Genesis Award - 2000
The Genesis Award honors the best undergraduate poster at the annual meeting (see below).
“Geographic Variation in the Timing of Male Desertion in the Magnificent Frigatebird”, by Verónica Solares* and José Luis Osorno, Universidad Nacional Autónoma de México
Are males more likely to look after their chicks when food is scare? This seems to be the case at least with the magnificent frigatebird (Fregata magnificens). Males of this large sea bird always desert their single chick early in the season, leaving the female to raise alone the offspring for at least 14 months. This means that females invest in chicks for longer than males do. Males may get away with desertion because usually females can readily find sufficient food to rear the chick. Now, food availability is known to vary from year to year and may influence male desertion. This is because, when food availability is reduced, the females effort to get some food for their offspring and may be insufficient. Thus, under food scarcity, males should remain at the nest for longer than in localities or years of plenty. We checked whether relative food availability (RFA) is associated with variation in the patterns of parental care and timing of male desertion, by comparing parental care and chick growth in two colonies settled in different islands. The first is on the Pacific Ocean (Isla Isabel), where we worked for two years, 1994 (low RFA) and 1998 (intermediate RFA). The second, on the Atlantic-Caribbean, is Isla Contoy, where we worked in 1998 (high RFA). We found that at Contoy males fed the chicks less often, or desert earlier than those from Isla Isabel in both years but their chicks still grew faster and fledged earlier. This seemed to confirm our guess that whenever food supplies are sufficient to permit that one parent rises the chick alone, males can and do desert the nest, as happened at Contoy. Males at Isla Isabel could ill-afford to leave the whole package to their partners, since females themselves faced food scarcity and might have been forced to abandon their chicks if deprived of male support too early. Also, females at Contoy provided more food to their chicks than females at Isla Isabel in either year, further supporting the idea that it was easier for them to find food for their chicks. So, although ready to flee their duties, male frigatebirds facing a shortage in food supply do increase their parental investment by delaying their desertion, thus promoting offspring survival.
I started working with frigatebirds when I went as a volunteer to an island called Isla
Isabel in the Mexican Pacific. I collaborated in a project involving sexual selection of
frigatebirds under the supervision of Dr. José Luis Osorno at the Laboratory of Animal
Behavior at the National University of Mexico (UNAM). Since I realized how attractive are
those seabirds I decided to continue my academic formation in this area. In those days Dr.
Osorno was invited to work in other island called Isla Contoy in the Mexican Atlantic-
Caribbean. Dr. Osorno and I designed a project of parental care in frigatebirds with the
populations of both islands. In this great islands we can find a high number of species of
seabirds as boobies, pelicans, gulls, herons, tropic birds, sooty terns, cormorans, elegant
terns, royal terns, sandpipers, and so on. The work in both islands was very heavy
because the volunteers and I worked all the day and during some nights in the week
ringing and weighting chicks. Besides the mosquitoes were over us all the night. Instead of
all these inconveniences my experience in the field was very exciting because I could work
during those months in my own project and I knew a lot of people working on different
projects. This kind of islands represent a natural system where you can carry up many
topics of animal behavior research, that is why I am working there.