Date of Submission
Environmental and Urban Studies
Project Advisor 1
It is well-known that many animal species can detect polarized light cues of water and water-like objects in the visible and ultraviolet range. However, studies investigating if birds can see polarized light in field-based settings are rare. Furthermore, no studies have yet been conducted to understand avian attractiveness to vertically polarized light, nor have studies considered other natural polarizers of light such as tree sap. I designed a choice-field experiment to investigate if birds can detect, and are attracted to vertically polarized light. First, I cut six pieces of clear vinyl into a foot by 54 inches. I painted each vinyl sheet with Black 3.0, advertised as the blackest paint in the world. Two treatments were wrapped around two trees similar in dbh (<40 dbh) and close in distance (<5 feet): one had shiny exposed, and the other matte, painted side, exposed. Suet feeders were hung directly below each treatment on both trees. Two remote cameras were placed on a fence post away from both tree (10 feet in fall; 6 feet in spring). The suet feeder height, camera distance, and the height of both vinyl stayed the same. These treatments were exposed to birds. A baseline study was conducted before installation of treatments to understand bird biases or preferences to one tree position over the other. I made conclusions about birds being able to see, and their attraction to, vertically polarized light by capturing and counting visitations from images, and comparing treatments’ bird visits over a designated period of time. My results revealed that birds are able to detect and are attracted to vertically polarized light, and use it to guide foraging behavior. Attraction to polarized light is dependent upon the location of the site, as well as the position (left or right tree), and certain species may play a role in these conclusions, though they do not overwhelm the data. The baseline study to treatment comparison reveals that any preferences to one position over the other were eliminated when treatments were added, and the polarized, shiny treatment had more of a signal than the matte treatment when each treatment were compared separately to the baseline. These results suggest a need to expand site-wise across various habitats to understand the effects of site location, to understand the effects of the positionality of treatments on different species of trees, and to understand how different species may have an effect on treatment visitation. Sap was imaged using a polarimeter to understand if natural Maple sap polarizes light compared to my polarized proxy for sap. My analyses reveal that natural Maple sap polarizes light, and this is strongest in the ultraviolet range. My treatments polarize a high degree of light in both the visible and ultraviolet range, making it an effective simulator of natural Maple sap. This exciting discovery gives insight on how birds may navigate a complex landscape according to polarized cues of that landscape (polarization of sap), and how they use these cues to facilitate their foraging behavior (eating sap).
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Kuczek, Aurora Belle, "Avian Attractiveness to Vertically Polarized Light" (2021). Senior Projects Spring 2021. 205.
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