Nest material selection in European starlings: assessing the influence of anthropogenic materials and feathers on nestling success

Many bird species incorporate natural materials (e.g. feathers) and anthropogenic material (e.g. plastic) into their nests. Studies suggest that the colour of feathers within a nest may be strategically chosen by birds for their anti-bacterial effects. Hypotheses as to why birds incorporate anthropogenic material into nests include those of material availability, structural support, ornamentation, signaling, and anti-parasitism. My first objective was to determine whether white or pigmented feathers were more abundant in European starling (Sturnus vulgaris) nests and whether each feather colour was correlated with hatching success, brood condition, and/or fledging success. My second objective was to categorize the types of anthropogenic material commonly found in European starling nests and to determine if these different types affect the reproductive variables. I monitored hatching success, brood condition, and fledging success in 33 nests over two broods in 2025, within a nestbox-breeding starling population on the campus of Saint Mary’s University in Halifax, Nova Scotia. I collected nests after fledging for dissection. Starlings preferred pigmented over white feathers, but neither had an effect on reproductive success. Of the anthropogenic materials, clear plastic was the most commonly included material followed by paper, coloured plastic, foil, string/twine, ribbons, fabric, popsicle sticks, foam, cigarettes, and gum. A negative correlation existed between day 11 brood condition and amount (mass) of clear plastic, suggesting that plastic negatively impacted nestling health. Hatching success was positively correlated with the mass of coloured plastic, suggesting it attracted a high-quality mate or encouraged incubation. My findings indicate that the nest material selected by European starlings may be influenced by material availability and ornamentation strategies. The material availability hypothesis is supported by the abundance of pigmented feathers and clear plastic in nests reflecting their omnipresence in the environment while coloured plastic attracting a high-quality mate supports the ornamentation hypothesis.