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1. Bird abundance and its environmental controls in major ecosystems across the U.S.

   Qian, Anita; Xu, Xiaofeng (August 2024, ESA)

   Qian, Anita; Xu, Xiaofeng (Ed.)

   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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2. The effects of changing vegetative composition on the abundance, species diversity and activity of birds at the Jornada Basin LTER site, 1997

   https://doi.org/10.6073/pasta/9ce9a7139153fa22636bdfef63c4cdb8  

   Bogner, Heidi; Huenneke, Laura F (January 2021, Environmental Data Initiative)

   This data package contains bird abundance data collected in plots that have had various plant functional groups or species experimentally removed at the Jornada Basin LTER site in southern New Mexico, USA. This data was collected in an effort to distinguish the differential effects of plant community biomass, plant community functional groups, and biodiversity within functional groups on plant community function, including effects on animals. To make these distinctions, treatments were established by the selective removal of plant species or functional groups within experimental plots. There are eight treatments: control (C, no removals); four functional group removal treatments (PG, perennial grass removed; S, shrubs removed; SSh, subshrubs removed; Succ, succulents removed), and three species richness manipulation treatments. Richness manipulations included a simplified treatment (Simp), where only the single most abundant species of each growth form is preserved and all other species in the growth form are removed, a reduced‐Larrea treatment (rL), where the Larrea is assumed to be the dominant and is removed while minority components remain, and a reduced-Prosopsis treatment (rP), where Prosopis rather than Larrea is removed as the shrub dominant. Following treatments, bird abundance and habitat preference data was collected in 1997. This data set consists of plot number, treatment type, and time of bird presence by taxa and by habitat and behavior. This study is complete. 

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3. Active restoration accelerates recovery of tropical forest bird assemblages over two decades

   https://doi.org/10.1016/j.biocon.2024.110593  

   Joyce, Francis H; Rosales, Juan Abel; Holl, Karen D; Zahawi, Rakan A; Bui, An; Reid, J Leighton (May 2024, Biological Conservation)

   Choosing effective methods to restore habitat for the diverse faunal assemblages of tropical forests is hampered by lack of long-term data comparing multiple restoration treatments. We conducted area counts of bird assemblages over 12 years (~5–17 years since restoration) in a blocked experiment with two active planted treatments (tree plantations and applied nucleation) and a passive restoration treatment (natural regeneration) replicated at 11 sites in Costa Rica. We also surveyed six pastures and five remnant forest sites to assess recovery of avian species richness, composition, forest specialists, and range-restricted species in restoration plots relative to degraded and reference systems. Restoration treatments showed increased resemblance of avian assemblages to remnant forest over time. Applied nucleation proved equally effective as plantation, despite a reduced planted area, whereas natural regeneration recovered more slowly. Assemblage-level trends in avian species richness and compositional similarity to reference forest are underpinned by reductions in use by pasture birds and by gradual increases in richness of forest-affiliated species. Because forest-affiliated species tend to have narrower distributions than the open-country species they replace, forest restoration can reduce biotic homogenization at the local scale. Restoration practitioners should consider applied nucleation as an alternative to standard plantations if seeking rapid recovery of bird assemblages. However, the ecological return on investment from natural regeneration increases over a couple of decades. Managers should monitor trends in forest-affiliated and rangerestricted species to track the recovery of the full avian assemblages, since coarse metrics like species richness and overall compositional similarity may plateau relatively quickly 

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4. Meta-analysis shows that overabundant deer (Cervidae) populations consistently decrease average population abundance and species richness of forest birds

   https://doi.org/10.1093/ornithapp/duab040  

   Crystal-Ornelas, Robert; Brown, Jeffrey A; Valentin, Rafael E; Beardsley, Caroline; Lockwood, Julie L (September 2021, Ornithological Applications)

   Abstract Local-scale studies have shown that an overabundance of Cervidae species (deer, elk, moose) impacts forest bird communities. Through meta-analysis, we provide a generalized estimate of the overall direction and magnitude of the indirect effects overabundant cervids have on avian species. We conducted 2 distinct meta-analyses that synthesized data on 130 bird species collected from 17 publications. These analyses compared bird species’ population abundance and/or species richness at sites with overabundant cervids to sites with lower cervid abundance or without cervids. We evaluated whether the impacts of overabundant cervids are generally in the same direction (positive, negative) across avian species and locations and if effects vary in magnitude according to avian nesting location and foraging habitat. We found that where cervids were overabundant, there was a significant decrease in mean bird population abundance and species richness. Species that nest in trees, shrubs, and on the ground showed the largest decreases in abundance, as did species whose primary habitat is forest and open woodland and species that are primarily insectivores or omnivores. We did not find significant decreases in abundance for avian species that nest in cavities, whose primary habitat is grassland or scrub, nor for species that mainly eat seeds. Our results indicate that overabundant cervids, likely through their direct effects on vegetation and indirect effects on insects and forest birds, negatively impact individual bird populations and decrease overall avian species richness. 

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5. Invasive swamp eels reduce aquatic animal diversity and disproportionately reduce prey for nesting wading birds

   https://doi.org/10.1038/s41598-025-02887-y  

   Pintar, Matthew R; Dorn, Nathan J (December 2025, Scientific Reports)

   Ecosystem restoration often aims to create environmental conditions that support communities of native organisms resembling those prior to alteration by humans. One focus of the multi-decade multi-billion-dollar Florida Everglades restoration effort is to recreate hydrologic conditions in Everglades National Park and associated pulses of aquatic animal prey to support the large colonies of seasonally nesting wading birds that are iconic predators in the ecosystem. Recent studies indicate that invasion of predatory Asian Swamp Eels (Monopterus albus/javanensis) has disrupted the hydrology-mediated production of crayfish and some small fishes in the drainage of first invasion (circa 2012). Here we used a complete community dataset of fish and decapods to report changes to the aquatic community diversity, composition, and biomass of prey produced for wading birds. After the establishment of swamp eels in Taylor Slough (Everglades National Park) average fish and decapod richness declined by 25% and communities shifted to a new state dominated by grass shrimp and a few species of small fishes. Swamp eels differentially reduced the production of primary wading bird resources; while there has been a 68% decline in total small fish and decapod biomass, the biomass of the most important prey species for nesting wading birds declined 80%. If similar impacts follow the spread of swamp eels into other major drainages of the Everglades, the invasion may precipitate an ecosystem collapse—fundamentally simplifying and restructuring the aquatic communities of this vast wetland ecosystem and limiting the trophic support for wading bird breeding aggregations that are important indicators for ecological restoration. 

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