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Contributed Talk

Session: : Climate Change: Ranges And Phenology 1

COS 230-2 - Identifying multitrophic phenology shifts using remote sensing: a case study of insects and aerial insectivores in the Great Lakes

Thursday, August 10, 2023
8:15 AM – 8:30 AM PDT
Location: B118
Abstract: Shifts in the timing of seasonal events in response to global change are commonly documented across taxa. Differences in organisms’ response to warming can results in trophic mismatches, particularly when the seasonal constraints or cues differ across taxa. Here, we explore phenological shifts across trophic levels in an insect-aerial insectivore system using weather surveillance radar and satellite data. We use the US weather surveillance radar network to collect data on animal activity in the Great Lakes region over the past decade. We quantify seasonal day-flying insect activity and communal swallow and martin roosts, and combine this with NDVI and local air temperature to identify similarities in their response to global change.

We find phenological advances across trophic levels, but strong differences in the magnitude of this shift. For aerial insectivores, bird roosts advanced in their 75 and 90% passage date by 3.1 and 4.1 days per decade respectively. Late summer insect activity also advanced, but more quickly: by 9.1 and 7.5 days per decade (date of 75% annual abundance and date of 90% annual abundance respectively.) Vegetation green-up advanced most quickly. Both insect and insectivore phenology shifts were best predicted by local air temperature warming.

Our results indicate that insects and their aerial predators may be experiencing a trophic mismatch, with insect flight activity advancing more rapidly than the phenological shift in swallow and martin roosts. The mismatch between insectivore and insect phenology was greater than the mismatch between vegetation and insect phenology. We also observed an extension in the duration of the insect flight season in response to warming. Insect populations may be better able to track environmental change as a result of their life cycle and shorter generation times. In contrast, bird roosting behavior is likely more constrained due to the demands to complete breeding prior to roosting. These different limitations on life history likely result in distinct flight phenology patterns in response to warming.

Our research shows disparate shifts in phenology across trophic levels, suggesting that species interactions may be disrupted under global change conditions.