1
|
Eichenwald AJ, Fefferman NH, Reed JM. Potential extinction cascades in a desert ecosystem: Linking food web interactions to community viability. Ecol Evol 2024; 14:e10930. [PMID: 38362165 PMCID: PMC10867880 DOI: 10.1002/ece3.10930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 11/27/2023] [Accepted: 12/05/2023] [Indexed: 02/17/2024] Open
Abstract
Desert communities are threatened with species loss due to climate change, and their resistance to such losses is unknown. We constructed a food web of the Mojave Desert terrestrial community (300 nodes, 4080 edges) to empirically examine the potential cascading effects of bird extinctions on this desert network, compared to losses of mammals and lizards. We focused on birds because they are already disappearing from the Mojave, and their relative thermal vulnerabilities are known. We quantified bottom-up secondary extinctions and evaluated the relative resistance of the community to losses of each vertebrate group. The impact of random bird species loss was relatively low compared to the consequences of mammal (causing the greatest number of cascading losses) or reptile loss, and birds were relatively less likely to be in trophic positions that could drive top-down effects in apparent competition and tri-tropic cascade motifs. An avian extinction cascade with year-long resident birds caused more secondary extinctions than the cascade involving all bird species for randomized ordered extinctions. Notably, we also found that relatively high interconnectivity among avian species has formed a subweb, enhancing network resistance to bird losses.
Collapse
Affiliation(s)
| | - Nina H. Fefferman
- Department of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxvilleTennesseeUSA
| | - J. Michael Reed
- Department of BiologyTufts UniversityMedfordMassachusettsUSA
| |
Collapse
|
2
|
Getman-Pickering ZL, Soltis GJ, Shamash S, Gruner DS, Weiss MR, Lill JT. Periodical cicadas disrupt trophic dynamics through community-level shifts in avian foraging. Science 2023; 382:320-324. [PMID: 37856588 DOI: 10.1126/science.adi7426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/25/2023] [Indexed: 10/21/2023]
Abstract
Once every 13 or 17 years within eastern North American deciduous forests, billions of periodical cicadas concurrently emerge from the soil and briefly satiate a diverse array of naive consumers, offering a rare opportunity to assess the cascading impacts of an ecosystem-wide resource pulse on a complex food web. We quantified the effects of the 2021 Brood X emergence and report that more than 80 bird species opportunistically switched their foraging to include cicadas, releasing herbivorous insects from predation and essentially doubling both caterpillar densities and accumulated herbivory levels on host oak trees. These short-lived but massive emergence events help us to understand how resource pulses can rewire interaction webs and disrupt energy flows in ecosystems, with potentially long-lasting effects.
Collapse
Affiliation(s)
- Zoe L Getman-Pickering
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA
| | - Grace J Soltis
- Department of Entomology, University of Maryland, College Park, MD 20742, USA
| | - Sarah Shamash
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA
| | - Daniel S Gruner
- Department of Entomology, University of Maryland, College Park, MD 20742, USA
| | - Martha R Weiss
- Department of Biology, Georgetown University, Washington, DC 20007, USA
| | - John T Lill
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA
| |
Collapse
|
3
|
Lepori F. Stream pollution causes aggregation of wintering insectivorous birds through increased aquatic emergence. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.926529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cross-boundary prey subsidies can propagate the effects of human impacts from streams to terrestrial ecosystems, but effects during winter are poorly known. Here I focused on this season and investigated the effects of pollution due to a sewage treatment plant (STP) on aquatic insect emergence and wintering insectivorous birds in a Swiss stream. At sites downstream of the STP, a combination of nutrient (phosphorus), organic (biochemical oxygen demand), and thermal pollution led to higher aquatic emergence compared to upstream sites (6× higher). In turn, the higher emergence led to a strong aggregational response by wintering insectivorous birds (8× higher linear densities compared to upstream sites). Polluted sites also had a different bird assemblage, which included rare wintering species that forage largely on aerial insects. A comparison between the polluted (downstream) sites and a nearby unpolluted stream produced similar differences. The magnitude and consistency of the effects illustrate how strongly stream alterations can propagate to birds through changes in aquatic emergence. Moreover, the results provide insights into the responses of linked stream-terrestrial food webs to other environmental issues that cause warming and/or pollution, including urbanization and climate change.
Collapse
|
4
|
Wood CL, Summerside M, Johnson PTJ. An effective method for ecosystem-scale manipulation of bird abundance and species richness. Ecol Evol 2019; 9:9748-9758. [PMID: 31534690 PMCID: PMC6745680 DOI: 10.1002/ece3.5509] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 06/05/2019] [Accepted: 07/08/2019] [Indexed: 12/02/2022] Open
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.
Collapse
Affiliation(s)
- Chelsea L. Wood
- School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashington
| | - Margaret Summerside
- Department of Ecology and Evolutionary BiologyUniversity of Colorado at BoulderBoulderColorado
| | - Pieter T. J. Johnson
- Department of Ecology and Evolutionary BiologyUniversity of Colorado at BoulderBoulderColorado
| |
Collapse
|
5
|
Mansor MS, Abdullah NA, Abdullah Halim MR, Md. Nor S, Ramli R. Diet of tropical insectivorous birds in lowland Malaysian rainforest. J NAT HIST 2018. [DOI: 10.1080/00222933.2018.1534015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Mohammad Saiful Mansor
- School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
| | - Nurul Ashikin Abdullah
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | | | - Shukor Md. Nor
- School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
| | - Rosli Ramli
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| |
Collapse
|
6
|
Nyffeler M, Şekercioğlu ÇH, Whelan CJ. Insectivorous birds consume an estimated 400-500 million tons of prey annually. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2018; 105:47. [PMID: 29987431 PMCID: PMC6061143 DOI: 10.1007/s00114-018-1571-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/08/2018] [Accepted: 06/11/2018] [Indexed: 11/20/2022]
Abstract
In this paper, we present an estimate of the predation impact of the global population of insectivorous birds based on 103 (for the most part) published studies of prey consumption (kg ha-1 season-1) of insectivorous birds in seven biome types. By extrapolation-taking into account the global land cover of the various biomes-an estimate of the annual prey consumption of the world's insectivorous birds was obtained. We estimate the prey biomass consumed by the world's insectivorous birds to be somewhere between 400 and 500 million metric tons year-1, but most likely at the lower end of this range (corresponding to an energy consumption of ≈ 2.7 × 1018 J year-1 or ≈ 0.15% of the global terrestrial net primary production). Birds in forests account for > 70% of the global annual prey consumption of insectivorous birds (≥ 300 million tons year-1), whereas birds in other biomes (savannas and grasslands, croplands, deserts, and Arctic tundra) are less significant contributors (≥ 100 million tons year-1). Especially during the breeding season, when adult birds feed their nestlings protein-rich prey, large numbers of herbivorous insects (i.e., primarily in the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera) supplemented by spiders are captured. The estimates presented in this paper emphasize the ecological and economic importance of insectivorous birds in suppressing potentially harmful insect pests on a global scale-especially in forested areas.
Collapse
Affiliation(s)
- Martin Nyffeler
- Section of Conservation Biology, Department of Environmental Sciences, University of Basel, CH-4056, Basel, Switzerland.
| | - Çağan H Şekercioğlu
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
- College of Sciences, Koç University, Rumelifeneri, Istanbul, Sariyer, Turkey
| | - Christopher J Whelan
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, 60607, USA
| |
Collapse
|
7
|
Fausch KD. Crossing boundaries: Shigeru Nakano’s enduring legacy for ecology. Ecol Res 2018. [DOI: 10.1007/s11284-017-1513-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
8
|
Fontaine B, Bergerot B, Le Viol I, Julliard R. Impact of urbanization and gardening practices on common butterfly communities in France. Ecol Evol 2016; 6:8174-8180. [PMID: 27878086 PMCID: PMC5108268 DOI: 10.1002/ece3.2526] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 11/17/2022] Open
Abstract
We investigated the interacting impacts of urban landscape and gardening practices on the species richness and total abundance of communities of common butterfly communities across France, using data from a nationwide monitoring scheme. We show that urbanization has a strong negative impact on butterfly richness and abundance but that at a local scale, such impact could be mitigated by gardening practices favoring nectar offer. We found few interactions among these landscape and local scale effects, indicating that butterfly‐friendly gardening practices are efficient whatever the level of surrounding urbanization. We further highlight that species being the most negatively affected by urbanization are the most sensitive to gardening practices: Garden management can thus partly counterbalance the deleterious effect of urbanization for butterfly communities. This holds a strong message for park managers and private gardeners, as gardens may act as potential refuge for butterflies when the overall landscape is largely unsuitable.
Collapse
Affiliation(s)
- Benoît Fontaine
- Département Ecologie et Gestion de la Biodiversité Muséum National d'Histoire Naturelle UMR 7204 - Conservation des espèces, suivi et restauration des populations, Centre d'Ecologie et des Sciences de la Conservation Paris France
| | | | - Isabelle Le Viol
- Département Ecologie et Gestion de la Biodiversité Muséum National d'Histoire Naturelle UMR 7204 - Conservation des espèces, suivi et restauration des populations, Centre d'Ecologie et des Sciences de la Conservation Paris France
| | - Romain Julliard
- Département Ecologie et Gestion de la Biodiversité Muséum National d'Histoire Naturelle UMR 7204 - Conservation des espèces, suivi et restauration des populations, Centre d'Ecologie et des Sciences de la Conservation Paris France
| |
Collapse
|
9
|
Valencia-Cuevas L, Tovar-Sánchez E. Oak canopy arthropod communities: which factors shape its structure? REVISTA CHILENA DE HISTORIA NATURAL 2015. [DOI: 10.1186/s40693-015-0045-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
10
|
Yoshikawa T, Osada Y. Dietary compositions and their seasonal shifts in Japanese resident birds, estimated from the analysis of volunteer monitoring data. PLoS One 2015; 10:e0119324. [PMID: 25723544 PMCID: PMC4344244 DOI: 10.1371/journal.pone.0119324] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 01/26/2015] [Indexed: 11/18/2022] Open
Abstract
Determining the composition of a bird’s diet and its seasonal shifts are fundamental for understanding the ecology and ecological functions of a species. Various methods have been used to estimate the dietary compositions of birds, which have their own advantages and disadvantages. In this study, we examined the possibility of using long-term volunteer monitoring data as the source of dietary information for 15 resident bird species in Kanagawa Prefecture, Japan. The data were collected from field observations reported by volunteers of regional naturalist groups. Based on these monitoring data, we calculated the monthly dietary composition of each bird species directly, and we also estimated unidentified items within the reported foraging episodes using Bayesian models that contained additional information regarding foraging locations. Next, to examine the validity of the estimated dietary compositions, we compared them with the dietary information for focal birds based on stomach analysis methods, collected from past literatures. The dietary trends estimated from the monitoring data were largely consistent with the general food habits determined from the previous studies of focal birds. Thus, the estimates based on the volunteer monitoring data successfully detected noticeable seasonal shifts in many of the birds from plant materials to animal diets during spring—summer. Comparisons with stomach analysis data supported the qualitative validity of the monitoring-based dietary information and the effectiveness of the Bayesian models for improving the estimates. This comparison suggests that one advantage of using monitoring data is its ability to detect dietary items such as fleshy fruits, flower nectar, and vertebrates. These results emphasize the potential importance of observation data collecting and mining by citizens, especially free descriptive observation data, for use in bird ecology studies.
Collapse
Affiliation(s)
- Tetsuro Yoshikawa
- Department of Forest Vegetation, Forestry and Forest Products Research Institute, Tsukuba, Japan
- * E-mail:
| | - Yutaka Osada
- Laboratory of Biodiversity Science, Graduate School of Agriculture and Life Science, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
11
|
Morrison EB, Lindell CA. Birds and bats reduce insect biomass and leaf damage in tropical forest restoration sites. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2012; 22:1526-1534. [PMID: 22908711 DOI: 10.1890/11-1118.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Both birds and bats are important insect predators in tropical systems. However, the relative influence of birds and bats on insect populations and their indirect effects on leaf damage have not previously been investigated in tropical forest restoration sites. Leaf damage by herbivorous insects can negatively affect the growth and survival of tropical plants and thus can influence the success of tropical forest restoration efforts. We used an exclosure experiment to examine the top-down effects of birds and bats on insects and leaf damage in a large-scale forest restoration experiment. Given the potential influence of tree planting design on bird and bat abundances, we also investigated planting design effects on bird and bat insectivory and leaf damage. The experiment included two planting treatment plots: islands, where trees were planted in patches, and plantations, where trees were planted in rows to create continuous cover. In both types of plots, insect biomass was highest on tree branches where both birds and bats were excluded from foraging and lowest on branches without exclosures where both birds and bats were present. In the island plots, birds and bats had approximately equal impacts on insect populations, while in plantations bats appeared to have a slightly stronger effect on insects than did birds. In plantations, the levels of leaf damage were higher on branches where birds and bats were excluded than on branches where both had access. In island plots, no significant differences in leaf damage were found between exclosure treatments although potential patterns were in the same direction as in the plantations. Our results suggest that both birds and bats play important roles as top predators in restoration systems by reducing herbivorous insects and their damage to planted trees. Tropical restoration projects should include efforts to attract and provide suitable habitat for birds and bats, given their demonstrated ecological importance.
Collapse
Affiliation(s)
- Emily B Morrison
- Department of Zoology and Center for Global Change and Earth Observations, Michigan State University, East Lansing, Michigan 48824, USA.
| | | |
Collapse
|
12
|
Böhm SM, Wells K, Kalko EKV. Top-down control of herbivory by birds and bats in the canopy of temperate broad-leaved oaks (Quercus robur). PLoS One 2011; 6:e17857. [PMID: 21483739 PMCID: PMC3070701 DOI: 10.1371/journal.pone.0017857] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 02/11/2011] [Indexed: 11/18/2022] Open
Abstract
The intensive foraging of insectivorous birds and bats is well known to reduce the density of arboreal herbivorous arthropods but quantification of collateral leaf damage remains limited for temperate forest canopies. We conducted exclusion experiments with nets in the crowns of young and mature oaks, Quercus robur, in south and central Germany to investigate the extent to which aerial vertebrates reduce herbivory through predation. We repeatedly estimated leaf damage throughout the vegetation period. Exclusion of birds and bats led to a distinct increase in arthropod herbivory, emphasizing the prominent role of vertebrate predators in controlling arthropods. Leaf damage (e.g., number of holes) differed strongly between sites and was 59% higher in south Germany, where species richness of vertebrate predators and relative oak density were lower compared with our other study site in central Germany. The effects of bird and bat exclusion on herbivory were 19% greater on young than on mature trees in south Germany. Our results support previous studies that have demonstrated clear effects of insectivorous vertebrates on leaf damage through the control of herbivorous arthropods. Moreover, our comparative approach on quantification of leaf damage highlights the importance of local attributes such as tree age, forest composition and species richness of vertebrate predators for control of arthropod herbivory.
Collapse
Affiliation(s)
- Stefan M Böhm
- Institute of Experimental Ecology, University of Ulm, Ulm, Germany.
| | | | | |
Collapse
|
13
|
Mäntylä E, Klemola T, Laaksonen T. Birds help plants: a meta-analysis of top-down trophic cascades caused by avian predators. Oecologia 2010; 165:143-51. [DOI: 10.1007/s00442-010-1774-2] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 08/27/2010] [Indexed: 11/27/2022]
|
14
|
MAZIA CNOEMI, CHANETON ENRIQUEJ, KITZBERGER THOMAS, GARIBALDI LUCASA. Variable strength of top-down effects inNothofagusforests: bird predation and insect herbivory during an ENSO event. AUSTRAL ECOL 2009. [DOI: 10.1111/j.1442-9993.2009.01933.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
15
|
|
16
|
Abstract
Predators affect herbivores directly and indirectly, by consumptive and nonconsumptive effects, and the combined influence of multiple predators is shaped by interactions among predators. I documented the individual and combined effects of birds (chickadees, nuthatches, warblers) and ants (Formica podzolica) on arthropods residing in pine (Pinus ponderosa) canopies in a factorial field experiment. Birds and ants removed herbivores but simultaneously benefited them by removing predatory arthropods. Birds and ants had net negative and positive effects, respectively, on the abundance of herbivore prey, supporting the notion that vertebrate predators have stronger negative effects on herbivores than do arthropod predators. Aphids (ant-tended and untended species) constituted three-quarters of herbivore biomass. The effect of birds on ant-tended aphids was twice that on untended aphid species or tended aphid species without ants. This was not due to there being more ant-tended aphids for birds to prey on; tended and untended aphid species were in similar abundances in the absence of birds. Instead, the effects of birds were strengthened by attributes of the mutualism that rendered tended aphids susceptible to predation. These dynamics led to nonadditive effects of birds and ants: birds only reduced tended aphid species and total herbivore abundances on trees with ants, while ants only increased tended aphid species and total herbivore abundances in the absence of birds. Consequently, top predators in this system only influenced total herbivore abundance when they disrupted an ant-aphid mutualism.
Collapse
Affiliation(s)
- Kailen A Mooney
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309-0334, USA.
| |
Collapse
|
17
|
RECHER HF, MAJER JD. Effects of bird predation on canopy arthropods in wandoo Eucalyptus wandoo woodland. AUSTRAL ECOL 2006. [DOI: 10.1111/j.1442-9993.2006.01555.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
18
|
Van Bael SA, Brawn JD. The direct and indirect effects of insectivory by birds in two contrasting Neotropical forests. Oecologia 2006; 145:658-668. [PMID: 16315345 DOI: 10.1007/s00442-005-0134-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A goal among community ecologists is to predict when and where trophic cascades occur. For example, several studies have shown that forest birds can limit arthropod abundances on trees, but indirect effects of bird predation (i.e. decreased arthropod damage to trees) are not always observed and their context is not well understood. Because productivity is one factor that is expected to influence trophic cascades, we compared the extent to which birds indirectly limit herbivore damage to trees in two lowland Neotropical forests that differed in seasonality of leaf production and rainfall. We compared the effects of bird predation on local arthropod densities and on damage to foliage through a controlled experiment using bird exclosures in the canopy and understory of two forests. We found that birds decreased local arthropod densities and leaf damage in the canopy of the drier site during periods of high leaf production, but not in the wetter forest where leaf production was low and sporadic throughout the year. Birds had no effect on arthropod abundances and leaf damage in the understory where leaf production and turnover rates were low. In support of these experimental interpretations, although we observed that arthropod densities were similar at the two sites, bird densities and the rate at which birds captured arthropods were greater at the drier, seasonally productive site. The influence of top-down predation by birds in limiting herbivorous insects appears to be conditional and most important when the production and turnover of leaves are comparatively high.
Collapse
Affiliation(s)
- S A Van Bael
- Dept. of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | | |
Collapse
|
19
|
Meehan TD, Lease HM, Wolf BO. Negative indirect effects of an avian insectivore on the fruit set of an insect-pollinated herb. OIKOS 2005. [DOI: 10.1111/j.0030-1299.2005.13578.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
20
|
Van Bael SA, Brawn JD. The direct and indirect effects of insectivory by birds in two contrasting Neotropical forests. Oecologia 2004; 143:106-16. [PMID: 15586294 DOI: 10.1007/s00442-004-1774-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Accepted: 11/03/2004] [Indexed: 10/26/2022]
Abstract
A goal among community ecologists is to predict when and where trophic cascades occur. For example, several studies have shown that forest birds can limit arthropod abundances on trees, but indirect effects of bird predation (i.e. decreased arthropod damage to trees) are not always observed and their context is not well understood. Because productivity is one factor that is expected to influence trophic cascades, we compared the extent to which birds indirectly limit herbivore damage to trees in two lowland Neotropical forests that differed in seasonality of leaf production and rainfall. We compared the effects of bird predation on local arthropod densities and on damage to foliage through a controlled experiment using bird exclosures in the canopy and understory of two forests. We found that birds decreased local arthropod densities and leaf damage in the canopy of the drier site during periods of high leaf production, but not in the wetter forest where leaf production was low and sporadic throughout the year. Birds had no effect on arthropod abundances and leaf damage in the understory where leaf production and turnover rates were low. In support of these experimental interpretations, although we observed that arthropod densities were similar at the two sites, bird densities and the rate at which birds captured arthropods were greater at the drier, seasonally productive site. The influence of top-down predation by birds in limiting herbivorous insects appears to be conditional and most important when the production and turnover of leaves are comparatively high.
Collapse
Affiliation(s)
- Sunshine A Van Bael
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | | |
Collapse
|
21
|
Philpott SM, Greenberg R, Bichier P, Perfecto I. Impacts of major predators on tropical agroforest arthropods: comparisons within and across taxa. Oecologia 2004; 140:140-9. [PMID: 15095089 DOI: 10.1007/s00442-004-1561-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2003] [Accepted: 03/19/2004] [Indexed: 10/26/2022]
Abstract
In food web studies, taxonomically unrelated predators are often grouped into trophic levels regardless of their relative importance on prey assemblages, multiple predator effects, or interactions such as omnivory. Ants and birds are important predators likely to differentially shape arthropod assemblages, but no studies have compared their effects on a shared prey base. In two separate studies, we excluded birds and ants from branches of a canopy tree ( Inga micheliana) in a coffee farm in Mexico for 2 months in the dry and wet seasons of 2002. We investigated changes in arthropod densities with and without predation pressure from (1) birds and (2) ant assemblages dominated by one of two ant species ( Azteca instabilis and Camponotus senex). We first analyzed individual effects of each predator (birds, Azteca instabilis, and C. senex) then used a per day effect metric to compare differences in effects across (birds vs ants) and within predator taxa (the two ant species). Individually, birds reduced densities of total and large arthropods and some arthropod orders (e.g., spiders, beetles, roaches) in both seasons. Azteca instabilis did not significantly affect arthropods (total, small, large or specific orders). Camponotus senex, however, tended to remove arthropods (total, small), especially in the dry season, and affected arthropod densities of some orders both positively and negatively. Predators greatly differed in their effects on Inga arthropods (for all, small, large, and individual orders of arthropods) both in sign (+/-) and magnitudes of effects. Birds had stronger negative effects on arthropods than ants and the two dominant ant species had stronger effects on arthropods in different seasons. Our results show that aggregating taxonomically related and unrelated predators into trophic levels without prior experimental data quantifying the sign and strengths of effects may lead to a misrepresentation of food web interactions.
Collapse
Affiliation(s)
- Stacy M Philpott
- Department of Ecology and Evolutionary Biology, University of Michigan, 830 N. University, Ann Arbor, MI 48109, USA.
| | | | | | | |
Collapse
|
22
|
Böhning-Gaese K, Lemoine N. Importance of Climate Change for the Ranges, Communities and Conservation of Birds. ADV ECOL RES 2004. [DOI: 10.1016/s0065-2504(04)35010-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
|
23
|
Van Bael SA, Brawn JD, Robinson SK. Birds defend trees from herbivores in a Neotropical forest canopy. Proc Natl Acad Sci U S A 2003; 100:8304-7. [PMID: 12832618 PMCID: PMC166224 DOI: 10.1073/pnas.1431621100] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most forest birds include arthropods in their diet, sometimes specializing on arthropods that consume plant foliage. Experimental tests of whether bird predation on arthropods can reduce plant damage, however, are few and restricted to relatively low-diversity systems. Here, we describe an experimental test in a diverse tropical forest of whether birds indirectly defend foliage from arthropod herbivores. We also compare how the indirect effects of bird predation vary with different levels of foliage productivity in the canopy vs. the understory. For three Neotropical tree species, we observed that birds decreased local arthropod densities on canopy branches and reduced consequent damage to leaves. In contrast, we observed no evidence of bird-arthropod limitation on conspecific saplings in the less productive understory of the same forest. Our results support theory that predicts trophic cascades where productivity is high and suggest that birds play an important role in Neotropical communities by means of their indirect defense of some canopy tree species.
Collapse
Affiliation(s)
- Sunshine A Van Bael
- Department of Animal Biology, University of Illinois at Urbana-Champaign, 606 East Healey Street, Champaign, IL 61820, USA.
| | | | | |
Collapse
|
24
|
|
25
|
Murakami M, Nakano S. Indirect effect of aquatic insect emergence on a terrestrial insect population through by birds predation. Ecol Lett 2002. [DOI: 10.1046/j.1461-0248.2002.00321.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
26
|
|
27
|
Nakano S, Murakami M. Reciprocal subsidies: dynamic interdependence between terrestrial and aquatic food webs. Proc Natl Acad Sci U S A 2001; 98:166-70. [PMID: 11136253 PMCID: PMC14562 DOI: 10.1073/pnas.98.1.166] [Citation(s) in RCA: 524] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutual trophic interactions between contiguous habitats have remained poorly understood despite their potential significance for community maintenance in ecological landscapes. In a deciduous forest and stream ecotone, aquatic insect emergence peaked around spring, when terrestrial invertebrate biomass was low. In contrast, terrestrial invertebrate input to the stream occurred primarily during summer, when aquatic invertebrate biomass was nearly at its lowest. Such reciprocal, across-habitat prey flux alternately subsidized both forest birds and stream fishes, accounting for 25.6% and 44.0% of the annual total energy budget of the bird and fish assemblages, respectively. Seasonal contrasts between allochthonous prey supply and in situ prey biomass determine the importance of reciprocal subsidies.
Collapse
Affiliation(s)
- S Nakano
- Center for Ecological Research, Kyoto University, Hirano, Kamitanakami, Otsu, Shiga 052-2113, Japan
| | | |
Collapse
|