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a male bird feeding a baby bird in a tree.
Male Tree Swallow feeding a baby swallow. Courtesy of Steve Byland and Flickr.
The probability of high paternity or low paternity does not impact how often the male visits the female nor when he visits her in the egg laying cycle.

How yellow-headed blackbirds attract mates

In the yellow-headed blackbird ( Xanthocephalus xanthocephalus ), males attract mates by adopting broods of others’ offspring. In this species, females choose where to nest based on the number of females living on the territory and the number of active nests. The more females with active nests on a territory, the more resources the territory must have and the safer it must be from predators. These factors will lead females to nest in the same area. Replacement males, thus, may be able to attract new females ready to settle if they accept the presence of unrelated offspring in nests made by previous territorial males. In this case, adoption and not infanticide is the behavior that yellow-headed blackbirds choose as a tool to actually increase eventual fitness (Gori et al . 1996).

Female infanticide in the house sparrow

Due to gamete dimorphism, sperm is cheaper to produce than eggs. Males can, thus, copulate with many more females and father more children than females can produce. Females, however, will devote more resources into the care for the young to compensate for the fewer number (Queller 1997). This allows for males to be more mobile. This, and the fact that because of the internal fertilization of eggs males can never be sure about their expected paternity in a brood, usually leads to males being the sex typically faced with the decision to adopt or kill a brood. However, females are presented with this dilemma too. In the house sparrow ( Passer domesticus ), females have to compete with each other for limited nesting space (Veiga 1990). This competition leads to the selection of behaviors that will increase the chances of a female taking over a nest and her raising her offspring up to fledge. Many times when a new female takes over a previously used nesting site, the other females’ young are still there. This new female now has to decide whether she should raise these offspring or if she should kill them. As expected, infanticide is not rare. In one study, female house sparrows committed infanticide over 20% of the time when females replaced other females (Veiga 2004). Moreover, because this nest is visited by the male that was helping to raise the other young, the female will kill off the other young in order to focus more of the male’s time and resources on the caring of her own young. She will mate with this male and lay a clutch of eggs where he expects high paternity.

Female infanticide can also occur without a female’s taking over a used nest site. In house sparrows, because the females are mated with a polygynous male, they are more likely to kill their rival’s offspring in order to get more of the male’s energy and time devoted to her and her offspring. When a polygynous male had other nests full of fledglings that needed care, female behavior that would give more, needed attention to her own offspring would be favored. Nearly 90% of these females committed infanticide (Veiga 2004).

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
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