Wood Warbler Population and Habitat Trends.
Chris Wood, from COA
cwood022@gmail.com
Chris has been a Connecticut birder for over 45 years and has participated in the Woodbury/Roxbury Summer Bird Count since its inception. He is currently Vice-President of COA and has been active with many bird and conservation organizations and research projects in Connecticut. He has served on the Avian Records Committee of Connecticut and Chaired the Breeding Bird Atlas Steering Committee from 1981 – 1985.
This presentation begins at 4 hours 11 minutes on the video recording: COA's Birds and the Environment Science Conference - Online - YouTube
This is a working draft, under construction. More of these slides will be added, from the original slide deck PDF file...
Chris Wood presented the results of his analysis of wood warbler abundance based on 35 years of data from the Woodbury/Roxbury Summer Bird Count. The analysis looked at three warbler species in each of five different habitat settings and plotted trend lines indicating the status of each species over the study period.
The resulting graphics demonstrate trends explainable by comparison to recognized trends in habitat loss, degradation, and recovery throughout the study area (15 mile diameter circle) in central western Connecticut.
Observations
• Succession and edge habitat species (Blue-winged Warbler, Chestnut-sided Warbler, and Prairie Warbler) have declined in reported SBC observations, consistent with the loss of such habitat as old field and forest edges either mature into second growth forest or are cleared for development or agriculture.
• SBC reports of evergreen forest species (Blackburnian Warbler, Pine Warbler, and Black-throated Green Warbler) within the study area show increasing or at least stable numbers. Pine groves especially are early colonizers of cleared forest areas from logging and abandoned farm lands.
• Also showing increases in SBC reported numbers are species favoring mixed forest with dense understory (Black-throated Blue Warbler, Hooded Warbler, and Worm-eating Warbler). Selective forestry is likely opening up the forest floor to more sunlight, allowing Mountain Laurel and similar species to thrive in certain areas.
• On the other hand, species dependent on large blocks of deciduous and mixed woods (Black-and-white Warbler, Ovenbird, and American Redstart) show mostly declining numbers counted except the AMRE, which appears to be more accepting of forest edges than the other two species. Rapid loss of unfragmented forest land – forest blocks of 500 or more acres – likely contributes to the decline of some species.
• Wetlands preferring species (Common Yellowthroat, Yellow Warbler, and Louisiana Waterthrush) also show a bit if diversion in the population trends. COYE and YEWA are both seen as declining in the study area, while LOWA counts are stable or even increasing. The latter has a more specialized habitat preference – woodland streams – but identifying any correlation will require further work. The loss and degradation of wetlands habitats has been well documented.
The report points out that other factors may apply to the observed trends: species’ range-wide trends; condition of winter habitats; climate change; and observer effort.
Overall conclusions from the analysis were:
• Wood Warbler populations provide useful insight into larger ecological and environmental trends.
• Avocational research is an important tool for identifying and documenting those trends.
• Finding and counting Wood Warblers is one of the highlights of anyone’s birding year.
This analysis was published as “Wood Warbler Population and Habitat Trends” in The Connecticut Warbler Vol. 40 #1 (January 2020)
Other recent Connecticut Warbler articles by Chris Wood:
“Hermit Thrushes and the Breeding Bird Atlas in Connecticut”, Vol. 41 #1
“Since the Breeding Bird Atlas – Observations on Some Positive Trends”, Vol 38 #1
Wood also recently presented a COA Workshop on finding and identifying wood warblers in Connecticut.
The Connecticut Warbler articles and the workshop can be viewed by COA members on the COA website https://www.ctbirding.org/
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