Old males vital to elephant societies

[Lisbeth]

BY UNIVERSITY OF EXETER - SEPTEMBER 3, 2020 - PHYS.ORG

Old male elephants play a key role in leading all-male groups, new research suggests.

Trophy hunters justify targeting older bull elephants on the grounds they are “redundant” in terms of breeding and hence species survival.

But the new study, by the University of Exeter, shows the oldest bulls in all-male groups are the most likely to hold leading positions when the elephants travel, potentially helping younger, less experienced followers find food and water.

The study, in collaboration with Elephants for Africa, examined the movements of male African savannah elephants (also known as bush elephants) in Makgadikgadi Pans National Park, Botswana.

“Our results challenge the assumption that older male elephants are redundant in the population and raise concerns over the removal of old bulls that currently occurs in both legal trophy hunting and illegal poaching,” said lead author Connie Allen, of Exeter’s Centre for Research in Animal Behaviour.

“We argue that selective hunting of old bulls is not sustainable.

“Past research has shown in fact that old bulls are the prime breeders (they sire the most offspring) in African elephants.

“Our findings suggest that killing them could also have detrimental effects on wider elephant society through loss of leaders who help young, newly independent males navigate in unfamiliar, risky environments.”

Pre-adolescent male African savannah elephants live in herds led by females, but between age 10-20 they leave their natal family, spending most of their time in all-male groups.

The study divided male elephants into age groups (10-15, 16-20, 21-25 and 26+) and found probability of leadership—measured by which elephant walked at the front of travelling groups—increased along with age.

“Research on benefits of older individuals in long-lived social mammals has largely focused on females in matrilineal societies where, for example, older female elephants are most effective at making decisions crucial to herd survival, and old post-reproductive female killer whales lead collective movements in hunting grounds,” said Professor Darren Croft, of the University of Exeter.

“In contrast, less is known about the role of older males as leaders in long-lived social species.


Male elephants. Credit: Connie Allen

“Our study suggests that bull elephants occupy a similar leadership role in male elephant society as old female matriarchs in breeding herds—and so they may require equal protection.”

Associate Professor Lauren Brent, of the University of Exeter, said: “This work highlights the need to examine other ways that younger males learn from experienced older males in long-lived mammals.”

Poaching, hunting and conflict with humans (such as killing by farmers) are the main causes of death among mature bull elephants, and their numbers are declining rapidly.

Older male elephants are usually targeted by trophy hunters as they have larger tusks, and often minimum ages are implemented by hunting operators.

Botswana has recently announced a decision to recommence elephant trophy hunting, and export quotas for the tusks of 400 elephants have been issued for this year.


Credit: Credit: Connie Allen/University of Exeter

“The intricacies of male elephant societies have often been ignored in management and conservation decisions with the underlying assumption that once they leave their herd they are solitary and independent,” said Dr. Kate Evans, director of Elephants for Africa and a member of the Gothenburg Global Biodiversity Centre. “

This study furthers our understanding of male elephants and the importance of older bulls, enabling more sustainable management decisions for both male and female elephants to be made.”

The paper, published in the journal Scientific Reports, is entitled: “Importance of old bulls: Leaders and followers in collective movements of all-male groups in African savannah elephants (Loxodonta africana).”

Original post: https://phys.org/news/2020-09-males-vit ... eties.html

https://conservationaction.co.za/recent ... societies/

[Lisbeth]

Based on the same report/study as the above.

The importance of adult male elephants

Posted on September 17, 2020, by Team Africa Geographic in the DECODING SCIENCE post series.


Male elephants at the Boteti River

There is a significant amount of research and knowledge surrounding the role that older female African savannah elephants play in decision-making and leading their herds, but little is understood about the contribution of older males. The assumption has generally been that these old bulls are largely redundant in terms of the overall survival of the population, but a new study conducted in Botswana has yielded results that challenge this conclusion. Instead, researchers argue that the selective harvesting of older males (through trophy hunting and illegal poaching) could have detrimental effects on wider elephant society.

The authors explain that when animals move as a coordinated group, specific individuals may consistently be observed to influence the decisions and routes taken – whether due to their hierarchical dominance, a bolder temperament or advanced age. In species with a relatively long life expectancy, such as elephants or killer whales, older individuals have been seen to respond more appropriately to a change in environment, as well as mobilising in response to potential threats. While research into this area has tended to be mostly female-focused, there is no reason why there should be a sex-based distinction in the accumulation of knowledge over time, nor is it necessarily the case that males do not have the potential to occupy socio-cognitive roles similar to the females of the species – acting as “repositories of ecological knowledge”.


Male African elephants congregate at hotspots of social activity on the Boteti river in Makgadikgadi

In social animals, males are typically the dispersing sex and, therefore, are assumed to be replaceable. In elephants, the males tend to leave their natal herds between 10-20 years of age, roaming vast distances and often forming temporary associations with other males of various ages. In associating with older males, the study explains, adolescent bulls could benefit from decades’ worth of experience in utilising their environment effectively while negotiating potential risks such as conflict with people.

The study was conducted in the Makgadikgadi Pans National Park – where male elephants account for some 98% of the elephant sightings. The researchers focussed on all-male groups travelling on pathways to and from the Boteti River. The results indicate that young elephants show a significant preference for travelling in groups and that mature adult males were more likely to lead these group movements. These findings applied throughout the year in both the wet and dry seasons, suggesting that these mature bulls offer a signification contribution to elephant society, regardless of the season. The researchers found little evidence that size (particularly stride length) influenced the positioning of individual elephants in the group.


Male elephants socialising at the Boteti River

This observed pattern of movement is in direct contrast to that of a breeding herd, where the matriarch will initiate movement and direction but generally move to the back of the group where she can monitor the members of the herd. The process appears to be more passive in male leadership, with the older elephant making decisions and the younger members of the group choosing to follow them. It is, however, an essential role in the male society of elephants, particularly when leading young males between crucial resources such as water.


Young adolescent bull elephants sparring at the Boteti River

While they represent the minority in elephant populations, bull elephants are targeted by trophy hunters and poachers due to their larger body sizes and tusks. The researchers suggest that their findings regarding the leadership of older males during collective movement complements other research into the importance of mature bulls in all-male societies. The study expresses concern that targeting these old male animals in trophy hunting could disrupt these all male-societies, as well as the “inter-generational flow of information concerning decades of accumulated ecological knowledge, such as effective navigation and location of critical resources”. Instead, the authors suggest, the role of mature bulls should be recognised as similar in male groups as that of a matriarch in a breeding herd and, as such, they should be afforded equal protection.

The full study can be accessed here: “Importance of old bulls: leaders and followers in collective movements of all-male groups in African savannah elephants (Loxodonta Africana)”, Allen, C., Brent, L., et al (2020), Scientific Reports


A young adolescent next to an older bull in the Makgadikgadi Pans National Park

[Alf]

Awesome post