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Parenting Reaction Norms in
Sparrows |
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House sparrows fit the stereotypical
profile of a monogamous bird—both male and female contribute extensively to
providing for and protecting the offspring. We have been and are continuing
to study biparental care in sparrows, starting in 1997 with Ph.D. student Meg
Hatch’s work on age-related patterns of parental care (Hatch and Westneat 2007,
2008),
Tria Kinnard’s work on sources of variance in nestling quality (Kinnard and
Westneat 2009), and
presently with Dan Wetzel’s study of individual differences in care. Our
current approach is to treat parenting as a behavioral reaction norm. A
behavioral reaction norm defines behavior as a function of individual
identity and the environmental context in which the individual performs the
behavior. It is an explicitly statistical description of variation in
behavior. Dan, Amanda Ensminger (also a Ph.D. student in my lab), Meg and I
reanalyzed Meg’s data on provisioning rate by male and female sparrows using
this approach. We found four major results: 1. Provisioning
rate shows both plasticity and personality, with plasticity having an effect
on the measure of personality, 2.
Sparrows show apparent complex personality,
responding to interaction between environmental variables, 3.
The sexes differ in plasticity in
multiple environmental dimensions, but they do not differ in personality, and 4. There
is individual variation in plasticity with respect to nestling age and
partner behavior, and this is correlated with personality. The paper on this recently has
been published in The American
Naturalist! Dan is collecting additional data and conducting experiments
on nestling demand, and measuring parental skills at acquiring food. I have a
grant proposal in review seeks to understand personality and plasticity in
delivery (food provided per unit of time per trip). A central goal will be to
understand individual and environmental effects on variances as well as means
of delivery. This work will take 4-5 years to complete—Dan finishes in a
year, so this could be a topic suitable for a new student! |
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