Featured Research

from universities, journals, and other organizations

Behavioral Ecology: Late Breeding Female Birds Surprisingly Had More Offspring

Date:
April 6, 2007
Source:
University of Bristol
Summary:
Starting to breed late in life is a bad idea if you want to maximize the number of offspring that you produce -- or so the theory goes. But doubt has now been cast on this hypothesis -- one of the biggest assumptions in behavioral ecology -- by researchers from the universities of Bristol and Cape Town and published in Current Biology.

A green woodhoopoe.
Credit: Image courtesy of University of Bristol

Starting to breed late in life is a bad idea if you want to maximise the number of offspring that you produce - or so the theory goes.

But doubt has now been cast on this hypothesis - one of the biggest assumptions in behavioural ecology - by researchers from the universities of Bristol and Cape Town and published today in Current Biology.

Green woodhoopoes are a cooperative bird species that live in year-round, residential groups of 2-12 individuals in which only one pair breeds per season. The remaining individuals help to raise the offspring of the dominant pair, while waiting to breed themselves. Consequently, although both males and females reach reproductive maturity at one year of age, individuals may not start breeding for several years.

Using data gathered over 24 years, Dr Andy Radford and colleagues demonstrate that the females that started breeding later in life actually had more offspring than those that started earlier. Males, on the other hand, met the traditional expectation that a delayed start to breeding results in fewer offspring.

The researchers hypothesise that this surprising and apparently paradoxical situation is because females that attempt to start breeding early in life have a very high mortality rate. In contrast, females who start breeding later tend to live longer, have longer breeding careers, and thus produce more fledglings.

Dr Radford, from Bristol University's School of Biological Sciences, who is funded by the BBSRC, said: "It has been generally assumed that males and females suffer similarly from a delayed start to breeding, and many studies have investigated how non-breeding birds might mitigate this assumed cost. However, as in many facets of life, the sexes differ dramatically: although male woodhoopoes do indeed suffer if they don't start breeding as soon as possible, females do best to wait a while."

The authors postulate that the reason why young females have such a high mortality rate when attempting to breed is that they are not in as good condition as older females. Because breeding female woodhoopoes lay all the eggs and conduct all the incubation, they pay a potentially high cost.

This is exacerbated because in incubating the eggs overnight, the breeding female sleeps alone, while the rest of the group roost communally; she therefore suffers a potential thermoregulatory cost in addition to the costs associated with laying and incubation. If young females are in poorer condition than older females, they will be more likely to die as a consequence of these costs.


Story Source:

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


Cite This Page:

University of Bristol. "Behavioral Ecology: Late Breeding Female Birds Surprisingly Had More Offspring." ScienceDaily. ScienceDaily, 6 April 2007. <www.sciencedaily.com/releases/2007/04/070405122410.htm>.
University of Bristol. (2007, April 6). Behavioral Ecology: Late Breeding Female Birds Surprisingly Had More Offspring. ScienceDaily. Retrieved August 31, 2014 from www.sciencedaily.com/releases/2007/04/070405122410.htm
University of Bristol. "Behavioral Ecology: Late Breeding Female Birds Surprisingly Had More Offspring." ScienceDaily. www.sciencedaily.com/releases/2007/04/070405122410.htm (accessed August 31, 2014).

Share This




More Plants & Animals News

Sunday, August 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Experimental Ebola Drug ZMapp Cures Lab Monkeys Of Disease

Newsy (Aug. 29, 2014) In a new study, a promising experimental treatment for Ebola managed to cure a group of infected macaque monkeys. Video provided by Newsy
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Raw: Australian Sheep Gets Long Overdue Haircut

Raw: Australian Sheep Gets Long Overdue Haircut

AP (Aug. 28, 2014) Hoping to break the record for world's wooliest, Shaun the sheep came up 10 pounds shy with his fleece weighing over 50 pounds after being shorn for the first time in years. (Aug. 28) Video provided by AP
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:
from the past week

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