AN INVESTIGATION OF PATTERNS OF MAMMALIAN SCAVENGING IN RELATION TO VERTEBRATE SKELETAL REMAINS IN A NORTHWEST EUROPEAN CONTEXT: FORENSIC APPLICATIONS Alexandria Young A thesis submitted in partial fulfilment of the requirements of Bournemouth University for the degree of Doctor of Philosophy November 2013 Bournemouth University 1 This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and due acknowledgement must always be made of the use of any material contained in, or derived from, this thesis. 2 An investigation of patterns of mammalian scavenging in relation to vertebrate skeletal remains in a Northwest European context: forensic applications Alexandria Young ABSTRACT Mammalian scavenging, disarticulating, scattering and removal of human remains can alter and obscure both soft tissue and skeletal remains which are essential to making interpretations and identifications during forensic investigations. The effects of scavenging vary between regions, environments, scavenger species, and crime scene scenarios due to a variety of factors. Nonetheless, there is a gap in the knowledge of scavenger species found within Northwestern Europe. The red fox (Vulpes vulpes) and Eurasian badger (Meles meles) are the largest wild mammalian scavenger species inhabiting peri-urban and rural environments within Northwestern Europe. These mammalian scavengers have dentitions and bite forces capable of heavily modifying and widely transporting human remains yet there are currently no species-typical and region-specific studies of these scavengers and their impacts on forensic investigations and physical searches for human remains. Forensic scientists, investigators and police search officers have been forced to rely on anecdotal evidence and scavenging studies focused on scavengers not found in this region. Scavenging studies have previously concentrated on scavenger species found in North America and Africa, such as coyote (Canis latrans), wolf (Canis lupus), hyena (Crocuta crocuta), lion (Panthera leo) and leopard (Panthera pardus), which have differing species-typical scavenging behaviour and patterns in comparison to foxes and badgers. Likewise, knowledge of the characteristics of the effects on bone surfaces of fox and badger scavenging is lacking, more so for the latter scavenger. The overall aim of this thesis is to aid forensic investigations by filling the gaps in the knowledge and identification of red fox and Eurasian badger species-typical scavenging behaviour and patterns. Avian scavenging can also modify soft tissue and skeletal remains. The buzzard (Buteo buteo) and carrion crow (Corvus corone) are the most common avian scavengers within this region. The scavenging behaviours of these avians modified soft tissue and affected mammalian scavengers’ scavenging behavours. 3 A survey of police search officers within the U. K. indicated that the scavenging of surface deposited human remains within this region is common and that scavenging affects the recovery rates of remains. Despite the impact of scavenging on the recovery of scavenged remains, there is a lack of knowledge and literature available to forensic scientists, investigators, and police search officers to aid in the identification of scavenger species and scavenger species-typical scavenging behaviour and patterns. Thus these forensic professionals have been relying primarily on anecdotal evidence to identify scavengers or have not made efforts to identify scavengers. Experiments, conducted in southern England, using deposited deer (Cervus nippon; Capreolus capreolus) and the observation of captive scavengers found that within a woodland environment common scavengers include wood mouse (Apodemus sylvaticus), grey squirrel (Sciurus carolinensis), carrion crow, buzzard, Eurasian badger, and red fox. Scavenging activities by all scavenger species observed at remains were affected in various ways by seasonality, trophic resources, territoriality, insect activity, carcass size and condition, and decomposition. Of those scavengers, the red fox was the most frequent scavenger of surface deposited remains. The species-typical scavenging behaviour and pattern, as well as bite mark dimensions, of the red fox proved to differ to that of badgers and other canids, such as domestic dogs (Canis familiaris), coyotes and wolves. The benefits of the knowledge of scavenger species-typical scavenging behaviour and pattern to forensic investigations and physical searches were assessed by applying the results gained from the experiments within this research to current forensic investigations and search exercises performed with police search officers. The application of information on species-typical scavenging behaviour and patterns was found to improve police search officers’ search and recovery efforts of scavenged remains. 4 CONTENTS 1. GENERAL INTRODUCTION…………………………………………………26 1.1 TAPHONOMY………………………………………………………..27 1.1.1 Taphonomy in archaeology…………...…………..……..27 1.1.2 Taphonomy in forensic anthropology and forensic archaeology………………………………………………………..28 1.2 SCAVENGERS: EFFECTS ON HUMAN REMAINS………….....43 1.2.1 Soft tissue damage…………………….…………............43 1.2.2 Modification of skeletal remains………………………….44 1.3 RODENT AND AVIAN SCAVENGING…………….………….......53 1.3.1 Rodent scavenging…………………………….....……....53 1.3.2 Avian scavenging…………………..……………..……....54 1.4 RED FOX (VULPES VULPES) AND EURASIAN BADGER (MELES MELES): BEHAVIOURAL ECOLOGY AND SCAVENGING BEHAVIOUR…………………………………………………………...….55 1.4.1 Red fox and Eurasian badger: introduction ......….…....56 1.4.2 Red fox and Eurasian badger diet……………..……......60 1.4.2.1 Red fox foraging behaviour…………………….61 1.4.2.2 Eurasian badger foraging behaviour………....62 1.4.3 Recovery Distances of Scavenged Remains…………..62 1.4.3.1 Red fox home range: recovery of scavenged and scattered remains ......…………..……………………..…63 1.4.3.2 Eurasian badger home range: recovery of scavenged and scattered remains………………………64 1.5 THESIS AIMS AND OBJECTIVES………………….……………..65 1.6 THESIS STRUCTURE………………………………........………..66 2. SCAVENGING IN NORTHWESTERN EUROPE: A SURVEY OF U.K. POLICE SEARCH OFFICERS……………………………………………..…...69 2.1 INTRODUCTION……………………………………………………69 5 2.2 MATERIALS AND METHODS……………………………………..70 2.3 RESULTS…………………………………………………………….75 2.4 DISCUSSION………………………………………………………...78 2.5 CONCLUSION……………………………………………………….81 3. AN EXPERIMENTAL STUDY OF VERTEBRATE SCAVENGING BEHAVIOUR IN A NORTHWEST EUROPEAN WOODLAND CONTEXT: RODENT AND AVIAN SCAVENGERS……..…………………………………82 3.1 ABSTRACT…………………………………………………………..82 3.2 INTRODUCTION…………………………………………………….82 3.3 MATERIALS AND METHODS……………………………………..85 3.4 RESULTS………………………………………………………….…90 3.4.1 Baits…………………………………………………………90 3.4.2 Deer case studies…...…………………………………….92 3.4.2.1 Deer 1…………………………………………….97 3.4.2.2 Deer 2…………………………………………...100 3.4.2.3 Deer 3…………………………………………...100 3.4.2.4 Deer 4…………………………………………...100 3.4.2.5 Deer 5…………………………………………...101 3.4.3 Ungulates as taphonomic agents………………………104 3.5 DISCUSSION……………………………………………………….104 3.5.1 Rodent scavenging……...………………………………105 3.5.2 Avian scavenging………………………...……………..107 3.5.3 Ungulates as taphonomic agents………………………109 3.6 CONCLUSION……………………………………………………...110 4. AN INVESTIGATION OF RED FOX (VULPES VULPES) AND EURASIAN BADGER (MELES MELES) SCAVENGING, SCATTERING AND REMOVAL OF DEER REMAINS: FORENSIC IMPLICATIONS AND APPLICATIONS…………………………………………………………………111 4.1 ABSTRACT…………………………………………………………111 6 4.2 INTRODUCTION…………………………………………………...111 4.3 MATERIALS AND METHODS……………………………………113 4.3.1 Behaviour of captive foxes and badgers.……………...114 4.3.2 Behaviour of wild foxes and badgers….……………….115 4.3.3 Statistical methods……………………………………….121 4.4 RESULTS…………………………………………………………...121 4.4.1 Behaviour of captive foxes and badgers ……………..121 4.4.2 Behaviour of wild foxes and badgers ..………………..128 4.4.3 Scene investigation, search, and recovery: scattering and dispersal of scavenged surface remains………………...145 4.4.3.1 Deer 1…………………………………………...151 4.4.3.2 Deer 2………………………………………..….153 4.4.3.3 Deer 3…………………………………………...155 4.4.3.4 Deer 4………………………………………..….157 4.4.3.5 Deer 5…………………………………………...159 4.5 DISCUSSION……………………………………………………….163 4.5.1 Badgers versus foxes………………………………..….164 4.5.2 Scavenging behaviour and pattern of the red fox…………………………………………………………....…...165 4.5.3 Comparison of deer and human remains: red fox scavenging behaviour and pattern.……………………...........169 4.5.4 Comparison of deer and human remains: red fox scattering pattern………………………………………………..172 4.6 CONCLUSION……………………………………………………...176 5. SCAVENGER SPECIES-TYPICAL ALTERATION TO BONE: USING BITE MARK DIMENSIONS TO IDENTIFY SCAVENGERS ………….…………………………………………………………………………178 5.1 ABSTRACT…………………………………………………………178 5.2 INTRODUCTION…………………………………………………...178 5.3 MATERIALS AND METHODS……………………………………183 5.4 RESULTS…………………………………………………………...188 7 5.4.1 Deer ………………………………………………………188 5.4.2 Bones scavenged by captive red fox……………….….200 5.4.3 Bones scavenged by captive Eurasian badger.….......203 5.4.4 Bones scavenged by small-sized domestic dogs….....206 5.4.5 Bones scavenged by large-sized domestic dogs: Staffordshire bull terriers………………………………………..208 5.4.6 Cow (Bovidae) bones..…………………………………..212 5.4.7 Comparison of samples of scavenged bones………...213 5.4.7.1 Pit dimensions………………………………….213 5.4.7.2 Score dimensions……………………………...213 5.4.7.3 Puncture dimensions………………………….214 5.5 DISCUSSION……………………………………………………….214 5.5.1 Hypothesis 1……………………………………...215 5.5.2 Hypothesis