Featured Research

from universities, journals, and other organizations

Bats change strategy when food is scarce

Date:
September 4, 2014
Source:
University of Bristol
Summary:
Bats could be more flexible in their echolocation behavior than previously thought, according to a new study into the foraging techniques of the desert long-eared bat. Gleaning bats usually have long ears for the detection of faint sound cues and low wing loading to allow them to carry heavy loads -- features that increase drag and are linked to slower flight. So why would bats adapted to one foraging mode (gleaning), adopt another (hawking)?

Echolocating bats have historically been classified into two groups: 'loud' aerial hawkers who catch flying insects on the wing and 'whispering' gleaners that pick up prey from the ground. While some bat species can forage in multiple ways, others have limited flexibility in the amplitude of their echolocation calls.

Dr Talya Hackett and colleagues studied the desert long-eared bat (Otonycteris hemprichii), said to be a passive 'whispering' gleaner that picks up ground-dwelling invertebrates, such as scorpions, from the desert floor.

Using an acoustic tracking system, the researchers recorded the bats flying at four different foraging and drinking sites in the Arava and Judean Deserts in Israel. They then compared the bats' flight height, flight speed, call duration, pulse interval and source levels with those of other gleaning bats.

Differences were found in all these variables, with the most striking being the source levels: bats were recorded calling at an average of 119 decibels, akin to a 747 jet on take-off, when around 75, akin to a car engine, is more usual when gleaning (though these sounds occur at a high frequency, beyond the range of human hearing). Analysis of the bats' faeces also indicated that their diet included prey species capable of flight, such as flies, moths, and beetles. This suggests that the bats switched from passive gleaning to capturing airborne insects (aerial hawking).

Dr Hackett said: "Although whispering bats have been known to opportunistically catch insects on the wing, this doesn't appear to be the case here. All the bats' calls we recorded were loud and we didn't observe any low flying search tactics which suggests that the bats were exclusively aerial hawking."

Gleaning bats, like the ones in this study, usually have long ears for the detection of faint sound cues and low wing loading to allow them to carry heavy loads -- features that increase drag and are linked to slower flight. So why would bats adapted to one foraging mode (gleaning), adopt another (hawking)?

Co-author Dr Marc Holderied said: "Changes in environmental conditions or prey availability could explain this change in the bats' behaviour. We studied them towards the end of an exceptionally hot and dry summer so it's likely the usual prey animals were scarcer: desert scorpions, for example, become more inactive during dry conditions. As a result, the bats might have entered different habitats with artificial irrigation or attacked different prey, adopting a different foraging mode when their typical prey was scarce."

Not only did the desert long-eared bat switch foraging modes but it also drastically altered both its call and flight behaviour when doing so. The variability in source levels recorded was the most extensive change seen in any bat species, indicating that perhaps bats are more flexible in their echolocation behaviour than previously understood.


Story Source:

The above story is based on materials provided by University of Bristol. Note: Materials may be edited for content and length.


Journal Reference:

  1. T. D. Hackett, C. Korine, M. W. Holderied. A whispering bat that screams: bimodal switch of foraging guild from gleaning to aerial hawking in the desert long-eared bat. Journal of Experimental Biology, 2014; 217 (17): 3028 DOI: 10.1242/%u200Bjeb.100362

Cite This Page:

University of Bristol. "Bats change strategy when food is scarce." ScienceDaily. ScienceDaily, 4 September 2014. <www.sciencedaily.com/releases/2014/09/140904111227.htm>.
University of Bristol. (2014, September 4). Bats change strategy when food is scarce. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2014/09/140904111227.htm
University of Bristol. "Bats change strategy when food is scarce." ScienceDaily. www.sciencedaily.com/releases/2014/09/140904111227.htm (accessed October 20, 2014).

Share This



More Plants & Animals News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Rare Lion Cubs Make Debut at Belgrade Zoo

Raw: Rare Lion Cubs Make Debut at Belgrade Zoo

AP (Oct. 17, 2014) Two white lion cubs were born in Belgrade zoo three weeks ago. White lions are a rare mutation of a species found in South Africa and some cultures consider them divine. (Oct. 17) Video provided by AP
Powered by NewsLook.com
The Best Foods To Boost Your Mood

The Best Foods To Boost Your Mood

Buzz60 (Oct. 17, 2014) Feeling down? Reach for the refrigerator, not the medicine cabinet! TC Newman (@PurpleTCNewman) shares some of the best foods to boost your mood. Video provided by Buzz60
Powered by NewsLook.com
Sweet Times for Hard Cider Makers

Sweet Times for Hard Cider Makers

AP (Oct. 16, 2014) With hard cider making a hardcore comeback across the country, craft makers are trying to keep up with demand and apple growers are tapping a juicy new revenue stream. (Oct. 16) Video provided by AP
Powered by NewsLook.com
Meet Garfi the Angry Cat

Meet Garfi the Angry Cat

Buzz60 (Oct. 16, 2014) Garfi is one frowny, feisty feline - downright angry! Ko Im (@koimtv) introduces us to the latest animal celebrity taking over the Internet. You can follow more of Garfi's adventures on Twitter (@MeetGarfi) and Facebook (Garfi). Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins