Mining morphometrics and age from past survey photographs.

BACKGROUND: Researchers often document wildlife surveys using images. These images contain data that can be used to understand alterative research objectives, even years after they were originally captured. We have developed a method to measure age and morphology (body size measurements and tusk size) from survey image databases and future surveys, without the availability of a known subject distance or a scale in each image. African savanna elephants (Loxodonta africana) serve as an ideal model species to develop a non-invasive, image-based morphometric methodology: as handling these animals is particularly invasive and expensive, involving anaesthesia and because of their IUCN 'vulnerable' status. We compare in situ measurements, taken during collaring events, to tusk-to-body-size ratios, measured from the images. RESULTS: We provide evidence that relative morphological measurements, musth timing, and age of male African savanna elephants can accurately be obtained from a survey image database of over 30,000 images, taken over an 18-year period. Of the 11 tusk to body size ratios calculated, we recommend the use of two in particular for future measurement in African elephants to determine size and age: 1) tusk length to tusk diameter and 2) tusk length to body height. CONCLUSIONS: We present a practical, non-invasive measure to estimate morphometrics, including both age and tusk size from photographs, which has conservation applications to the protection of elephants and is relevant to a range of other taxa.

Loxodonta Localizer: A Software Tool for Inferring the Provenance of African Elephants and Their Ivory Using Mitochondrial DNA.

Illegal hunting is a major threat to the elephants of Africa, with more elephants killed by poachers than die from natural causes. DNA from tusks has been used to infer the source populations for confiscated ivory, relying on nuclear genetic markers. However, mitochondrial DNA (mtDNA) sequences can also provide information on the geographic origins of elephants due to female elephant philopatry. Here, we introduce the Loxodonta Localizer (LL; www.loxodontalocalizer.org), an interactive software tool that uses a database of mtDNA sequences compiled from previously published studies to provide information on the potential provenance of confiscated ivory. A 316 bp control region sequence, which can be readily generated from DNA extracted from ivory, is used as a query. The software generates a listing of haplotypes reported among 1917 African elephants in 24 range countries, sorted in order of similarity to the query sequence. The African locations from which haplotype sequences have been previously reported are shown on a map. We demonstrate examples of haplotypes reported from only a single locality or country, examine the utility of the program in identifying elephants from countries with varying degrees of sampling, and analyze batches of confiscated ivory. The LL allows for the source of confiscated ivory to be assessed within days, using widely available molecular methods that do not depend on a particular platform or laboratory. The program enables identification of potential regions or localities from which elephants are being poached, with capacity for rapid identification of populations newly or consistently targeted by poachers.

New evidence for hybrid zones of forest and savanna elephants in Central and West Africa.

The African elephant consists of forest and savanna subspecies. Both subspecies are highly endangered due to severe poaching and habitat loss, and knowledge of their population structure is vital to their conservation. Previous studies have demonstrated marked genetic and morphological differences between forest and savanna elephants, and despite extensive sampling, genetic evidence of hybridization between them has been restricted largely to a few hybrids in the Garamba region of northeastern Democratic Republic of Congo (DRC). Here, we present new genetic data on hybridization from previously unsampled areas of Africa. Novel statistical methods applied to these data identify 46 hybrid samples--many more than have been previously identified--only two of which are from the Garamba region. The remaining 44 are from three other geographically distinct locations: a major hybrid zone along the border of the DRC and Uganda, a second potential hybrid zone in Central African Republic and a smaller fraction of hybrids in the Pendjari-Arli complex of West Africa. Most of the hybrids show evidence of interbreeding over more than one generation, demonstrating that hybrids are fertile. Mitochondrial and Y chromosome data demonstrate that the hybridization is bidirectional, involving males and females from both subspecies. We hypothesize that the hybrid zones may have been facilitated by poaching and habitat modification. The localized geography and rarity of hybrid zones, their possible facilitation from human pressures, and the high divergence and genetic distinctness of forest and savanna elephants throughout their ranges, are consistent with calls for separate species classification.

CT reconstruction based 3D model of the digital cushion's blood supply in the hind foot of an African savanna elephant (Loxodonta africana).

Introduction: Foot health is crucial for elephants, as pathological lesions of the feet are a leading cause of euthanasia in captive elephants, which are endangered species. Proper treatment of the feet, particularly in conditions affecting the digits and the digital cushion, requires a thorough understanding of the underlying anatomy. However, only limited literature exists due to the small population and the epidemiological foot diseases which often precludes many deceased elephants from scientific study. The aim of this study was to provide a detailed anatomical description of the blood supply to the African elephant's hindfoot. Methods: The healthy right hindlimb of a 19-year-old deceased female African savanna elephant was examined using computed tomography. Following a native sequence, 48 mL of barium-based contrast agent was injected into the caudal and cranial tibial arteries, and a subsequent scan was performed. The images were processed with 3D Slicer software. Results: The medial and lateral plantar arteries run in a symmetrical pattern. They each have a dorsal and a plantar branch, which reach the plantar skin before turning toward the axial plane of the sole to reach the digital cushion from the proximal direction. An accurate 3D model of the arteries and the bones of the foot, a set of labeled images and an animation of the blood supply have been created for ease of understanding. Discussion: In contrast to domestic ungulates, the digital cushion of the hindlimb is supplied differently from that of the forelimb. The lack of large vessels in its deeper layers indicates a slow regeneration time. This novel anatomical information may be useful in the planning of surgical interventions and in emergency medical procedures.

Supernumerary Marker Chromosome Identified in Asian Elephant (Elephas maximus).

We identified a small, supernumerary marker chromosome (sSMC) in two phenotypically normal Asian elephants (Elephas maximus): a female (2n = 57,XX,+mar) and her male offspring (2n = 57,XY,+mar). sSMCs are defined as structurally abnormal chromosomes that cannot be identified by conventional banding analysis since they are usually small and often lack distinct banding patterns. Although current molecular techniques can reveal their origin, the mechanism of their formation is not yet fully understood. We determined the origin of the marker using a suite of conventional and molecular cytogenetic approaches that included (a) G- and C-banding, (b) AgNOR staining, (c) preparation of a DNA clone using laser microdissection of the marker chromosome, (d) FISH with commercially available human painting and telomeric probes, and (e) FISH with centromeric DNA derived from the centromeric regions of a marker-free Asian elephant. Moreover, we present new information on the location and number of NORs in Asian and savanna elephants. We show that the metacentric marker was composed of heterochromatin with NORs at the terminal ends, originating most likely from the heterochromatic region of chromosome 27. In this context, we discuss the possible mechanism of marker formation. We also discuss the similarities between sSMCs and B chromosomes and whether the marker chromosome presented here could evolve into a B chromosome in the future.

Elephant Scar Prevalence in the Kasigau Wildlife Corridor, Kenya: Echoes of Human-Elephant Conflict.

Human-elephant conflict (HEC) compromises crop security and threatens elephant conservation. Most commonly, HEC manifests as crop-foraging as elephants modify natural foraging strategies to incorporate crops. Farmers may retaliate by frightening or harming elephants, leaving scars from inflicted wounds. We assessed the prevalence and distribution of scars on the bodies of African savanna elephants (Loxodonta africana) observed in the Kasigau Wildlife Corridor (KWC), part of the Greater Tsavo Ecosystem of Kenya, where conflict is prevalent. We surmised that scars on the body are largely a result of HEC as opposed to scars on the rump or head, which we attributed primarily to elephant-elephant conflict. We hypothesized that: (1) male elephants would have more scars than females; (2) older males would be more likely to have scars than younger males; and (3) most scars would be located on the bodies of elephants. We assessed scars from a photographic catalogue of elephants from the KWC. In line with our hypotheses, male elephants were more likely to have scars than females (32% of males compared to 6% of females); older males had significantly more scars than younger males (61% compared to 24%); and the majority of scars (89%) were located on the body. Scar presence may be useful as an animal-centered indicator to estimate the prevalence and demographic patterns of HEC.

Field Propagation Experiments of Male African Savanna Elephant Rumbles: A Focus on the Transmission of Formant Frequencies.

African savanna elephants live in dynamic fission⁻fusion societies and exhibit a sophisticated vocal communication system. Their most frequent call-type is the 'rumble', with a fundamental frequency (which refers to the lowest vocal fold vibration rate when producing a vocalization) near or in the infrasonic range. Rumbles are used in a wide variety of behavioral contexts, for short- and long-distance communication, and convey contextual and physical information. For example, maturity (age and size) is encoded in male rumbles by formant frequencies (the resonance frequencies of the vocal tract), having the most informative power. As sound propagates, however, its spectral and temporal structures degrade progressively. Our study used manipulated and resynthesized male social rumbles to simulate large and small individuals (based on different formant values) to quantify whether this phenotypic information efficiently transmits over long distances. To examine transmission efficiency and the potential influences of ecological factors, we broadcasted and re-recorded rumbles at distances of up to 1.5 km in two different habitats at the Addo Elephant National Park, South Africa. Our results show that rumbles were affected by spectral⁻temporal degradation over distance. Interestingly and unlike previous findings, the transmission of formants was better than that of the fundamental frequency. Our findings demonstrate the importance of formant frequencies for the efficiency of rumble propagation and the transmission of information content in a savanna elephant's natural habitat.

Coping with heat: behavioural and physiological responses of savanna elephants in their natural habitat.

Most of southern Africa's elephants inhabit environments where environmental temperatures exceed body temperature, but we do not know how elephants respond to such environments. We evaluated the relationships between apparent thermoregulatory behaviour and environmental, skin and core temperatures for tame savanna elephants (Loxodonta africana) that were free-ranging in the hot parts of the day, in their natural environment. Environmental temperature dictated elephant behaviour within a day, with potential consequences for fine-scale habitat selection, space use and foraging. At black globe temperatures of ~30°C, elephants adjusted their behaviour to reduce environmental heat load and increase heat dissipation (e.g. shade use, wetting behaviour). Resting, walking and feeding were also influenced by environmental temperature. By relying on behavioural and autonomic adjustments, the elephants maintained homeothermy, even at environmental temperatures exceeding 40°C. Elephants clearly have the capacity to deal with extreme heat, at least in environments with adequate resources of forage, water and shade. Future conservation actions should provide for the thermoregulatory, resource and spatial needs of elephants.