Reduced older male presence linked to increased rates of aggression to non-conspecific targets in male elephants

This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this recordMales in many large mammal species spend a considerable portion of their lives in all-male groups segregated from females. In long-lived species, these all-male groups may contain individuals of vastly different ages, providing the possibility that behaviours such as aggression vary with the age demographic of the social environment, as well as an individual’s own age. Here, we explore social factors affecting aggression and fear behaviours in non-musth male African elephants (Loxodonta africana) aggregating in an all-male area. Adolescent males had greater probabilities of directing aggressive and fearful behaviours to non-elephant targets when alone compared to when with other males. All males, regardless of age, were less aggressive toward non-elephant targets, e.g., vehicles and non-elephant animals, when larger numbers of males from the oldest age cohort were present. Presence of older males did not influence the probability that other males were aggressive to conspecifics or expressed fearful behaviours toward non-elephant targets. Older bulls may police aggression directed toward non-elephant targets, or may lower elephants’ perception of their current threat level. Our results suggest male elephants may pose an enhanced threat to humans and livestock when adolescents are socially isolated, and when fewer older bulls are nearby.Leverhulme TrustExplorers ClubWilderness Wildlife TrustElephants for AfricaIDEAWIL

Importance of old bulls: Leaders and followers in collective movements of all-male groups in African savannah elephants (Loxodonta africana)

This is the final version. Available on open access from Nature Research via the DOI in this record.Due to the sensitive nature of reporting on elephant locations and numbers, the data that support the findings of this study are available on reasonable request from the corresponding author.In long-lived social species, older individuals can provide fitness benefits to their groupmates through the imparting of ecological knowledge. Research in this area has largely focused on females in matrilineal societies where, for example, older female African savannah elephants (Loxodonta africana) are most effective at making decisions crucial to herd survival, and old post-reproductive female resident killer whales (Orcinus orca) lead collective movements in hunting grounds. In pathways in Makgadikgadi Pans National Park, Botswana, we found that the oldest males were more likely to lead collective movements. Our results challenge the assumption that older male elephants are redundant in the population and raise concerns over the biased removal of old bulls that currently occurs in both legal trophy hunting and illegal poaching. Selective harvesting of older males could have detrimental effects on the wider elephant society through loss of leaders crucial to younger male navigation in unknown, risky environments

Field evidence supporting monitoring of chemical information on pathways by male African elephants

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordData Statement: Due to the sensitive nature of reporting on African elephant locations and numbers, the data that support the findings of this study are available on reasonable request from the corresponding author.When animals move along well-established pathways, sensory cues along the path may provide valuable information concerning other individuals that have used the same route. Yet the extent to which animals use pathways as sources of public social information is poorly understood. Here we quantify wild African savannah elephants (Loxodonta africana) responsiveness to olfactory information along natural elephant pathways, habitual routes that link predictable critical resources in the environment. By monitoring the behaviour of elephants travelling on pathways in a predominantly male study population, we found that elephants were highly olfactorily responsive to pathway substrate. Lone travellers were more responsive than elephants travelling in groups, suggesting elephants without social companions may be more dependent on olfactory cues on pathways during navigation. Furthermore, by experimentally presenting olfactory cues on pathways we provide evidence that male African elephants exhibit focused olfactory responses to urine cues of same-sex conspecifics for at least 48 hours from 3 time of deposition, and that urine from adult elephants was more likely to elicit vomeronasal system responses compared to subadult urine. African elephants may therefore potentially be able to discern the age and maturity of individuals they can expect to encounter in the environment from remote urine cues on pathways. We suggest elephant pathways act as a public information resource, assisting navigating elephants via the deposition of urine and dung by previous travellers on the route. These results could help inform elephant management, which may manipulate olfactory information on pathways in high human-wildlife conflict areas, or could use olfactory urine cues to improve the efficiency of corridors that link protected areas for elephants.Leverhulme TrustExplorers Club Exploration FundWilderness Wildlife TrustIDEAWIL

Hepatic cysts and hyperechogenicities: Perinatal assessment and unifying theory on their origin

The authors report their experience with the perinatal diagnosis of six cases of hepatic cyst and six of liver hyperchogenicities. The in utero diagnosis of hepatic cysts was difficult when the cysts were large or subhepatic. A precise diagnosis was sometimes achieved only after surgery. Small intraparenchymal cysts tended to regress spontaneously. Liver hyperechogenicities were diffuse or localized. They were unrelated to liver infection, tumors, meconium peritonitis or biliary tract anomaly. Both entities could be related to vascular disruption phenomenon (VDP) in which structural anomalies result from damage to normal development of embryonic or fetal vessels with anomalies of perfusion to the developing organs. The consequences of VDP to the liver are variable depending on the time and duration of the phenomenon. Localized infarct or ischemia can fibrose or calcify leading to segmental hyperechogenicities. Necrosis with tissue reabsorption can be the origin of some (sub)hepatic cysts. When such anomalies are detected there should be a careful study of the placentation, and a search for potential associated anomalies should be undertaken. © 1994 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe