Reproductive success and foraging ecology of the rusty blackbird on the Copper River Delta, Alaska Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/xg94hs15b

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • The Rusty Blackbird (Euphagus carolinus) has suffered significant population declines across its entire geographic range and the mechanisms associated with this decline are poorly understood. Although much of the Rusty Blackbird breeding habitat in Alaska has remained relatively unaltered by anthropogenic activities, this species continues to decline by an estimated 5% annually. As part of a collaborative effort to obtain data on the reproductive ecology, breeding success, and habitat requirements of this species throughout their range, a total of 42 nests were found and monitored for two consecutive breeding seasons (2009 – 2010) on the Copper River Delta in south-central Alaska. Nests were monitored every 2-4 days to calculate nest success, survival rates, clutch initiation date, clutch size, egg viability, and fledging rates. In 2010, chick provisioning rates, chick diet, and aquatic invertebrate availability in Rusty Blackbird foraging habitats were also investigated. Mean clutch size ranged from 5 to 7 eggs both years (2009 = 5.41 ± 0.15, 2010 = 5.67 ± 0.13). Daily nest survival rate averaged over both seasons was high, at 0.9913 ± 0.0043 (95% CI 0.9772-0.9967) and most eggs were viable (N = 31 nests), with 0.8922 ± 0.0275 of eggs over both seasons hatching. Approximately 85% of clutches were initiated within a two week period for both years of the study. Clutch-initiation date (CID) was significantly different between years (p-value < 0.0001), with mean CID of 10 May (x̅ = 10.476 ± 0.95) in 2010 and May 18 (x̅ = 18.421 ± 1.13) in 2009. The mean provisioning rate was 0.84 (± 0.06; 95% CI: 0.72 to 0.95) invertebrate food items per chick per hour. Large odonate nymphs, specifically dragonflies, made up the bulk (97.2%) of the observed food items provisioned to chicks. Weekly pond sampling revealed four taxonomic groups of invertebrates that were of the size observed provisioned to chicks (Coleoptera, Hirudinea, Zygoptera, Anisoptera) and Anisoptera were among the rarest collected (16.2%) of this size. Although the least common large invertebrate collected, Anisoptera nymphs were present in all weekly samples. The week with the most abundant Anisoptera collection coincided with the week of peak hatching during 2010 of the study. Thus, availability of dragonfly nymphs appear to be important to Rusty Blackbird reproductive success on the Copper River Delta and may have contributed to the high nest success observed in this study.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Keyword
Subject
Rights Statement
Peer Reviewed
Language
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2013-10-25T23:14:08Z (GMT) No. of bitstreams: 1 LoomisDavidM2014.pdf: 1081086 bytes, checksum: 0e2059f8a40789f5ab6ef29fd48af603 (MD5)
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2013-10-24T17:39:13Z (GMT) No. of bitstreams: 1 LoomisDavidM2014.pdf: 1081086 bytes, checksum: 0e2059f8a40789f5ab6ef29fd48af603 (MD5)
  • description.provenance : Made available in DSpace on 2013-10-25T23:14:08Z (GMT). No. of bitstreams: 1 LoomisDavidM2014.pdf: 1081086 bytes, checksum: 0e2059f8a40789f5ab6ef29fd48af603 (MD5) Previous issue date: 2013-05-31
  • description.provenance : Submitted by David Loomis (loomisd@onid.orst.edu) on 2013-10-24T02:20:30Z No. of bitstreams: 1 LoomisDavidM2014.pdf: 1081086 bytes, checksum: 0e2059f8a40789f5ab6ef29fd48af603 (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items