Methodology

2. METHODOLOGY

2.1. Data collection

Barnebys (a popular auctioneer and antique dealer search engine), eBay UK (a general online marketplace) and Antiques Atlas (a specialist online marketplace) were chosen as study websites as recent reports have shown that these websites frequently advertise ivory items (eg, Lau et al, 2016; Alfino and Roberts, 2020; Venturini and Roberts, 2020; Parry, 2021).

Searches were conducted using the words ‘ivory’, ‘tusk’, ‘teeth’, ‘scrimshaw’ (an engraved item), ‘okimono’ (a decorative sculpture), ‘netsuke’, ‘faux ivory’, ‘ivorine’ and ‘bone’. The same nine keywords were searched every day on each website. These nine keywords were chosen on the basis that previous studies have shown they produce results for ivory (Harrison, Roberts and Hernandez-Castro, 2016; Baker et al, 2020; Venturini and Roberts, 2020) and a preliminary search of each website prior to the start of the investigation produced results relating to all relevant ivory-bearing species.

For Barnebys, the results were refined to the country of ‘United Kingdom of Great Britain and Northern Ireland’. For the purpose of this analysis, the Channel Islands were included in the database as an auction house in Guernsey appeared under this search result. For eBay, the search results were refined to the categories ‘Antiques’ and ‘Collectables’ with the item location set to ‘UK only’. This meant there were two separate searches each day on eBay for each of the nine keywords (totalling 18 unique daily searches). For Antiques Atlas, instead of searching ‘ivory’, the ‘Ivory Antiques’ search was selected and then ordered by ‘date added’.

All keywords were searched every morning at 9:00am (±30 minutes) from 8 November to 8 December 2021 inclusive, and item details for every relevant listing not already on the database was recorded. For each listing, the following information was recorded: date searched, website, keyword searched, product title, seller, seller location, product type, whether the majority of the item was made from ivory, material description, whether the ivory description was overt or covert, ivory-bearing species and the current/estimated price. When an estimated price range was given, the lower figure of the range was recorded. Only eBay provided a date for when each item was uploaded, so this was also recorded for eBay items. The search date was used to estimate the average number of listings per day for Barnebys and Antiques Atlas, and the upload dates were used to calculate the average number of new eBay listings per day.

The products were split into the same four commodity types used by Lau et al (2016), which were jewellery, figures, household goods and personal items. If there was more than one item in the listing, the most numerous category was assigned. If there was the same number present for two or more categories, then the category was assigned based on the estimated cumulative ivory volume of the items. For the purpose of these groupings, all ornamental items were counted as ‘figures’, except for miniature paintings which were allocated as personal items, as per Lau et al’s (2016) study.

If no material related to the ivory element of the product was selected in the item specifics, then the material described in the title or description was recorded. An item was counted as an ‘overt listing’ if the seller described the item as ivory (eg, either directly or indirectly, such as ‘hippo tusk’) and this was confirmed by the images. If a listing failed to provide a description of the material or if it described the ivory as a different material, such as bone, it was counted as a ‘covert listing’. If an item was made from more than one material, but the seller only described the non-ivory material, this was also counted as a covertly described item.

2.2. Visual identification of material

Any listing which may have included ivory from the image(s) and description was investigated, but only items which could be reasonably determined as ivory were recorded. This included items with small amounts of ivory, such as inlaid furniture and teapots with ivory insulators. Listings which included the keyword but where the item was clearly not made from ivory (eg, ivory-coloured carpets) were discounted. The benefit of the doubt was always given to sellers, ie, items were not recorded unless they met the criteria described in the categories below. Duplicate listings were identified and removed.

The categories used by Venturini and Roberts (2020) have been adapted for this investigation. Identified covert ivory listings were assigned to one of four categories which indicated the degree of uncertainty in identifying the material from the images:

Category 1 (C1): Obvious ivory – Animal-identifying features clearly visible in multiple sections, or seller admits it is ivory on their own website or elsewhere in the description.

Category 2 (C2): Highly likely ivory – Animal-identifying features clearly visible in single section and the morphology indicates the ivory originates from this animal.

Category 3 (C3): Likely ivory – Animal-identifying features are not clearly visible, only faintly discernible. Elements such as the colour, texture, price, description and style also suggest it is ivory.

Category 4 (C4): Suspected ivory – Image angles and quality means animal-identifying features not visible, but the colour, texture, price, description, style and brand history (if applicable) suggest it is ivory.

2.3. Visual identification of species of origin

In addition to elephants, identification of the likely source of ivory items was limited to species in the scope of DEFRA’s call for evidence (DEFRA, 2019), namely common hippopotamus, orca, narwhal, sperm whale, walrus, common warthog, desert warthog and mammoth. Listings which included teeth from other mammals were noted but not included in this analysis.

The 4th edition of the Identification Guide for Ivory and Ivory Substitutes (Baker et al, 2020) was the main source used to identify ivory-bearing species. Images present in listings were visually inspected to determine what species the ivory was likely to have been derived from. Items with Schreger lines were presumed to be elephant, unless it could be clearly identified from the angles or evidence of fossilisation that it was likely to be mammoth. The species was allocated as unknown if the listing did not indicate the ivory-bearing species and the species could not be identified with confidence from the image(s).

2.4. Statistical analysis

Initial descriptive statistics were conducted to determine the number of ivory items which belong to each value within the variables. A two-sample t-test assuming equal variances was conducted to identify any significant difference in the value of elephant and non-elephant ivory. A one-way ANOVA analysis was used to determine whether the product type determined the value of the ivory. All statistical analyses were carried out using Microsoft Excel.