Abstract
During the incubation period, most avian embryos arereliant on their parents for development. In parasiticspecies like the Brown-headed Cowbird (Molothrusater; hereafter “cowbird”), this developmental burden istransferred to the parents of the host species. Cowbirdsparasitize many host species, thus their embryos mustbe able to develop within a wide range of incubationstrategies utilized by their host parents. To investigatethe development of cowbird embryos, we examinedtwo aspects of the incubation stage: 1) the variabilityof cowbird embryonic heart rate within different hostspecies, and 2) how incubation behaviors by hosts dif-fered with parasitism. Embryonic heart rate was mea-sured using a non-invasive ballistocardiogram on eggsevery three days. Incubation behaviors were examinedusing iButton temperature loggers to record changes innest temperature. We found no significant effects ofhost species on cowbird embryonic heart rate; cowbirdheart rates were similar despite being incubated by dif-ferent host species. Host species incubation behaviorsdid not differ with parasitism status in three of the fourspecies we investigated. Only Indigo Buntings (Passe-rina cyanea) differed, with greater numbers of bouts offthe nest per day, as well as a lower percentage of timeof the day spent incubating when cowbird eggs werepresent. Cowbird embryos appear able to develop, re-gardless of the incubation behavior of their host parents,however some species may alter their incubation whenparasitized. In the 2020 field season we will conduct anexperiment to further understand how hosts may changetheir incubation behavior when parasitized.
| Original language | English (US) |
|---|---|
| Title of host publication | NAOC 2020, Abstract Book. |
| State | Published - 2020 |