Technical Report

Middle Rio Grande Yellow-billed Cuckoo Study Results – 2023 Isleta Pueblo to Elephant Butte Reservoir, New Mexico Upper Colorado Basin Region; Technical Report No. ENV-2024-020

URL: https://webapps.usgs.gov/mrgescp/documents/2023-Middle-Rio-Grande-Yellow-billed-Cuckoo-Study-Results.pdf

Date: 2024/08/01

Author(s): Siegal R., Moore S.D.

Publication: Prepared by Bureau of Reclamation, Technical Service Center, Denver, Colorado.

Abstract:

During the summer of 2023, Bureau of Reclamation personnel conducted presence/absence surveys for the federally threatened Yellow-billed Cuckoo (Coccyzus americanus occidentalis (YBCU) within the Middle Rio Grande (MRG) riparian corridor between the Isleta Pueblo and Elephant Butte Reservoir, New Mexico. In accordance with established protocols, surveys were conducted during the YBCU breeding season (June 15 to August 15) to determine the distribution and abundance of YBCUs throughout this stretch of the MRG. During the 2023 breeding season, 452 YBCU detections were recorded within the MRG study area. From these detections, 114 territories were delineated; two were confirmed by locating nests, 60 were possible breeding pairs, and 52 were probable breeding pairs, as defined in Halterman et al. (2016). As in previous years, the San Marcial Reach contained the largest breeding population of YBCUs within the MRG study area, with 322 detections and an estimated 78 breeding territories. Forty-six of these territories were in the exposed pool of Elephant Butte Reservoir. The Bosque del Apache Reach produced the second highest number of territories —28 from 98 detections — 52 more detections than 2022. The Belen Reach produced 1 territory from 10 detections and the Tiffany Reach included 1 territory from 8 detections. Other river reaches were either not surveyed or surveys were reduced in 2023 due to lack of personnel. The San Acacia and Sevilleta reaches were not surveyed in 2023. Only two sites were surveyed in the Escondida Reach in 2023, just north of the Bosque del Apache. Within these 2 sites, 14 detections were recorded which comprised 6 territories.