Walk This Way! Experienced Female Elephants Show Their Naïve Younger Relatives How to Play the Mating Game

If you’re a female elephant, there’s a right way and a wrong way to play the mating game. To maximize your chances of reproductive success, it’s best to pair up with a dominant bull elephant in musth, a state of heightened arousal in which testosterone courses through the bull’s body, increasing both his sex drive and his aggression. A high-ranking musth elephant not only makes the fittest mate, but he can protect you by scaring off the less desirable younger males who would otherwise chase you around.

An experienced female knows this well, and plays the game accordingly. When she goes into heat – or oestrus – and attracts male suitors through chemicals in her urine, she gives impressive senior bulls the green light by holding her tail high, walking with an exaggerated gait, and exchanging affectionate trunk caresses. Lower-ranking young males don’t fare so well. She actively avoids them and, to the extent they aren’t chased off by her favored partner, she’ll often spurn their advances by running away. (Little known fact: female African elephants can typically outrun male ones.)

It’s not so easy for a young female entering oestrus for the first time. She sometimes runs from the larger musth males, who can weigh more than twice as much as her, and not infrequently ends up consorting with a series of younger, lesser males. This can lead to unfortunate results, especially when you consider that an elephant pregnancy lasts 22 months.

Now, though, there’s evidence that experienced females may help their younger relatives in sorting through the confusing tangle of elephant sexual dynamics. These helpful older elephants – sisters, aunts, mothers, and matriarchs – appear to simulate oestrus in order to show their innocent family members how to act, enabling them to avoid the pitfalls of poor mating choices.

If I said you had a beautiful trunk, would you hold it against me? (photo: WildlifeDirect, Dzanga Forest Elephants)

After hearing anecdotal accounts of this behavior, a team led by Lucy Bates of the University of St. Andrews decided to dig deeper by taking advantage of an invaluable resource – a comprehensive multi-decade database cataloging the daily life activities of 2,200 Amboseli elephants compiled by Cynthia Moss, Joyce Poole, and other researchers as part of the Amboseli Elephant Research Project (AERP).

Bates and her colleagues systematically combed through 28 years of detailed AERP records and located all occasions on which an observer had concluded that an identifiable elephant was in oestrus (based on postural and behavioral changes in females, interactions with males, etc.). In total, they found descriptions of 999 oestrus events, slightly less than 10% of which (98 events) recorded two or more members of the same elephant family displaying simultaneous oestrus behavior.

Next, the researchers cross-referenced these accounts with AERP demographic records to find any that must have been “false” oestrus events, which they defined as oestrus-like behavior by a female who was either already pregnant, in a state of lactation-induced infertility, or senescent (which they deemed to be the case if she was over 50 years old, had not given birth to any calves during the prior five years, and had no subsequent calves).

They discovered that, while false oestrus behavior was relatively rare (occurring only 19 times and representing only about 2% of all recorded oestrus events), its timing was fascinating. Very often, it occurred just when a young relative was coming into oestrus for the first time.

Even though simultaneous oestrus behavior had been recorded less than 10% of the time, over half of the false oestrus events (10/19) clearly occurred at the same time as the true oestrus of a young female family member who had never given birth. Further, subsequent birth records confirmed that on four additional occasions a false oestrus event occurred during the month that a young relative conceived her first calf (that is, the young female must have been in oestrus at the time, even though it wasn’t specifically called out in the AERP database). Finally, one of the false oestrus events occurred simultaneously with the genuine oestrus of a female relative who had given birth before. Thus, the large majority of the false oestrus events – 15 of 19 – coincided with true oestrus events, in most cases, the first oestrus of a young relative. (Moreover, note that the balance of the false oestrus events could also have coincided with true ones if, as in the four cases described above, the true oestrus event simply had not been observed or recorded in the AERP database.)

The researchers then examined various hypotheses that might explain the false oestrus behavior:

  • That false oestrus merely results from hormonal changes and has no functional purpose;
  • That it somehow induces sexual receptivity in the simulating female, thereby increasing her own chances of successfully reproducing;
  • That it indirectly benefits the simulating female by providing a young family member with increased access to suitable males (this type of indirect benefit is known as an inclusive fitness benefit); or
  • That it indirectly benefits the simulating female by encouraging a confused younger relative to engage in more suitable oestrus behavior (another potential example of inclusive fitness).

They quickly rejected the all but the final hypothesis. For one, hormonal changes couldn’t adequately explain either the observed patterns (false oestrus occurred in both pregnant and non-pregnant females, as well as during all stages of pregnancy) or the higher-than-expected coincidence of false oestrus with the genuine oestrus events of inexperienced relatives. Second, it was clear that the simulating elephants weren’t improving their own reproductive success: in 14 of 19 cases the simulating the female was already pregnant, and in four others she was senescent. Third, AERP records revealed that false oestrus behavior had no impact on the number of available males, the relative percentage of males who were in musth, or the amount of sexual activity engaged in by inexperienced female.

Ultimately, the researchers concluded that:

Further data is required to confirm or reject the hypothesis that this behaviour functions to teach the young, naïve females, but we suggest that it remains the only viable possibility based on the current analyses.

In particular, they noted that additional research and data collection was necessary to explain the instances in which false oestrus didn’t appear to coincide with an inexperienced relative’s oestrus as well as to support the notion that inexperienced females were able to correct substandard mating behavior after they were shown what to do by their older relatives.

In the meantime, though, you’d be well advised to stay away from those frivolous young guys and find yourself a dashing older bull who knows his way around the herd.

_____

ResearchBlogging.orgBates, L., Handford, R., Lee, P., Njiraini, N., Poole, J., Sayialel, K., Sayialel, S., Moss, C., & Byrne, R. (2010). Why Do African Elephants (Loxodonta africana) Simulate Oestrus? An Analysis of Longitudinal Data PLoS ONE, 5 (4) DOI: 10.1371/journal.pone.0010052.

About these ads

The Wisdom of the Aged: Matriarch Elephants Lead with Experience

As many people know, African elephants (Loxodonta africana) live in complex matrilineal societies, with closely-knit family groups led by a matriarch who is typically the oldest and largest female in the family. In order to appreciate the importance of these matriarchs, it may help to first consider a traditional Japanese folktale:

Once there was an arrogant young village lord who, deciding that old people were useless, banished them to the mountains to die. Although the villagers were distressed, they obeyed rather than face severe punishment. One young farmer couldn’t bear to follow this cruel decree, though, and hid his aged mother away in a safe and secret room.

Several years later, an invader arrived, announcing that he’d spare the village only if three tasks could be performed. First, he must be presented with a box containing one thousand ropes of ash. Next, a silk thread must be drawn through a small hole that bent seven times along the length of a log. Finally, he must be given a drum that sounded without being beaten.

In each case, the village lord offered rewards, cajoled and threatened the townspeople, but nobody knew what to do; all were in despair. The tasks all seemed impossible. Each time, though, the farmer asked his mother and she knew the answer: soak ordinary rope in salt water before burning it; tie the silk thread to an ant at one end of the hole and place sugar at the other; put a bumblebee in a drum and it will buzz as it tries to escape. The village was spared.

Ultimately, the lord finds out that they have all been saved by the wise old mother, and from that time on elders in the village are revered.

Shifting scenes now from the mountains of long-ago Japan to the plains of today’s Africa, it turns out that older matriarch elephants are much like the heroic old Japanese mother – they are the ones with the answers, the ones that can save their fellow elephants from outside threats with the wisdom they have accumulated through experience.

Listen to your Grandmother! (image copyright ElephantVoices)

As we know from the decades of observation and research performed by Cynthia Moss and her colleagues in Kenya and Tanzania, matriarch elephants act as group leaders, holding together their families and providing behavioral guidance during times of crisis. Many observers believe that the oldest matriarchs – those with the most experience and greatest ecological knowledge – make the best decisions, but until recently it has proved to be difficult to quantify the relevant skills in a manner conducive to experimental testing.

In a March 2011 paper published online in the Proceedings of the Royal Society B, however, a team of scientists led by Karen McComb of the University of Sussex reported on a clever set of experiments that tested whether older Amboseli National Park matriarchs were better than their younger counterparts at assessing the perceived threat posed by various lion roar recordings.

While African elephants are able to fend off most natural predators, they have to watch out for lions, who occasionally prey upon younger calves. Also, even though lionesses perform the, ahem, lion’s share of the hunting for the pride, male lions actually pose a greater threat to elephants. Male lions, despite their generally well-deserved reputation for laziness, are, on average, half again as large as females and much stronger, giving them a better chance of overpowering a vulnerable young elephant.

Accordingly, the researchers assembled lion “playbacks” in four separate categories – single female roars, single male roars, three female group roars and three male group roars – which they then played to 39 elephant family groups over a period of slightly more than two years. Because of the extensive demographic information compiled by the Amboseli Elephant Research Project, they knew the age of the matriarch in each of the 39 families.

After playing the different roars, the researchers analyzed video of the elephants’ responses, focusing particularly on the behavior of the matriarchs. They documented specific defensive reactions, including prolonged listening to the roars, whether the family bunched around the matriarch after hearing the roars, the speed and intensity of any bunching behavior, and whether the matriarch changed her direction and moved toward the source of the playback.

Here are two brief videos, one showing an elephant family reacting to lion roars and the other narratively describing the reactions as reflected in still images:

After recording all of the responses, the research team performed statistical analyses and sorted their results by matriarch age. They found that, while matriarch age did not have an impact on how the elephants reacted to varying number of lions (all elephant families consistently ratcheted up the intensity of their response when the number of lions roaring went from one to three), it did have a strong impact on the elephants’ response to the more serious threat presented by male lion roars, with male roars leading to more prolonged listening and intensive defensive bunching in families led by older matriarchs.

As the researchers put it:

Our work provides the first direct experimental evidence that older matriarchs are in fact able to make better decisions when faced with ecological challenges — in this case, the presence of dangerous predators. It thus bridges an important gap between theoretical predictions about how knowledge might be expected to affect leadership and empirical studies, which to date have been largely confined to observational accounts.

Based on these findings, I’m quite confident that the older matriarchs will do quite well on their next set of tasks involving burning ropes, crooked logs and drums. Now, if only that was enough to keep humans from invading their villages….

_____

ResearchBlogging.org

The Japanese folktale can be found, among other places, in The Wise Old Woman/retold by Yoshiko Uchida; illustrated by Martin Springett. ISBN: 0689505825.

McComb, K., Shannon, G., Durant, S., Sayialel, K., Slotow, R., Poole, J., & Moss, C. (2011). Leadership in elephants: the adaptive value of age Proceedings of the Royal Society B: Biological Sciences, 278 (1722), 3270-3276 DOI: 10.1098/rspb.2011.0168.

Elephant Insight

With each passing week, it seems like we’re finding out more and more about how smart elephants are. Now, in addition to their other cognitive abilities, it turns out that elephants can have “aha!” moments of insight as they face puzzling dilemmas. [No, not a-ha as in 1980s synth-pop from Norway; if you’re looking for an early MTV a-ha moment, you should probably go here!]

Elephants have the largest brains and the greatest volume of cerebral cortex of all terrestrial mammals. They live in elaborate matriarchal societies that include long-lasting relationships, close family bonds, and complex social groupings that change over time. They squabble and negotiate with each other over travel directions; they flirt, show empathy towards one another and solve problems cooperatively. They are one of the very few animals that can recognize themselves in mirrors (more about self-recognition testing here and here). True to their reputations, they have terrific memories, are adept at making and using tools, are logical thinkers, and even appear to mourn their dead in a “ceremonial” manner suggesting they may have a real awareness of the separate lives and experiences of other elephants.

Until now, however, on the few occasions when elephants have been tested for insightful problem solving abilities, they have been performed poorly. In these previous tests, the elephants failed to use their trunks in order to gain access to food treats that had been placed just beyond reach (for example, by using a stick grasped in the trunk to reach out for the food, or by pulling on a retractable cord with their trunks in order to reel in the food reward).

In a paper just published online on August 18th in PLoS ONE, a research team led by Preston Foerder and Diana Reiss of the City University of New York reported on its own revelation that led to a breakthrough in tests for elephant problem-solving insight. The researchers surmised that the problem with prior testing was not that elephants were incapable of insight, but rather that the tests had called for the elephants to act in ways that undermined their ability to use their trunks as effective sense organs during the task:

We believe that the problem in previous studies has been in treating the elephant trunk as a grasping appendage analogous to a primate hand. Although the trunk is a highly manipulable appendage, in food foraging its function as a sensory organ may take precedence. The elephant has an extraordinary sense of smell, and the tip of the trunk is as highly enervated as a human fingertip…. When a stick is held in the trunk, the tip is curled backwards and may be closed, prohibiting olfactory and tactile feedback…. We posit that previous failures to observe insightful problem solving in elephants is not indicative of a lack of cognitive ability but rather is due to the reliance on problem solving tasks that precluded the use of the trunk as a sense organ.

To address this issue, the researchers set up a series of experiments designed to allow elephants to keep their trunks free while facing problem-solving challenges. They tested three Asian elephants (Elephas maximus), two adult females and a 7-year-old juvenile male, at the Smithsonian National Zoo in Washington, DC, with the juvenile male, Kandula, soon emerging as the rock star problem-solver.

In the first experiment, the researchers dangled enticing fruit rewards from a cable they had placed across the elephant yard, including from positions that were just beyond trunk-reach. After leaving a large plastic cube and some other objects in the yard, they let Kandula into the yard for sessions to see whether he would figure out how to obtain the dangling food reward. While Kandula had previously played with the cube as an enrichment toy, he had no prior training in pushing large objects or in standing on them to reach for things.

During an initial six sessions, each lasting 20 some minutes, Kandula showed interest in the food dangling above his reach, played with the cube, moved it on several occasions, and once even stood on it briefly, but never tried to reach out for anything while standing on the cube.

Then, during the seventh session, Kandula suddenly had his moment of epiphany: he rolled the cube into position beneath the hanging food, stood on the cube with his front two feet, stretched out his trunk, and grabbed his prize.

Kandula - Insightful and Now Less Hungry Elephant

From then on, Kandula was off to the races. In the next session, he not only rolled the cube over and stood on it to reach the fruit again, he also started using the cube as a tool to reach other objects: e.g., standing on it to explore the inside of an enrichment object and, after rolling it to the edge of the yard, using it as a platform to reach for blossoms on an overhanging tree branch.

Moreover, Kandula showed he was able to apply his insight to new situations. For example, in a second experiment, the researchers used the same general setup, but began moving the cube around from place to place, including behind fences and in locations that Kandula couldn’t see as he entered the yard. In each case, Kandula found the cube and rolled it over to capture his food reward. Here’s a video of Kandula retrieving the cube from behind a fence:

Next, the researchers replaced the cube with a large tractor tire – in three of four sessions Kandula used the tire as a tool, rolling it to the proper place, and then standing on it to obtain the food reward.

In a final experiment, the researchers replaced the cube and the tire with a variety of other objects, including large plastic balls, discs, cones, a barrel lid and three cutting boards that would have to be stacked to form a platform for Kandula to reach the food. While Kandula didn’t stack all three boards (he did stack two, though), he experimented with various approaches such as standing with one foot on separate objects. Ultimately, he reached the food by standing on a plastic ball, a solution that surprised the researchers since he had never placed his weight on a similarly unstable platform before.

So, to summarize, Kandula demonstrated sudden insight – using a tool to solve a problem in a novel and spontaneous fashion, without evidence of prior trial and error learning. Further, he showed that he could repeat, transfer and extend his technique in subsequent sessions.

If you’re an elephant, please feel free to give yourself a pat on the back. Job well done!

_____

1Foerder, P., Galloway, M., Barthel, T., Moore, D., & Reiss, D. (2011). Insightful Problem Solving in an Asian Elephant PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0023251.

Asian Elephant Social Networkers

In a terrific new study in this month’s BMC Ecology1, a team of researchers led by Shermin de Silva of the University of Pennsylvania Biology Department has published the results of extensive, multi-year research regarding the social dynamics of a population of Asian elephants (Elephas maximus) at Uda Walawe National Park in Sri Lanka. The researchers studied 286 adult female elephants from September 2006 to December 2008, observing the social relationships they formed on a one-to-one basis, in small groups, and at the overall population level.

While group social behavior in African savannah elephants (Loxodonta africana) has been studied extensively, this new research is the first detailed, quantitative study of a wild Asian elephant population over such a lengthy time period … and what the researchers found was quite surprising.

You spend all your time social networking! First do your homework, then you can go on Facebook (photo credit: HelpElephants.com)

Prior less comprehensive studies had suggested that Asian elephants form less complex social networks than do African savannah elephants, with Asian elephants forming smaller and looser social groups based primarily on mother/daughter bonds, and rarely if ever involving relationships between unrelated females. In this in-depth longitudinal study, though, a different, more nuanced, portrait of Asian elephant society emerged.

Although, on any given day, the researchers would see only small groups of elephants that didn’t appear to interact extensively, over time, individual elephants formed larger social units that could be remarkably stable across years, even while associations among such units varied quite a bit across seasons.

One-to-One Relationships (Dyads)

The researchers started out by measuring how much time pairs of adult females spent together and found that, at a high level, the frequency of their associations was highly correlated across all five seasons in the National Park (Sri Lanka has a highly seasonal environment, with two separate monsoon seasons, two dry seasons, and a transitional season) – that is, pairs who associated in one season tended to associate in all seasons, and those who did not associate in a given season weren’t likely to associate at all.

Yeah, let's just hang and make nice for now, then we'll hit the rice paddies when nobody's looking! (photo credit: EleAid.com)

In studying one-to-one relationships, the researchers turned their attention to 51 “core” elephants who they thought would provide particularly good data, since these elephants were observed frequently and during all seasons of the year. These elephants formed a total of 478 pair relationships, which the researchers divided out statistically as follows:

  • A total of six (1.3%) of the pairings were “strong” and stable relationships, as measured by the relative percentage of time these pairs spent together during all seasons. Nine of the elephants (17.6%) participated in relationships in this category.
  • A total of 433 (90.6%) of the pairings were “temporary,” with the association peaking during a single season (most of the peaks were in either the transitional or dry seasons). All 51 of the elephants had at least one relationship that fell into this category.
  • A total of 39 (8.2%) of the pairings were “cyclical,” with the associations peaking in frequency during the two dry seasons (interesting, the researchers did not find relationships where the peaks were during the two wet seasons). Thirty two (62.7%) of the elephants had relationships that were cyclical.

Next, the researchers analyzed whether the identities of an elephants’ preferred companions changed over time. Overall, they found that the elephants spent slightly more than 20% of their time with their long-term companions (the top five companions over five seasons) and slightly more than 30% of their short-term companions (the top five for the current season). On an individual level, there was quite a bit of variation: eight (15.7%) of the elephants maintained 4 to 5 of their top five companions for all five seasons, while 16 (31.4%) completely changed their top-five companions during the study.

The researchers cite the example of two elephants, Kamala and Kanthi, who spent nearly all their time together – they were part of the “K” unit (Kamala, Kanthi, Karin, Kavitha and Kalyani, but no Kardashians) that was particularly close – and contrasted this kloseness to an individual named “471” that had few stable companions. (I wonder if this was due to distress over only receiving a number for a name.)

Additionally, the researchers noticed that the elephants who had the most relationships tended to form weaker bonds with each individual partner, whereas those with relatively few pairings tended to spend a relatively large amount of time with each of their companions.

Hmm, these elephants are beginning to sound quite a bit like people…

Small Group Associations (Ego Networks)

At the next level up, the researchers studied so-called “ego networks,” social networks consisting of an elephant and all of the other individual elephants with whom she associated at least once. The researchers focused on 88 of the adult females who they observed in every season, and calculated five measurements for each: (1) the number of her direct companions, (2) the number of ties between the direct companions, (3) the total number of potential ties between each of these direct companions, (4) the ratio of actual to potential ties, and (5) the number of individuals within two degrees of separation of the subject (number of friends plus number of “friends of friends”).

(Note that, assuming at least one of the researchers is within five degrees of separation of Kevin Bacon, this would mean that the entire ego network would be within seven degrees of separation of Kevin Bacon.)

Without getting into the full statistical analysis, the researchers’ principal conclusion was that:

[W]hile a subject’s direct companions do change over time, she has a few that are almost always present; even those that are not present continuously may have been companions in previous seasons. Thus, individuals maintain long-term relationships with others even though they may be apart for one or several seasons and [the amount of time spent together is small].

In other words, the elephants remember their friends and reestablish their relationships even after having been apart for long periods.

Population Level

Finally, the researchers looked at the social structure of the entire population. They found that the elephants in the overall popular had an extensive and well-connected social network, and that the distinct social units within the population were two to three times larger than had previously been seen in the field. Moreover, they observed that many of the social units maintained their integrity across seasons, even as individuals switched units and the connections between the units changed.

For those of you who like to look at dot patterns, below is a colorful series of diagrams depicting the connections between elephants, measured at different societal levels and during different seasons (T1 is the transitional season, D1 and D2 are the dry seasons, and W1 and W2 are, you guessed it, the wet seasons):

Figure 5 from Research Paper

Recap

While the strength of the associations among these Asian elephants (as measured by percentage of time that individuals spent together) is generally a good bit lower than that of the associations among African savannah elephants, most of these elephants had a few strong ties as well as consistent ties that they maintained over several seasons. Further, the Asian elephants were hardly asocial – while their mix of companions did fluctuate over time, they often returned to a subset of preferred companions.

Moreover, through their years of observation and statistical analysis of the elephants at the population level, the researchers found that the elephants’ social units were much larger than had been observed in prior studies, and that these social units were more stable across the years than were the companions of individual elephants.

The researchers speculated that one reason for the surprising findings is that the elephants stay in touch in ways that are hard for humans to detect, allowing the elephants to maintain bonds and relationships that we fail to observe. For example, elephants can communicate acoustically over great distances, and often use scent to follow one another’s paths at night (and, for that matter, even when the other elephants would be in plain sight, at least from the human perspective).

Finally, the researchers are planning to perform a detailed genetic study of the population in order to analyze the degree to which relatedness impacts the social organization of Asian elephant society. We’ll be waiting!

_____

1de Silva, S., Ranjeewa, A., & Kryazhimskiy, S. (2011). The dynamics of social networks among female Asian elephants BMC Ecology, 11 (1) DOI: 10.1186/1472-6785-11-17.

Elephant Negotiations

What better way to kick off a blog about animal wisdom than with a shout out to the ponderous and pulchritudinous pachyderm? Rest assured that there will be many more posts about these lovably large animals, but for now I wanted to call attention to a recent article in the UK Daily Mailthat provides some fascinating color regarding elephants’ complex social systems.

African Elephants (photo credit: World Wildlife Federation)

The article, reporting on nearly 40 years of continuous study by Cynthia Moss and her team of researchers at the Amboseli National Park in Kenya, describes the many ways in which elephants engage in sophisticated communications through body language and sound. Read the article and check out the handy graphics for insight into how elephants flirt (hey, big guy…), greet each other by entwining trunks, invite others to play, show empathy by wincing at each other’s pain, and even squabble over directions:

Negotiations over directions often begin with a common signal known as the ‘let’s go’ rumble. The elephants then engage in lengthy exchanges until a consensus is reached and the herd moves off in the chosen direction. Phyllis Lee, of Stirling University, Scotland – co-editor of The Amboseli Elephants, a new book revealing the research – said elephants can take up to an hour discussing which way to go. ‘It’s wonderful to watch and a real process of negotiation,’ she said.

The one quibble I have with the article is its assertion that the elephants’ social system is “remarkably similar to that of humans.” As we sit here in California facing another budgetary impasse and look forward to similar fun to be had in Washington, D.C., this summer, it seems to me that we should invite in the elephants to show us humans a “real process of negotiation” that leads to a consensus in an hour. Of course, the politicians might then need to haul out their shovels and spend another hour or so cleaning up, but that’s another story.

_____

1The Mail Online, “Not such a Dumbo: How elephants flirt, argue and have feelings just like humans,” June 6, 2011.

%d bloggers like this: