Sagehen Creek Field Station

05 May, 10 AM - 29 Jun, 05 PM

Elise Ferree Sagehen Creek Field Station Project Description for April-July 2003 I plan to study how Dark-eyed junco females allocate their energy during breeding based on the quality of their mate. The differential allocation hypothesis (DAH) proposes that a female will invest more in a nesting attempt if she has an attractive mate than if her mate is of lower quality (Burley 1986). This can be tested in species with sexually selected male traits, and we know that female juncos prefer males with the greatest number of white tail feathers (Hill et al 1999). To test the DAH I will alter white tail feathers of males and determine how their mates adjust their investment based on the manipulation. I am also interested in how a female may adjust the paternity of her young by mating with males of better quality than her social mate. This is another strategy she can use to better her lot when mated to a low-quality male. I will use my first field season to gather observational data and test the experimental methods. To get base line life-history data on the population, I will locate and monitor 30 nests and conduct nest watches during the incubation and nestling stages. Each adult will be captured (using mist nets and baited potter traps), banded (with aluminum and color bands), bled, measured, and weighed. Blood samples will be collected in capillary tubes (50-100uL) from the brachial vein in the wing. I will also band and collect blood from nestlings when they are 7-8 days old, before they fledge on day 12-13. Sampling blood from all individuals will allow me to later determine paternity of each brood. Ten nests will be used as experimentals this year in a pilot study for future field seasons. The males of these nests will undergo feather manipulations once they have paired with a female. Juncos have 6 pairs of tail feathers, with most being dark gray, but the outermost 2-3 feathers being white. Using methods applied to juncos in two other studies (Holberton et al 1989, Hill et al 1999), I will increase the number of white tail feathers in these 10 males. Briefly, a feather is cut about 1 cm from its base, hollowed out with a needle, and then a new feather is inserted and glued (super glue) into the remaining shaft. Because birds molt at the end of the breeding season the manipulation will be naturally undone. The DAH has been tested in 7 species to date, but additional tests are needed due to problems inherent in many of these studies. Furthermore, extra-pair paternity as an alternative strategy to differential allocation has not been examined. Finally, a broad basis of knowledge is available for juncos that provides much of the background necessary for me to test the DAH in this species.

Visit #1232 @Sagehen Creek Field Station

Approved

Under Project # 1035 | Research

Dark-eyed Juncos

graduate_student - University of California, Santa Cruz

Reservation Members(s)

Elise Ferree May 5 - Jun 29, 2003 (56 days)
Elise Ferree May 5 - Jun 29, 2003 (56 days)

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East Cabin (Lower Camp) 2 May 5 - Jun 29, 2003