Friday, September 17, 2010

Different lions react in different ways to territorial intrusions.

Female_Lion

Ask a given person to name one of the four big cats, and the lion (Panthera leo) is likely to top the list. They're fierce, large, and remarkably charismatic. Throughout history, lions were integrated into the symbology of many cultures, representing such ideal traits as nobility and courage. And indeed, however much one can say such a thing, these traits can be found in lions at large. But it does no good to anthropomorphize. Lions are living organisms that fight for survival each day. To truly understand the nature of the lion requires biological research, and this research has created a vast and fascinating body of data.

Lions live in what are called 'fission-fusion' societies, in which a group separates and reforms throughout their daily activities. Lion prides comprise 1-22 adult females, their collective offspring, and a coalition of 1-9 males. These males will defend the pride against invading males, while the females will protect their offspring from infanticide by invading males, and intrusions by the females of other prides. Territory quality has been linked to reproductive success and survival, and is therefore key in the overall quality of lion lives. Because of this, when an invasion occurs, one could suggest that it would be overall better for the maximum number of pride members to respond to territorial intrusions. The more lions that respond, the better the chances of driving off a given number of invaders. However, an experiment performed by researchers from the University of Minnesota and the Australian National University suggests that the true nature of lion responses is more complex.



To simulate a territorial threat, researchers recorded the roars of a single female as well as three separate females. These roars were then played through a loud speaker within the territories of eight prides throughout Serengeti National Park and Ngorongoro Crater, Tanzania. To measure the responses of female lions, the researchers recorded the amount of time it took a given lion to reach the midpoint between the speaker and the lions ('latency'), the differences in the times it took each given lion to reach that midpoint (the 'lag time'), the order within the group that each lion reached the midpoint, and the number of backwards glances given by each lion within the group.

They then analyzed these standardized ranks to determine the degree of responsiveness to these intrusions. Some lions were consistently on the ball when a roar was played, immediately adopting an aggressive response while moving towards the playback. However, others were what were dubbed "laggards": lions that are less likely to rush towards the source of the threat. Laggards consistently slowed the approach of more active lions, causing them to pause and look back to verify that the laggard was still approaching.

lion-pride-pictures

Picture 1

Response times and actions of lions responding to territorial roars.


Interestingly, not all laggards lagged equally in every situation (though some did). Some were more likely to approach the speaker quickly when there were more invaders (and would therefore be more in need), while others lagged more when there were more invading lions relative to responders (lending an injury more likely).

Picture 2

This study suggests that though logic may dictate immediate responses to a territorial invasion, the responses of lions may vary substantially depending on the situation. Lion society is complex, and the consequences of that complexity are many. This kind of research helps unlock the secrets to lion behavior, and though they may certainly have applications to lion conservation, the more of nature's hidden facets we can uncover the better.

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