Climate-driven declines in arthropod abundance restructure a rainforest food web

In the paper

“For example, the ruddy quail dove (Geotrygon montana), which eats grains and fruits almost exclusively, showed no decline in abundance between 1990 and 2015 at El Verde, while Todus mexicanus, the Puerto Rican tody, whose diet is composed entirely of insects (26), experienced a 90% reduction in catch rate.”

What the sources say

• Not checked yetcites [26] Reagan D Waide R 1996 The Food Web of a Tropical Rain Forest Univ of Chicago Press Chicago

In the paper

“First, from a single species of walking stick to a community of over 120 canopy taxa, long-term declines have occurred in parallel with rising temperatures.”

In the paper

“While average temperatures increased 8–10% over the same period, the proportion of extreme temperatures increased 14 times.”

In the paper

“Inclusion of mean daily rainfall as a covariate improved the UI for all analyses except for walking sticks, which had a UI of 100 without the covariate, and for the E. coqui at the Sonadura Old study site, which retained a low UI and indeterminate causal path with and without the covariate.”

In the paper

“Across all six populations, the average independent effect of MnMaxT on abundance was 25%, while the averages for four other temperature related variables ranged from 11.4 to 14.3%.”

In the paper

“Employing Willig et al.’s (24) census data, we also conducted quasi-Poisson regressions of walking stick abundance against time and against MnMaxT during the census periods (Fig. 5 C and D). Both regressions were negative and significant.”

What the sources say

• Not checked yetcites [24] Willig MR Presley SJ Bloch CP 2011 Long-term dynamics of tropical walking sticks in response to multiple large-scale and intense disturbances Oecologia 165 357 368 20677015 source

In the paper

“In July 1976, the canopy trap catch rate was 37 mg per trap per day compared with 5 mg per trap per day in July 2012, and 21 mg per trap per day in January 1976 vs. 8 mg per trap per day in January 2013.”

In the paper

“In the first phase, E. coqui numbers had a significant negative trend followed by a rapid increase during phase 2 from 6 to 57 individuals between January and October 1990, most likely due to immigration from surrounding areas following Hurricane Hugo. In phase 3, the population resumed a steady decline at about the same rate as phase 1, until the census ended 6 y later.”

In the paper

“Between 1978 and 2015, MnMaxT at El Verde rose by 2.0 °C at an average rate of 0.050 °C per year.”

In the paper

“However, the number of dry days (rainfall less than 1 mm) has been decreasing since 1975 (SI Appendix, Fig. S8G), while the variation in daily rainfall has been increasing (SI Appendix, Fig. S8H).”

In the paper

“The quasi-Poisson regressions of E. coqui numbers vs. time and MnMaxT for Stewart’s Activity Transect were both negative and significant (Fig. 7 A and B) (28).”

What the sources say

• Not checked yetcites [28] Stewart MM 1995 Climate driven population fluctuations in rain forest frogs J Herpetol 29 437 446 source

In the paper

“For the Sonadura Old population, only the regression of numbers on time was significant (P = 0.013), while the regression of abundance on temperature was marginally insignificant (P = 0.067).”

In the paper

“Compared with the earlier samples, arthropod biomass for July 2011–2012 and January 2012–2013 fell four and eight times, respectively.”

In the paper

“The regressions of E. coqui numbers vs. time and temperature for the Sonadura West study area were also negative and significant (SI Appendix, Fig. S3A).”

In the paper

“Between 1993 and 2015, the rate of temperature increase at Bisley Tower was 0.055 °C per year, not significantly different from the rate at El Verde.”

In the paper

“The density of A. gundlachi, the most common species, had dropped twice, and the density of A. evermanni declined 10 times.”

In the paper

“From 1975 to 2015, rainfall at the El Verde station averaged 3,653 mm/y with no significant positive or negative trends.”

In the paper

“Regressions on time were both negative and significant (SI Appendix, Fig. S3 C and D).”

In the paper

“The unanimity indices equaled 100 in five of the six groups, indicating that the causal path Temperature → Abundance is supported by all three of Vinod’s criteria for causality.”

In the paper

“the proportion of temperatures greater than 29 °C had both negative (El Verde E. coqui) and positive (walking sticks, E. coqui at Sonadura West and Sonadura Old) effects (SI Appendix, Table S5).”

What the sources say

• Not checked yetcites SI Appendix, Table S5

In the paper

“the canopy and walking stick censuses spanned three La Niña and three El Niño episodes.”

What the sources say

• Not checked yetcites SI Appendix, Fig. S9

In the paper

“As Janzen (3) pointed out, tropical species that evolved in comparatively aseasonal environments should have narrower thermal niches, reduced acclimation to temperature fluctuations, and exist at or near their thermal optima.”

What the sources say

• Not checked yetcites [3] Janzen D 1967 Why mountain passes are higher in the tropics Am Nat 101 233 249 source

In the paper

“Stewart and Woolbright (47), for example, estimated the E. coqui population alone harvested 114,000 prey items per hectare per night in the Luquillo forest, and Reagan and Waide (26) calculated that A. stratulus, A. gundlachi, and A. evermanni collectively consumed ∼443,300 invertebrates per hectare per day at El Verde.”

What the sources say

• Not checked yetcites [47] Stewart M Woolbright L 1996 Amphibians The Food Web of a Tropical Rain Forest Reagan DP Waide RB Univ of Chicago Press Chicago 363 398

In the paper

“Deutsch et al. (5) predicted that, for insects living at mid-to-high latitudes, rates of increase should grow as climate warms, while in the tropics insects should decline by as much as 20%.”

What the sources say

• Not checked yetcites [5] Deutsch CA 2008 Impacts of climate warming on terrestrial ectotherms across latitude Proc Natl Acad Sci USA 105 6668 6672 18458348 PMC2373333 source

In the paper

“This “counter cascade” conflicts with decades of research on trophic dynamics (44), as well as studies documenting the major impact of anoles, frogs, and birds on arthropod abundance (45, 46).”

What the sources say

• Not checked yetcites [44] Terborgh J Estes J 2010 Trophic Cascades: Predators, Prey, and the Changing Dynamics of Nature Island Press Washington, DC 2nd Ed
• Not checked yetcites [45] Pacala S Roughgarden J 1984 Control of arthropod abundance by Anolis lizards on St. Eustatius (Neth. Antilles) Oecologia 64 160 162 28312332 source
• Not checked yetcites [46] Marquis R Whelan C 1994 Insectivorous birds increase growth of white oak through consumption of leaf-chewing insects Ecology 75 2007 2014 source

In the paper

“This indicates that positive SOI values (La Niña episodes) have an immediate positive impact on the abundance of canopy invertebrates, and negative SOI values (El Niño episodes) have an immediate negative impact.”

In the paper

“These predictions have been verified in a variety of tropical reptiles, amphibians, and invertebrates (4–8).”

What the sources say

• Not checked yetcites [4] Whitfield SM 2007 Amphibian and reptile declines over 35 years at La Selva, Costa Rica Proc Natl Acad Sci USA 104 8352 8356 17449638 PMC1895953 source
• Not checked yetcites [5] Deutsch CA 2008 Impacts of climate warming on terrestrial ectotherms across latitude Proc Natl Acad Sci USA 105 6668 6672 18458348 PMC2373333 source
• Not checked yetcites [6] Huey RB 2009 Why tropical forest lizards are vulnerable to climate warming Proc Biol Sci 276 1939 1948 19324762 PMC2677251 source
• Not checked yetcites [7] Sinervo B 2010 Erosion of lizard diversity by climate change and altered thermal niches Science 328 894 899 20466932 source
• Not checked yetcites [8] Sunday J Bates A Dulvy N 2011 Global analysis of thermal tolerance and latitude in ectotherms Proc Biol Sci 278 1823 1830 21106582 PMC3097822 source

In the paper

“Second, the simultaneous declines of all 10 arthropod taxa in our sweep samples, the 10 most-abundant taxa in Schowalter’s (23) canopy samples, and arthropods occupying all strata of our forest study area, all point to an overriding environmental factor that has had ubiquitous, adverse effects on forest arthropods regardless of taxonomic affiliation, stratum occupied, or type of niche exploited.”

What the sources say

• Not checked yetcites [23] Schowalter TD 1994 Invertebrate community structure and herbivory in a tropical rain forest canopy in Puerto Rico following Hurricane Hugo Biotropica 26 312 319 source

In the paper

“Stewart and Woolbright (47), for example, estimated the E. coqui population alone harvested 114,000 prey items per hectare per night in the Luquillo forest, and Reagan and Waide (26) calculated that A. stratulus, A. gundlachi, and A. evermanni collectively consumed ∼443,300 invertebrates per hectare per day at El Verde.”

What the sources say

• Not checked yetcites [26] Reagan D Waide R 1996 The Food Web of a Tropical Rain Forest Univ of Chicago Press Chicago

In the paper

“We suggest that climate warming has emerged as such a dominant force affecting arthropod populations in the Luquillo forest and, most likely, in other tropical forests experiencing significant increases in ambient temperature.”

In the paper

“Their statistical models largely eliminated land-use change as an explanatory variable but did not thoroughly analyze a number of climate-change variables.”

What the sources say

• Not checked yetcites [61] Hallmann CA 2017 More than 75 percent decline over 27 years in total flying insect biomass in protected areas PLoS One 12 e0185809 29045418 PMC5646769 source

In the paper

“Decreases in Puerto Rico’s Eleutherodactylus populations began in the 1970s, with three species classified as threatened by 1985 (64).”

What the sources say

• Not checked yetcites [64] Joglar R Burrowes P 1996 Declining amphibian populations in Puerto Rico. Contributions to West Indian Herpetology: A Tribute to Albert Schwartz, Contributions to Herpetology, eds Powell R, Henderson RW (The Society for the Study of Amphibians and Reptiles, Ithaca, NY), Vol 12, pp 371–380

In the paper

“Increases in average temperature had a positive influence on insect biomass, an effect predicted by Tewksbury et al. (62) for temperate insects.”

What the sources say

• Not checked yetcites [61] Hallmann CA 2017 More than 75 percent decline over 27 years in total flying insect biomass in protected areas PLoS One 12 e0185809 29045418 PMC5646769 source
• Not checked yetcites [62] Tewksbury JJ Huey RB Deutsch CA 2008 Ecology. Putting the heat on tropical animals Science 320 1296 1297 18535231 source

In the paper

“Huey et al. (6) proposed that thermal-conforming lizards inhabiting shaded tropical forests should be especially vulnerable to climate warming.”

What the sources say

• Not checked yetcites [6] Huey RB 2009 Why tropical forest lizards are vulnerable to climate warming Proc Biol Sci 276 1939 1948 19324762 PMC2677251 source

In the paper

“At Monteverde, Costa Rica, populations of Anolis tropidolepis and Anolis altae were diminishing by 4.4% and 3.1% per year, respectively, for 11 and 13 y before both species became locally extinct.”

What the sources say

• Not checked yetcites [63] Pounds J Fogden M Campbell J 1999 Biological response to climate change on a tropical mountain Nature 398 611 615 source

In the paper

“In an encompassing study spanning local extinctions of lizard populations on five continents, Sinervo et al. (7) reached broadly similar conclusions for baskers and thermal-conformers in temperate and tropical habitats.”

What the sources say

• Not checked yetcites [7] Sinervo B 2010 Erosion of lizard diversity by climate change and altered thermal niches Science 328 894 899 20466932 source

In the paper

“This vulnerability results from lower critical thermal maxima than basking species, limited acclimation via thermoregulation, and reduced thermal safety margins.”

What the sources say

• Not checked yetcites [6] Huey RB 2009 Why tropical forest lizards are vulnerable to climate warming Proc Biol Sci 276 1939 1948 19324762 PMC2677251 source

In the paper

“Other studies have also documented declines in arthropod abundance across a broad range of geography, habitats, and taxa (10–12, 54, 55, 56–58).”

What the sources say

• Not checked yetcites [10] Conrad M Warren B Fox R Parsons M Woiwoda I 2006 Rapid declines of common, widespread British moths provide evidence of an insect biodiversity crisis Biol Conserv 132 279 291 source
• Not checked yetcites [11] Forister ML 2010 Compounded effects of climate change and habitat alteration shift patterns of butterfly diversity Proc Natl Acad Sci USA 107 2088 2092 20133854 PMC2836664 source
• Not checked yetcites [12] Brooks D 2012 Large carabid beetle declines in a United Kingdom monitoring network increases evidence for a widespread loss in insect biodiversity J Appl Ecol 49 1009 1019 source
• Not checked yetcites [54] Kotze DJ O’Hara RB 2003 Species decline—But why? Explanations of carabid beetle (Coleoptera, Carabidae) declines in Europe Oecologia 135 138 148 12647113 source
• Not checked yetcites [55] Thomas JA 2004 Comparative losses of British butterflies, birds, and plants and the global extinction crisis Science 303 1879 1881 15031508 source

In the paper

“The ongoing losses of anuran biodiversity on Puerto Rico and other West Indian islands (66, 67) are part of a global amphibian decline that has continued largely unabated since at least the 1970s (68–72).”

What the sources say

• Not checked yetcites [66] Burrowes P Joglar R Green D 2004 Potential causes for amphibian declines in Puerto Rico Herpetologica 60 141 154 source
• Not checked yetcites [67] Hedges S 1993 Global amphibian declines: A perspective from the Caribbean Biodivers Conserv 2 290 303 source
• Not checked yetcites [68] Pounds JA 1990 Disappearing gold BBC Wildlife 8 812 817
• Not checked yetcites [69] Pounds JA 1991 Amphibian watch: New clues in the case of the disappearing amphibians Wildlife Conservation 94 16 18
• Not checked yetcites [70] Barinaga M 1990 Where have all the froggies gone? Science 247 1033 1034 17800052 source
• Not checked yetcites [71] Crawford AJ Lips KR Bermingham E 2010 Epidemic disease decimates amphibian abundance, species diversity, and evolutionary history in the highlands of central Panama Proc Natl Acad Sci USA 107 13777 13782 20643927 PMC2922291 source
• Not checked yetcites [72] Pounds JA Fogden MPL Savage J Gorman G 1997 Tests of null models for amphibian declines on a tropical mountain Conserv Biol 11 1307 1322 source

In the paper

“while we propose that reduced consumption and declines in abundance result directly from climate-driven declines in food abundance.”

In the paper

“As climate warms, lizards should increasingly become nutritionally challenged, resulting in reduced body condition, growth rates, egg production, fat body mass, physical performance, and immune system response.”

In the paper

“Pounds and coworkers (63, 73, 77–79) have presented a wide-ranging body of evidence indicating that climate warming is a central factor promoting outbreaks of Batrachochytrium and the mass die-offs that follow.”

What the sources say

• Not checked yetcites [63] Pounds J Fogden M Campbell J 1999 Biological response to climate change on a tropical mountain Nature 398 611 615 source
• Not checked yetcites [73] Pounds JA 2006 Widespread amphibian extinctions from epidemic disease driven by global warming Nature 439 161 167 16407945 source
• Not checked yetcites [77] Pounds JA Crump ML 1994 Amphibian declines and climate disturbance: The case of the golden toad and the harlequin frog Conserv Biol 8 72 85 source
• Not checked yetcites [78] Pounds JA Carnaval AC Puschendorf R Haddad CFB Masters KL 2006 Responding to amphibian loss Science 314 1541 1542 17158306 source
• Not checked yetcites [79] Pounds JA 2001 Climate and amphibian declines Nature 410 639 640 11287931 source

In the paper

“While B. dendrobatidis has been detected in E. coqui populations at higher elevations in Puerto Rico (66, 75), the fungus is restricted to areas above 600 m (76)”

What the sources say

• Not checked yetcites [66] Burrowes P Joglar R Green D 2004 Potential causes for amphibian declines in Puerto Rico Herpetologica 60 141 154 source
• Not checked yetcites [75] Burrowes P Longo A Joglar R 2008 Geographic distribution of Batrachochytrium dendrobatidis in Puerto Rico Herpetol Rev 39 321 324
• Not checked yetcites [76] Longo AV Burrowes PA Joglar RL 2010 Seasonality of Batrachochytrium dendrobatidis infection in direct-developing frogs suggests a mechanism for persistence Dis Aquat Organ 92 253 260 21268989 source

In the paper

“Consequently, death rates from starvation, predation, and disease should increase along with concomitant decreases in reproduction.”

In the paper

“Most research has focused on the fungus Batrachochytrium dendrobatidis, which has precipitated mass-mortality events and catastrophic reductions in over 200 frog species world-wide (63, 73, 74).”

What the sources say

• Not checked yetcites [63] Pounds J Fogden M Campbell J 1999 Biological response to climate change on a tropical mountain Nature 398 611 615 source
• Not checked yetcites [73] Pounds JA 2006 Widespread amphibian extinctions from epidemic disease driven by global warming Nature 439 161 167 16407945 source
• Not checked yetcites [74] Catenazzi A 2015 State of the world’s amphibians Annu Rev Environ Resour 40 91 119 source

In the paper

“If climate warming is not driving arthropod declines, then whatever the factors may be, they must completely override the reduction in mortality from lowered predation levels.”

In the paper

“Overall, they found a 75% decline in biomass between 1989 and 2016.”

What the sources say

• Not checked yetcites [61] Hallmann CA 2017 More than 75 percent decline over 27 years in total flying insect biomass in protected areas PLoS One 12 e0185809 29045418 PMC5646769 source

In the paper

“To our knowledge, no studies have explored reductions in arthropod prey as a possible causal mechanism.”

In the paper

“Currently, 3 of the original 16 species of Puerto Rican Eleutherodactylus are considered extinct, and 13 species are listed as critically endangered, endangered, vulnerable, or near threatened (65).”

What the sources say

• Not checked yetcites [65] IUCN 2017 IUCN Red List of Threatened Species. Available at www.iucnredlist.org. Accessed May 25, 2017

In the paper

“Between 1923 and 1998 in Singapore, insectivores experienced the highest level of extinctions of any foraging guild (101)”

What the sources say

• Not checked yetcites [101] Castelletta M Sodhi NS Subaraj R 2000 Heavy extinctions of forest avifauna in Singapore: Lessons for biodiversity conservation in Southeast Asia Conserv Biol 14 1870 1880 35701951 source

In the paper

“Over a 20-y period, 54% of bird species native to Britain have also decreased (55).”

What the sources say

• Not checked yetcites [55] Thomas JA 2004 Comparative losses of British butterflies, birds, and plants and the global extinction crisis Science 303 1879 1881 15031508 source

In the paper

“We also note that in many studies of passerine declines, such as Mac Nally et al. (98), insectivores are often the group exhibiting the largest decreases in abundance, as appears to be the case in the Luquillo forest.”

What the sources say

• Not checked yetcites [98] Mac Nally R 2009 Collapse of an avifauna: Climate change appears to exacerbate habitat loss and degradation Divers Distrib 15 720 730 source

In the paper

“Galapagos finches provide a classic example of how climatic events associated with El Niño can lead to major fluctuations in food supplies, which in turn drive reductions in abundance of up to 40% per year in Geospiza populations (108).”

What the sources say

• Not checked yetcites [108] Grant B Grant P 1993 Evolution of Darwin’s finches caused by a rare climatic event Proc R Soc Lond 251 111 117 source

In the paper

“We found only two articles that ascribed the collapse of avian populations to the impact of climate warming on prey abundance.”

In the paper

“in the Guanica dry forest in southwestern Puerto Rico mist-net data indicate that dry season bird populations dropped by two-thirds over two decades (86).”

What the sources say

• Not checked yetcites [86] Faaborg J 2013 Long-term decline of a winter-resident bird community in Puerto Rico Biodivers Conserv 22 63 75 source

In the paper

“From data gathered over 55 y and 16 locations in Puerto Rico, the National Weather Service found that temperatures during La Niña events averaged ∼2.0 °C lower during the dry season (December to August), and 1.5 °C lower during the wet season (May to November) compared with El Niño episodes.”

What the sources say

• Not checked yetcites National Weather Service

In the paper

“The relationship between chytrid outbreaks and climate is complex, but in general epidemics are often associated with repeated warm years and drier weather.”

In the paper

“In montane habitats upward migrations into cooler refugia can spell the difference between survival and extinction as temperatures rise at lower elevations (119).”

What the sources say

• Not checked yetcites [119] Colwell RK Brehm G Cardelús CL Gilman AC Longino JT 2008 Global warming, elevational range shifts, and lowland biotic attrition in the wet tropics Science 322 258 261 18845754 source

In the paper

“Based on our literature searches, no studies have explored reductions in arthropod prey as a possible causal mechanism behind amphibian declines, nor the possibility that malnutrition could interact with rising temperature and drought, compounding the impacts of disease through depression of immunocompetence (83).”

What the sources say

• Not checked yetcites [83] Blaustein AR 2012 Ecophysiology meets conservation: Understanding the role of disease in amphibian population declines Philos Trans R Soc Lond B Biol Sci 367 1688 1707 22566676 PMC3350657 source

In the paper

“However, altitudinal shifts can also cause rapid changes in community structure, disrupting coevolved interactions, creating “no-analogue communities,” and contributing to community disassembly via accelerated extinctions (120, 121).”

What the sources say

• Not checked yetcites [120] Sheldon KS Yang S Tewksbury JJ 2011 Climate change and community disassembly: Impacts of warming on tropical and temperate montane community structure Ecol Lett 14 1191 1200 21978234 source
• Not checked yetcites [121] Urban MC Tewksbury JJ Sheldon KS 2012 On a collision course: Competition and dispersal differences create no-analogue communities and cause extinctions during climate change Proc Biol Sci 279 2072 2080 22217718 PMC3311897 source

In the paper

“In Canada and the northeastern United States, the total reduction in aerial insectivores between 1970 and 2010 was greater than 60%, the largest decline of all passerines analyzed (84, 99).”

What the sources say

• Not checked yetcites [84] Berlanga H 2010 Saving Our Shared Birds: Partners in Flight Tri-National Vision for Landbird Conservation Cornell Lab of Ornithology Ithaca, NY
• Not checked yetcites [99] North American Bird Conservation Initiative Canada 2012 The State of Canada’s Birds, 2012. Available at stateofcanadasbirds.org/. Accessed October 1, 2016

In the paper

“If these predictions are realized, the impact on food webs and ecosystems will be even more rapid than expected from the steady, linear increases in mean temperatures that are currently ravaging the natural world.”

In the paper

“Bird populations in many tropical and temperate ecosystems have been declining in parallel with those in Puerto Rico.”

In the paper

“ENSO also impacts rainfall across Puerto Rico, increasing dry season precipitation by 13% during El Niño years and causing a 14% increase in wet season precipitation during La Niña years.”

What the sources say

• Not checked yetcites National Weather Service

In the paper

“While we have focused on population collapse driven by climate change, shifts in altitudinal distributions of arthropods, insectivores, producers, and top predators may also play an important role in the observed declines in abundance.”

In the paper

“Diffenbaugh et al. (115) predicted a two- to threefold increase in the probability of historically unprecedented maximum daily temperatures between 2018 and 2036, and a three- to fivefold increase between 2036 and 2055.”

What the sources say

• Not checked yetcites [115] Diffenbaugh NS Singh D Mankin JS 2018 Unprecedented climate events: Historical changes, aspirational targets, and national commitments Sci Adv 4 eaao3354 29457133 PMC5812734 source

In the paper

“Anomalous rises in seawater temperature associated with ENSO have also caused severe reductions in food supplies, leading to starvation and mass mortality of marine birds (109–111).”

What the sources say

• Not checked yetcites [109] Piatt J Van Pelt T 1997 Mass-mortality of Guillemots (Uria aalge) in the Gulf of Alaska in 1993 Mar Pollut Bull 34 656 662 source
• Not checked yetcites [110] Ayala L Paz-Soldan L Garate P 2013 A mass mortality event of sooty shearwaters (Puffinus griseus) on the central coast of Peru Notornis 60 258 261 source
• Not checked yetcites [111] Fuentes H Antonietti E 1989 Efectos del Fenómeno El Niño en las aves marinas del litoral peruano Boletín Estudio Regional del Fenómeno El Niño 29 19 26

In the paper

“More recently, ocean warming associated with climate change has precipitated bottom-up trophic cascades, analogous to those proposed here for terrestrial systems, which have restructured both benthic and pelagic food webs and driven declines in shearwaters and auklets (112–114).”

What the sources say

• Not checked yetcites [112] Veit R McGowan J Ainley D Wahland T Pyle P 1997 Apex marine predator declines ninety percent in association with changing oceanic climate Glob Change Biol 3 23 28 source
• Not checked yetcites [113] Baduini C 2001 Mass mortality of short-tailed shearwaters in the south-eastern Bering Sea during summer 1997 Fish Oceanogr 10 117 130 source
• Not checked yetcites [114] Springer A Byrd G Iverson S 2007 Hot oceanography: Planktivorous seabirds reveal ecosystem responses to warming of the Bering Sea Mar Ecol Prog Ser 352 289 297 source

In the paper

“In Canada, 44% of 460 bird species have had negative trends since 1970, and 42 species common to the United States, Canada, and Mexico have lost 50% or more of their populations in 40 y (84).”

What the sources say

• Not checked yetcites [84] Berlanga H 2010 Saving Our Shared Birds: Partners in Flight Tri-National Vision for Landbird Conservation Cornell Lab of Ornithology Ithaca, NY

In the paper

“They attributed the ongoing declines to the impact of increasing temperatures and decreasing rainfall on arthropods and other food resources.”

What the sources say

• Not checked yetcites [98] Mac Nally R 2009 Collapse of an avifauna: Climate change appears to exacerbate habitat loss and degradation Divers Distrib 15 720 730 source

In the paper

“Pearce-Higgins et al. (97) also analyzed the diets of 17 upland, insectivorous bird species in the United Kingdom, calculated a climate-sensitivity index for their prey, and showed that the index was correlated with recent negative population trends.”

What the sources say

• Not checked yetcites [97] Pearce-Higgins J Dennis P Whittingham M Yalden D 2010 Impacts of climate on prey abundance account for fluctuations in a population of a northern wader at the southern edge of its range Glob Change Biol 16 12 23 source

In the paper

“In a lowland tropical rainforest at La Selva, Costa Rica, Sigel et al. (85) also found that at least 50% of declining bird species were insectivorous.”

What the sources say

• Not checked yetcites [85] Sigel BJ Sherry TW Young BE 2006 Avian community response to lowland tropical rainforest isolation: 40 years of change at La Selva Biological Station, Costa Rica Conserv Biol 20 111 121 16909664 source

In the paper

“Stapley et al. (20) reached a similar conclusion concerning the effects of ENSO on Anolis populations in Panama.”

What the sources say

• Not checked yetcites [20] Stapley J Garcia M Andrews RM 2015 Long-term data reveal a population decline of the tropical lizard Anolis apletophallus, and a negative affect of El Niño years on population growth rate PLoS One 10 e0115450 25671423 PMC4325001 source

In the paper

“Given ongoing climate change, the elevational range of Batrachochytrium will almost certainly change, as well as its impact on Puerto Rican frogs, especially juveniles (80).”

What the sources say

• Not checked yetcites [80] Langhammer PF Burrowes PA Lips KR Bryant SB Collins JP 2014 Susceptibility to the amphibian chytrid fungus varies with ontogeny in the direct-developing frog Eleutherodactylus coqui J Wildl Dis 50 438 446 24807186 source

In the paper

“The reductions in habitat area as species move up mountains also increase extinction rates (87), and can erode genetic diversity, further reducing fitness and response to ongoing changes in climate (122, 123).”

What the sources say

• Not checked yetcites [87] Sekercioglu C Primack R Wormworth J 2012 The effects of climate change on tropical birds Biol Conserv 148 1 18 source
• Not checked yetcites [122] Arenas M Ray N Currat M Excoffier L 2012 Consequences of range contractions and range shifts on molecular diversity Mol Biol Evol 29 207 218 21778191 source
• Not checked yetcites [123] Rubidge EM 2012 Climate-induced range contraction drives genetic erosion in an alpine mammal Nat Clim Chang 2 285 288 source

In the paper

“Pearce-Higgins et al. (97) analyzed the demographics of the golden plover in Europe and showed that trends in population dynamics were closely associated with temperature-based reductions in prey abundance.”

What the sources say

• Not checked yetcites [97] Pearce-Higgins J Dennis P Whittingham M Yalden D 2010 Impacts of climate on prey abundance account for fluctuations in a population of a northern wader at the southern edge of its range Glob Change Biol 16 12 23 source

In the paper

“In the rainforest at La Selva, Costa Rica, 10–20% of resident birds declined between 1960 and 1999 (85)”

What the sources say

• Not checked yetcites [85] Sigel BJ Sherry TW Young BE 2006 Avian community response to lowland tropical rainforest isolation: 40 years of change at La Selva Biological Station, Costa Rica Conserv Biol 20 111 121 16909664 source

In the paper

“Numerous studies have documented the impact of the ENSO on all of the major taxa considered here, including invertebrates (116), frogs (63, 73, 77, 117), lizards (1, 5), and birds (118).”

What the sources say

• Not checked yetcites [116] Gutiérrez-Fonseca PE Ramírez A Pringle CM 2018 Large-scale climatic phenomena drive fluctuations in macroinvertebrate assemblages in lowland tropical streams, Costa Rica: The importance of ENSO events in determining long-term (15y) patterns PLoS One 13 e0191781 29420548 PMC5805265 source
• Not checked yetcites [63] Pounds J Fogden M Campbell J 1999 Biological response to climate change on a tropical mountain Nature 398 611 615 source
• Not checked yetcites [73] Pounds JA 2006 Widespread amphibian extinctions from epidemic disease driven by global warming Nature 439 161 167 16407945 source

In the paper

“Nebel et al. (100) concluded that these declines resulted from impoverishment of flying insect populations, and suggested acid rain as a possible mechanism.”

What the sources say

• Not checked yetcites [100] Nebel S Mills A McCracken J Taylor P 2010 Declines of aerial insectivores in North America follow a geographic gradient Avian Conserv Ecol 5 1

In the paper

“An alternative to the climate-warming hypothesis for population declines in Luquillo and other tropical montane habitats is a mechanism proposed by Lawton et al. (126).”

What the sources say

• Not checked yetcites [126] Lawton RO Nair US Pielke RA Sr Welch RM 2001 Climatic impact of tropical lowland deforestation on nearby montane cloud forests Science 294 584 587 11641496 source

In the paper

“Our analyses provide strong support for the hypothesis that climate warming has been a major factor driving reductions in arthropod abundance, and that these declines have in turn precipitated decreases in forest insectivores in a classic bottom-up cascade.”

In the paper

“Because all dispersion tests rejected the null hypothesis, only quasi-Poisson regressions were used.”

What the sources say

• Not checked yetcites [148] Kleiber C Zeileis A 2008 Applied Econometrics with R (Springer, New York), Available at https://cran.r-project.org/web/packages/AER/index.html. Accessed June 1, 2016 source

In the paper

“Climate variables are often highly correlated and can generate spurious results when used in regression (34, 134).”

What the sources say

• Not checked yetcites [34] Mac Nally R 2002 Multiple regression and inference in ecology and conservation biology: Further comments on identifying important predictor variables Biodivers Conserv 11 1397 1401 source
• Not checked yetcites [134] Knape J de Valpine P 2011 Effects of weather and climate on the dynamics of animal population time series Proc Biol Sci 278 985 992 20880886 PMC3049023 source

In the paper

“We did not utilize automated regression techniques, such as stepwise selection and backward elimination, due to a variety of issues including erroneous type I error rates and inflated R2 measures (33).”

In the paper

“This hypothesis also provides a parsimonious explanation for why similar cross-taxa, concordant decreases in reptiles, anurans, and birds have occurred in Costa Rican rainforests (3, 63), and are likely occurring across a broad range of tropical ecosystems.”

What the sources say

• Not checked yetcites [3] Janzen D 1967 Why mountain passes are higher in the tropics Am Nat 101 233 249 source
• Not checked yetcites [63] Pounds J Fogden M Campbell J 1999 Biological response to climate change on a tropical mountain Nature 398 611 615 source

In the paper

“All multivariate quasi-Poisson regressions were then checked for multicollinearity using the Variance Inflation Factor and Bartlett’s Test of Sphericity.”

In the paper

“Given that the ruddy quail dove (G. montana) is an exclusive granivore (SI Appendix, Fig. S4) and could confound patterns in insectivore abundance, we excluded this species from counts of captured birds.”

What the sources say

• Not checked yetcites SI Appendix, Fig. S4

In the paper

“Because Akaike’s Information Criterion cannot be calculated for quasi-Poisson models, we selected models having the smallest deviance residuals and the lowest χ2 test statistic P values.”

In the paper

“Consequently, the degree of shade, cooling, and humidification of the habitats surrounding the Luquillo Mountains have all increased (128).”

What the sources say

• Not checked yetcites [128] Otero LM Huey RB Gorman GC 2015 A few meters matter: Local habitats drive reproductive cycles in a tropical lizard Am Nat 186 E72 E80 26655361 source

In the paper

“Since 1998, 8 of 33 Luquillo forest bird species (124) and 10 of 12 resident frog species (125) have undergone elevational shifts.”

What the sources say

• Not checked yetcites [124] Campos-Cerqueira M Arendt WJ Wunderle JM Jr Aide TM 2017 Have bird distributions shifted along an elevational gradient on a tropical mountain? Ecol Evol 7 9914 9924 29238525 PMC5723601 source
• Not checked yetcites [125] Campos-Cerqueira M Aide TM 2017 Lowland extirpation of anuran populations on a tropical mountain PeerJ 5 e4059 29158987 PMC5694215 source

In the paper

“For Woolbrights’s (29, 30) census data at the Sonadura Old study area, we removed one outlier for the 1995 census data when E. coqui numbers increased from 29 to 236 and returned to 45 individuals in the next census.”

What the sources say

• Not checked yetcites [29] Woolbright L 1991 Impact of Hurricane Hugo on forest frogs in Puerto Rico Biotropica 23 462 467 source
• Not checked yetcites [30] Woolbright L 1996 Disturbance influences long-term population patterns in the Puerto Rican frog, Eleutherodactylus coqui (Anura: Leptodactylidae) Biotropica 28 493 501 source

In the paper

“To guard against such effects of multicollinearity, we constructed correlation matrices of the HP predictors and eliminated variables having correlations of 0.7 or higher.”

In the paper

“Pounds et al. (63) have presented a detailed rebuttal of the Lawton scenario with respect to montane forests in Costa Rica.”

What the sources say

• Not checked yetcites [63] Pounds J Fogden M Campbell J 1999 Biological response to climate change on a tropical mountain Nature 398 611 615 source

In the paper

“Following the same procedures and using the same study area, arthropod abundances were again estimated during July 2011 and January 2012 using both sticky-traps and sweep netting.”

What the sources say

• Not checked yetcites [22] Lister BC 1981 Seasonal niche relationships of rainforest anoles Ecology 62 1548 1560 source

In the paper

“We conducted our field work in the same study area utilized by Lister (22) in the 1970s.”

What the sources say

• Not checked yetcites [22] Lister BC 1981 Seasonal niche relationships of rainforest anoles Ecology 62 1548 1560 source

In the paper

“However, Luquillo forest birds and frogs are known to exhibit elevational range shifts similar to those encountered on other tropical mountains.”

What the sources say

• Not checked yetcites [124] Campos-Cerqueira M Arendt WJ Wunderle JM Jr Aide TM 2017 Have bird distributions shifted along an elevational gradient on a tropical mountain? Ecol Evol 7 9914 9924 29238525 PMC5723601 source
• Not checked yetcites [125] Campos-Cerqueira M Aide TM 2017 Lowland extirpation of anuran populations on a tropical mountain PeerJ 5 e4059 29158987 PMC5694215 source

In the paper

“Hence, we eliminated 2 of the 11 climate variables that had the highest correlations with the other climate variables.”

In the paper

“In theory, clear cutting of lowland forests raises surface temperature, which in turn increases conductive heat flux from exposed ground to the atmosphere. This reduces both evapotranspiration and evaporative cooling (126) and lowers humidity.”

What the sources say

• Not checked yetcites [126] Lawton RO Nair US Pielke RA Sr Welch RM 2001 Climatic impact of tropical lowland deforestation on nearby montane cloud forests Science 294 584 587 11641496 source