Holding Down the Fort: Hummingbird Territory Mapping Pre- and Post-Pandemic

Henry Avelar, Shane Stoyko, Lauren Powell, Jamie Abanes, Katya Contreras, Alexis Samuel, Ernest Wallace, and Dr. Allison Alvarado


Throughout the Western US, it has been documented that the Anna’s hummingbird (Calypte anna) has been expanding its range. However, in southern California where the Anna’s hummingbird has long occurred, our observations indicate that this species may be experiencing a local decline.  We hypothesize that the highly aggressive nature of a relatively new arrival to the southern California mainland, i.e. the Allen’s hummingbird (Selasphorus sasin), is pushing out and restricting the Anna’s hummingbird to marginal habitat. We investigate temporal variation in the proportion of territories occupied by Anna’s vs. Allen’s hummingbirds on and around campus. Before the pandemic, we collected data on spatial variation (and likely ecological segregation) of these hummingbird species. Our goal is to determine whether patterns from several years ago have changed over time. Formerly, we hypothesized that Anna’s will likely be replaced by Allen’s hummingbird territories in the natural areas surrounding campus, as the Allen’s expand outside their foothold in the campus garden areas. We currently test this hypothesis, with the null being no change in relative abundance of Allen’s vs. Allen’s since pre-pandemic levels. This research has implications for the conservation of a potentially vulnerable bird population that is being adversely affected by changes in the biotic community.

One Comment

  1. Great presentation! Interesting to see the expansion of the range of the Anna’s hummingbird and how drought appears to affect the abundance of both species. Since Anna’s hummingbirds forage mostly on two native plants on campus, have you observed if they use the same or other species of plants in considerable amounts at Camarillo Park?

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