Sparrow preferences for winter cover crops in California's central coast

Authors: Brennan, Eric

Submitted to: Frontiers in Sustainable Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2020
Publication Date: 11/17/2020
Citation: Brennan, E.B. 2020. Sparrow preferences for winter cover crops in California's central coast. Frontiers in Sustainable Food Systems. 4. Article 567579. https://doi.org/10.3389/fsufs.2020.567579.
DOI: https://doi.org/10.3389/fsufs.2020.567579

Interpretive Summary: There is a need for information on agricultural practices that enhance biodiversity of birds and other beneficial species in intensive agricultural systems. A study was conducted in the winter cover cropping period in Salinas, CA to determine how cover crops would influence birds. Cover crops included cereals, legume-cereal mixtures, and mustards. Three sparrows were observed in the cover crops including the White-crowned sparrow (Zonotrichia leucophyrs), the Savannah sparrow (Passerculus sandwichensis), and the Song sparrow (Melospiza melodia). Sparrows preferred the habitat provided by the mustard cover crop more than that of other cover crops. The presence of leaf tissue in most bird droppings collected under the cover crops indicates that they were produced by Z. leucophyrs. This study shows that winter cover crops can provide a valuable winter habitat for birds.

Technical Abstract: Agriculture in many regions of the world has reduced bird habitat and abundance. Research that examines the impact of intensive agricultural management practices on biodiversity of birds and other beneficial species is needed. A study was conducted during two winter cover cropping periods from October to March in Salinas, CA to determine how cover crop variety and planting density influenced bird behavior, and the abundance and composition of bird droppings. Cover crops were rye (Secale cereale), oat (Avena sativa), a mixture of rye or oats and legumes (Vicia species and Pisum sativum), and a mustard mixture (Brassica juncea, Sinapsis alba). The study occurred on a conventional site from 2002 to 2003 (year 1) and on an organic site from 2006 to 2007 (year 2). Seeding rate was only evaluated during year 2. Zonotrichia leucophyrs was seen in the cover crops both years and two other sparrows (Passerculus sandwichensis, Melospiza melodia) were also seen in year 2. Bird droppings under cover crops were quantified and dissected to determine dietary preferences both years. Sparrow presence and movement between cover crops were recorded in year 2. Planting density had no effect on sparrows. Sparrows were most common in mustard, and flushed sparrows usually flew between mustard plots. Dropping number and weight m-2 were in order of mustard = legume-oat mix > oat > rye in year 1, and mustard > legume-rye mix =rye in year 2. Droppings in year 1 all included weed seed and usually included leaf and insect fragments, however, in year 2, leaf tissue dominated droppings from mustard and insect fragments dominated droppings in rye and legume-rye mix. The presence of leaf tissue in most droppings indicates that they were produced by Z. leucophyrs. Possible explanations for bird preference for mustard cover crops are discussed.