavations to recover small bones and other animal remains. Typically, mesh sizes of 2 mm are used, with the choice of dry or wet sieving depending on soil conditions and available equipment. For finer recovery, "mudding" employs mesh sizes of 0.5–1 mm. Larger bones are manually sorted from the samples, while smaller fragments are identified using a magnifying glass or microscope. This technique is also effective for recovering burnt and calcined bones.

Although sieving and sludging require more time and incur higher costs for subsequent identification, these methods are invaluable for detecting small animal species. For instance, while nets, fishhooks, fish traps, and other evidence of extensive fishing were frequently uncovered along the Oder River and in numerous Germanic settlements near water during the Roman Imperial period, fish bones were rarely found or entirely absent.
Excellent examples of comprehensive excavation and recovery methods employing sieving and sludging include the Wurt Feddersen Wierde site, where a highly diverse fauna was documented, and even evidence of parasites was identified. Similarly, at the oppidum of Manching in Bavaria, the sludge flotation process was used to recover fish scales, providing clear evidence of the importation of delicate Mediterranean fish during Roman times.
From an archaeobiological perspective, sieving or sludging features is highly recommended. For research excavations, these methods should ideally be incorporated during the preliminary planning stage for selected large features expected to yield chronologically significant finds. This approach should also be applied to rescue excavations involving extensive find contexts.
While direct sunlight is often unavoidable during excavations, it can cause significant damage to freshly exposed skeletal remains. In summer conditions, efforts should be made to shade the remains and prevent them from drying out too quickly by promptly covering them with tarpaulins.

2.2.2.2. Recovery practice
The initial treatment of animal bone finds must meet criteria similar to those applied to prehistoric pottery. Wet bones are highly fragile and prone to disintegration, which can complicate subsequent processing, artificially inflate the count of bone finds (KNZ/NISP/n), and skew evaluation results. Therefore, careful handling during recovery is essential.
For larger fragments that clearly belong together, adhesives can be used to secure them before recovery, but only after consulting the restoration departments of the relevant federal monument protection authorities. Polyvinyl acetate and cyanoacrylate are recommended for fully reversible bonding (solvent: acetone), as they react quickly even in the presence of residual moisture and are considered chemically stable based on current knowledge. Acrylic esters and amine resins are also effective curing agents. Traditionally, wood glue has been used as well.
If adhesives are applied during excavation, the precise chemical name of the agents used must always be recorded in the documentation. However, it is important to note that all curing methods have potential drawbacks, such as obscuring morphologically significant features or traces of human activity on the bones.
To prevent mold growth, finds should not be packed in airtight containers immediately after recovery. Stackable Euronorm boxes made of polyethylene (PE) or high-density polyethylene (HDPE) with perforated walls, perforated plastic bags, or durable paper bags are recommended to ensure proper ventilation. Once the finds have been carefully cleaned and completely dried, they can be repacked more compactly, similar to the process for ceramics.
It is crucial to use packaging materials that are as chemically neutral as possible, such as plastic bags free from plasticizers that could evaporate. Based on current knowledge, all PE plastics are considered the most suitable option.

2.2.2.3. Soil samples
If sludging or sieving of features cannot be performed due to time limitations, soil samples may be collected. The number, quantity, and packaging of these samples must be coordinated with the relevant monument protection authorities in each federal state. Since storage with residual moisture is only feasible under constant, low-temperature conditions, all soil samples should be fully dried before final packaging to prevent mold growth (see section 3.1.1).