San Diego County cactus wren survey finds broadly steady counts, with differences among clusters

What you need to know

• The 372 consistently surveyed plots had 35% occupancy in 2025, compared with 34% in 2024 and 35% in 2020 and 2021. Occupancy was lower in 2022 and 2023, so the latest figure sits within a variable series rather than showing a steady rise. 12
• Those same plots held 107 recorded territories in 2025, close to 106 in 2024 and below the series peak of 113 in 2021. These are observed territory counts, not an estimate of the total county population. 12
• The report recorded at least 83% of territories as occupied by pairs and noted 100 fledglings. Territory totals rose in San Pasqual, increased slightly in Lake Jennings, fell slightly in Sweetwater/Encanto and did not change in Otay. 1
• Habitat associations differed among genetic clusters. For example, the report identified selection for plots dominated by California buckwheat in Otay and broom baccharis in Lake Jennings. 1
• More than half of surveyed plots had over 5% non-native annual cover. Wrens were more often found in plots with less of that cover, although the survey does not establish that this pattern was caused by a management action. 13

Why this matters

Coastal cactus wrens are a conservation-priority bird associated with cactus scrub and coastal sage scrub, while habitat loss and fragmentation are identified as conservation concerns. Repeated measures of occupancy, territories and habitat condition can inform monitoring on conserved lands, but these results alone do not show that habitat or population status has improved. 34

What happens next

The monitoring programme is designed to track occupancy, territories, breeding status and habitat condition. The report does not specify a next survey date or banding plan; it notes that the small number of banded birds makes movement between genetic clusters difficult to assess. 13

What we know

• The 2025 survey covered 498 plots across four genetic clusters in San Diego County. 1
• Wrens were detected in 220 plots, with 184 territories recorded across all survey plots. 1
• The monitoring programme measures occupancy, territories, breeding status and habitat condition on conserved lands. 3

What we don't know

• The report does not explain what caused territory counts to change differently among the four genetic clusters. 1
• It is unclear how plot detections and observed territories relate to the total population size. 1
• The survey detected no movement by banded wrens between genetic clusters, but only three banded birds were observed. The available evidence therefore cannot establish whether movement occurred. 1
• The sources do not establish that the broadly steady counts represent a wider population recovery or that any management intervention caused the results. 123

Read the reporting

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