On behalf of my coauthors, I am pleased to share that our new paper has just been published in Ecological Indicators: Transue, L. M., Van Parijs, S. M., Tennant, S. C., Linden, D. W., Briner, R., Koilpillai, H. A., & Davis, G. E. (2026). A standardized framework for quantifying species occurrence, applied to passive acoustic monitoring of baleen whales. Ecological Indicators, 188, Article 114943. https://doi.org/10.1016/j.ecolind.2026.114943 ABSTRACT: Environmental monitoring increasingly relies on non-invasive, presence-only data, like passive acoustic monitoring (PAM), yet the field lacks standardized frameworks to quantify changes in species' occurrence patterns. This study introduces a reproducible methodological framework to translate qualitative presence-absence time series data into comparable quantitative indices using recurrence (re-detection probability within a defined temporal window), a magnitude of change metric quantifying interannual variation, and persistence (consecutive presence duration). To validate these metrics, acoustic presence patterns of four endangered baleen whale species were analyzed using a decadal (2014–2023) PAM dataset from 112 sites across the U.S. East Coast. These metrics quantified diverging ecological realities: dietary generalist fin whales (Balaenoptera physalus) exhibited highly consistent patterns (97% recurrence, average magnitude of change <7%, average persistence up to 42.6 days) while dietary specialist North Atlantic right whales (Eubalaena glacialis) exhibited highly variable patterns (26%–96% recurrence, average magnitude of change

30%, average persistence <5 days). Furthermore, this framework captured the right whale's known decoupling from historical habitats associated with declining prey availability. Sei (Balaenoptera borealis) and blue whales (Balaenoptera musculus) exhibited seasonally discrete recurrence (93%) that aligned with their known seasonal foraging and migratory strategies. By characterizing these trends across species with varying foraging strategies, this framework demonstrates how multi-species monitoring can function as an ecological indicator of broader ecosystem and trophic trends. While demonstrated here using acoustics, this approach is applicable to any long-term presence-only data stream, bridging the gap between high-resolution monitoring and the requirements of quantitative ecological indicators.

Best, Lindsey Transue