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Abstract Manipulation experiments are a cornerstone of ecological research, but can be logistically challenging to execute—particularly when they are intended to isolate the ecological role of large, vagile species, like birds. Despite indirect evidence that birds are influential in many ecosystems, large‐scale, multi‐year bird manipulation experiments are rare. When these studies are conducted, they are typically realized with caged or netted exclosures, an approach that can be expensive, risky for wildlife, and difficult to maintain. In cases where caged exclosures are not appropriate, alternate approaches are needed to allow rigorous empirical studies on the ecological role of birds. Here, we present and validate a method for experimentally increasing the abundance and richness of birds at the scale of entire aquatic ecosystems. Unlike bird exclusion, this approach is experimentally tractable, appealing to land managers, and possible to deploy over large spatial scales. We tested the efficacy of our approach for increasing bird abundance and species richness at 16 central California ponds. Based on bird visitation data obtained by summer camera trapping, our approach significantly increased bird species richness and abundance at manipulated ponds compared to control ponds. Attractant treatments mitigated the negative effects of a major drought on bird species richness and generated a near doubling of bird abundance in the presence of attractants. Treatments had no effect on most mammal species, with the exception of ground squirrels, which increased in abundance in the presence of attractants. These results suggest that attractants are effective in increasing bird abundance and richness. We encourage researchers to consider this approach for experimentally isolating the ecological role of birds in aquatic and open terrestrial ecosystems, especially in cases where cost or logistical constraints preclude the use of caged or netted exclosures.
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Bird abundance and its environmental controls in major ecosystems across the U.S.
Birds play a crucial role in maintaining the balance and health of ecosystems worldwide, with their significance extending from ecological functions to cultural symbolism. Ecologically, birds contribute to pest control by preying on insects, regulating populations, and mitigating agricultural damage. They also aid in seed dispersal and pollination, facilitating vegetation growth and plant reproduction. Furthermore, birds serve as environmental indicators, reflecting broader ecological shifts. Recently, the National Ecological Observation Network (NEON) has undertaken the task of monitoring bird populations across various U.S. ecosystems. The project aims to decipher bird abundance patterns during peak growing seasons, synthesizing data on variables such as bird counts, beetle populations, latitude, longitude, tree dimensions, and vegetation productivity during 2017-2022 sourced from NEON databases. The findings reveal that bird counts decrease from low to high latitudes, with both beetles and vegetation productivity positively influencing bird abundance, while tree breast height diameter shows weak correlation. Strong inter-annual variations in bird counts were observed nationwide. Both correlation analysis and structural equation modeling underscore vegetation's pivotal role in bird abundance. In essence, the developed bird count data system offers valuable insights into bird and ecosystem health, aiding communities in understanding and preserving these vital ecosystems.
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- Award ID(s):
- 2145130
- PAR ID:
- 10565812
- Editor(s):
- Qian, Anita; Xu, Xiaofeng
- Publisher / Repository:
- ESA
- Date Published:
- Format(s):
- Medium: X
- Location:
- Long Beach, CA
- Sponsoring Org:
- National Science Foundation
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