Design Reflections – Red-winged black bird

Creating a field research experiment and implementing a sampling strategy has been rather challenging. The Red-winged blackbird is a migratory song bird that is suggested to appear in March to breed (Semeniuk, 2020). Yet, from my observation this birds appeared much earlier than suggested this year. Thus, I wanted to test to see if the Red-winged blackbird migration was related to elevating temperature. I started with a basic model for sampling using a transect line and points along the transect and surveyed (counted) for 15 minutes at each site. My original location for counts was McConnell Lake at the far north-western side where their is a marsh area. But, I had witnessed no Red-winged blackbirds. By chance, I ended up at the Dufferin Wetlands Park and low and behold there were numerous blackbirds. I recognized that I needed to expand my sites to include this location and also felt like adding in Gamble Pond where I had conducted ecology studies before would be valuable. During a count at Gamble Pond, a fellow birder stopped to inquire what I was up to and referred me to another location which was Pineview Valley Park. Before adding sites however, I had recognized that sampling using a transect line posed problematic: my counts were way higher than what I estimated for blackbirds in the area (on several occasions I witnessed birds flying from one area into the next); and, 15 minutes was way to long. Thus, following reading the study on avian species densities along an urban gradient (Blair, 1996), I felt like variable circular plot method may be a better strategy. I felt like things were going smoothly but was concerned that my data collection was coming together rather haphazardly. Yet, it seemed to be going well. When I posted my ongoing field observations Robyn posed an incredibly good question to which was something along the lines of: Were you able to collect data before, during, and after the warm period? I had unfortunately went away and missed a prime sampling window when temperatures increased and then dropped again. Sadly, I know I have to modify my approach again. What I have since witnessed however, is that the male Red-winged black birds that while they tended to be most active on warm days (calling and flying around), it wasn’t until females arrived that their aggression started. At all the locations (excluding McConnell where there were no blackbirds at all) the males had appeared first and there were higher numbers of males than females. I feel like at this point it would be best for me to rework my study and look just at behaviour of the Red-winged black bird as aggression is an important aspect of sexual reproduction. One prominent study on blackbird aggression suggested that female-female aggression may relate to guard the non-shareable portion of the male’s parental investment (Yasukawa & Searcy, 1982). Yasukawa and Searcy (1985) also suggest that the Red-winged blackbird is one of the most polygynous bird species with up to 15 nesting females found within the territory of one male. This will improve my research as my hypothesis will be easier to test and I expect less confounding variables.

References

Semeniuk, T. (2020, June 20). Birder’s guide to McGowan Park. Kamloops Naturalist Club. Retrieved from https://kamloopsnaturalistclub.com/birders-guide-to-mcgowan-park/#:~:text=In%20March%2C%20male%20Red%2Dwinged,and%20trees%20surrounding%20the%20pond.

Yasukawa, K., & Searcy, W. A. (1982, August). Aggression in female Red-winged blackbirds: A strategy to ensure male parental investment. Behavioural Ecology and Sociobiology, 11, 13-17. DOI: https://doi.org/10.1007/BF00297660.

Yasukawa, K. and W. A. Searcy (2020). Red-winged Blackbird (Agelaius phoeniceus), version 1.0. In P. G. Rodewald (Ed.) Birds of the World. Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.rewbla.01.