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Patterns of Seasonal and Altitudinal Change in Monteverde Bird Communities

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Patterns of Seasonal and Altitudinal Change in Monteverde Bird Communities
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Marlene ( )
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Palm, Eric
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Birds--Behavior   ( lcsh )
Climatic changes--Environmental aspects   ( lcsh )
Costa Rica--Puntarenas--Monteverde Zone--Monteverde   ( lcsh )
Aves--Comportamiento
Cambios climáticos--Aspectos ambientales
Costa Rica--Puntarenas--Zona de Monteverde--Monteverde
Tropical Ecology Fall 2003
Ecología Tropical Otoño 2003
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Reports   ( lcsh )
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Previous studies in Monteverde, Costa Rica, have shown that numerous bird species are moving upslope in response to climate change. While there are an increasing number of such studies that address climate change, most fail to incorporate seasonal climatic variation. I censused the birds in three elevational zones in the Monteverde area not only to assess these distributional shifts, but also to determine the effects of season on bird communities. Compared to Michael Fogden’s data from 1979-1992, I found a number of species that have moved into higher zones where they were previously less common or absent. However, the results showed less upslope movement than those found by Donnelly (1998), during the dry season, likely due to downslope migrations during the non-breeding season. My findings suggest that not only are birds continuing to move up in elevation, but also that the effects of global warming on such movements in birds are less pronounced during the wet season than in the dry season. Also, this study indicates that future studies of species responses to climate change must account for seasonal variation.
Abstract:
Marlene
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Text in English.
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Patterns of Seasonal and Altitudinal Change in Monteverde Bird Communities Eric Palm Department of Biology, The Colorado College _____________________________________________________________________________________ ABSTRACT Previous studies in Monteverde, Costa Rica, have shown that numerous bird species are moving upslope in response to climate change. While there are an increasing number of such studies that address climate change, most fail to incorporate seasonal climatic variation. I censused the birds in three elevational zones in the Monteverde area not only to assess these distributional shifts, but also to determine the effects of season on bird communities. Compared 1992, I found a number of species that have moved into higher zones where they were previously less common or absent. However, the results showed less upslope movement than those found by Donnelly (1998), during the dry season, likely due to downslope migrations during th e non breeding season. My findings suggest that not only are birds continuing to move up in elevation, but also that the effects of global warming on such movements in birds are less pronounced during the wet season than in the dry season. Also, this study indicates that future studies of species responses to climate change must account for seasonal variation. RESUMEN Estudios anteriores en Monteverde, Costa Rica, ha mostrado que muchas especies de aves estn subiendo hasta elevaciones ms altas debido al cambio climtico. Hice un censo de las aves en tres zonas a diferentes elevaciones en Monteverde para evaluar estos cambios en distribucin y para determinar los efectos de las estaciones en las comunidades de aves. En comparacin con los datos de Michael Fogden de 1979 1992, este estudio descubri que cierto nmero de especies se ha movido hasta zonas ms altas donde anteriormente eran menos comunes o estaban completamente ausentes. Sin embargo, los resultados mostraron menos movimiento ascendente que lo s que fueron encontrados por Donnelly (1998) durante la estacin seca, probablemente debido a las migraciones hasta elevaciones ms bajas durante la poca no reproductiva. Los resultados sugieren que las aves no solamente estn movindose hacia arriba en e levacin, sino que tambin los efectos del calentamiento global en estos movimientos son menos pronunciados durante la estacin lluviosa que durante la estacin seca. Tambin, este estudio indica que futuros estudios en la respuesta de las especies a cambi os climticos necesitan considerar la variacin estacional. INTRODUCTION Scientists are beginning to notice dramatic shifts in the distribution and abundance of birds, as well as many other taxa all around the world (Pounds et al. 1999 and Walther, 2002) A large portion of these changes, at the community and ecosystem level, has been attributed to global warming, generally occurring in a timeframe much too short to blame on any kind of evolution (Pounds et al. 1999). Such observations are most often made on a local or regional scale, and the changes observed are more pronounced in certain areas due to local climatic variation (Walther, 2002). Climate change has been shown to affect the distribution of many plants and insects on which birds depend for food thus causing additional changes in bird distributions (Janzen, 1983). In Monteverde, Costa Rica, changes in climate are most noticeable on the highly seasonal Pacific slope, an area most affected by the recent increase in frequency of El Nio episodes tha t have led to warmer and drier conditions (Pounds and Crump, 1994). Since 1972, Monteverde has experienced an increase in the number of completely dry days during the dry season from January through May (Pounds et al. 1999). In April and May of 1998, Donn elly conducted a study assessing elevational changes in bird

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species distribution and abundance. The goal of the study was to compare species An Annotated Checklist of the Birds of Montever de and Peas Blancas which showed that the specific habitat used by a bird species in the area was largely dependent on both elevation and season (Fogden, 1993). This checklist defined four major altitudinal zones on the Pacific Slope of the region, and c lassified bird species based on relative abundance in each zone using data collected from 1979 (1993), but richness decreased by 11 species in Zone 2 and increased by 12 species in Zone 4. This agre ed with Pounds et al. (1999), who also observed upslope movement of birds (Keel billed Toucan and Golden crowned Warbler). However, there has been no study conducted during the wet season to determine inter season variability in abundance and distribution in the Monteverde area. Generally, Costa Rican birds show an upslope movement during the dry season followed by a downslope movement during the wet season in response to seasonal variation in resource availability (Janzen, 1983). season pattern of upward movement may simply reflect a more general pattern of seasonal altitudinal migration with shifting resource abundance. My study attempted to determine if there were any upward shifts in bird species distributions in response to cl imate change in the Monteverde area during the wet season, dry and wet seasons. It is possible that trends observed by previous studies in the area are actually more of a r esult of seasonality than overall climate change. Because of the above mentioned seasonal migrations in Costa Rican birds, I hypothesized that a census of Monteverde bird species during the wet season would show less upslope movement than a similar study c onducted during the dry season. In addition, I attempted to provide the first quantitative approach to placing Monteverde bird species into abundance categories. MATERIALS AND METHODS From 1100m to above 1600m, representing areas from premontane wet to l ower montane rain Holdridge Life Zones, birds were censused in order to determine any differences found would most likely be due to seasonality t han to non seasonal climate change. (1993) data by surveying the same forested areas that have remained relatively unchanged. Observations were made in the area surround ing Monteverde, Costa Rica, including nearby Santa Elena. I worked in six different observational sites, each containing both forest and open areas. Each site was placed into one of three Fogden Zones. Zone 2, 1300m to 1500m, consisted of Bajo del Tigre Re serve and the Finca Ecolgica Monteverde, and is part of the premontane wet forest. Forests and open areas of the Estacin Biolgica Monteverde and the Monteverde Cloud Forest Preserve were

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used as observational sites for both Zone 3, 1500m to 1600m, and Z one 4, 1600m and above. Zone 3 is classified as lower montane wet forest life zone, while Zone 4 is an example of lower montane rainforest. Observations were made from October 18 to November 14, 2003 between 6:00 am and 10:00am for a total of 21 hours in the forested areas and 7 hours in the open areas of each zone. I spent less time in open areas based upon my previous observations that these areas were generally less species rich and birds in open areas were more easily seen than in nearby forests. I use d binoculars and A Guide to the Birds of Costa Rica to identify each individual bird by both sight and call. For those calls I was not familiar with, I identified individuals using a tape recorder to compare recordings with those on either one of three bir dcall audio CDs (Cornell Laboratory of Ornithology, 1992, 1995, and 1997). For each zone, I compiled a list of all bird species found and the number of (1993) abundanc e categories by developing a quantitative range for each category. These species was observed 22 times or more in a zone, it was considered to be common (C) in that zone, which I approximated with a range of eight to 21 individuals observed during one week. Any bird observed between two to seven times was classified as uncommon (U), which Finally, or heard only one time during the week, and did not classify any birds that I did n ot see. Two flocking species, the Crimson fronted Parakeet and the Orange chinned Parakeet were both seen in very large numbers but were classified as uncommon, because they were only observed on three separate occasions each. My list is composed of all 1 55 species observed, plus 14 species observed by both Donnelly (1998) and Fogden (1993) that were not found on this study. It also includes another five species seen or heard by t to be absent during the dry season (see Appendix A). From the list, differences in distribution and in abundance were noted that were thought to be significant compared to data from both Fogden (1993) and Donnelly (1998). Two Chi squared tests were used to compare the distributions of all 155 bird find species turnover between zones. Beta diversity values range from zero to one, with larger values showing little species overlap or high species turnover between the two zones being compared. The number of habitats was two. To compare beta values to those of Fogden and Donnelly, nocturnal bir ds were excluded because no efforts were made to observe these birds.

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RESULTS Over 84 total hours of observation, I found 155 of the 261 bird species expected from (Table 1). From the remaining 128 species, a majority showed no change in distribution from previous studies, and there were also a limited number of species for which I di d not feel my data were sufficient to make any comparisons (see Appendix A). These 28 species showed more than one type of elevational shift. Seventeen had clearly moved Another six species demonstrated downslope movement from Donnelly (1998), but species moved downslope and in some cases completely out of the Monteverde region, as predicted for the non extremely common in Zone 3 duri ng this study. Any instances of strong downward shifts from Fogden distributions were said to occur in the wet season by the checklist. For example, I found the Black Guan to be fairly common in Zone 2. This species is listed in the checklist as a rare bir Zone 2 in the non listed as common in Zones 3 and 4, but were not found because they are known to be these zones and migrate downslope during the non breeding season (Fogden, 1993). Figure 1 shows the number of species found in each zone and those found by both Fogden (1993) and Donnelly (1998). The distribution was not significantly different than the e squared test (X 2 = 5.33, df = 2). (X 2 = 16.83, df = 2). Expected values were found by using the frequency distribution of eac h study to determine the number of species that would have been found per zone assuming a total of 155 species was found for all zones. Thus, it appears that birds are found closer to their historical ranges (those found by Fogden) during the wet season, a nd more pronounced upslope movements occur during the dry season. Beta diversity indices were calculated for all possible combinations of zones for an .04, but they were all considerably higher than those found by Donnelly. This suggests that there is greater species turnover and less overlap during the wet season, and that during this time, birds are found in more clearly defined ranges. DISCUSSION observations due to global warming, but downward migrations during the wet season lead lessen this upslope shift compared to the dry season. Twenty seven species provided

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stro ng evidence of upward movement in the last 10 20 years. Species either increased in billed Pigeon, Tropical Kingbird, Rufous and whit e Wren, Gray crowned Yellowthroat, Slate throated Redstart and Golden crowned Warbler all demonstrated strong upward distributional shifts in both this billed Toucan and Golden crowned Warbler, whic h also showed similar upslope movements in Pounds, et al. (1999). The Slate throated Redstart, previously absent from Zone 4, was found in only in its lower reaches. This finding is noteworthy because it is a common species that shares a similar niche to that of the Collared Redstart, another common species, which is only found in Zone 4 (Charnov et al. 1976). A recently study conducted in the Monteverde Cloud Forest Preserve showed that when these two species overlap in distribution, one is forced to chan ge its niche to avoid interspecific competition (Adams, 2003). The only possible explanation for the complete absence of Common Bush Tanagers in season, completely vacati ng Zone 3 before returning down to lower elevations again in the wet season. Finally, the Tennessee Warbler was unique in that it was the only species among numerous North American migrants that showed a strong upslope movement, with 19 individuals observe d in Zone 4, where it was previously undetected by Fogden (1993). This suggests that range shifts to higher elevations are not limited to resident species, but may apply to long distance Neotropical migrants as well. I did not attempt to make any conclusi ons about any birds that showed similar not find in sufficient numbers or completely missed due to chance, such as the Azure hooded Jay. It is well known that popu lations of species across many different taxa constantly fluctuate in numbers, and these fluctuations can even lead to local extinctions (Quammen, 1996). Therefore, it is possible that some birds that were missed might have declined in abundance. From my Chi squared results, I determined that the lack of significance between observed in some species, such movements were possibly less frequent during the wet season. However, th e Chi squared test showed a significant difference between my data versus 88, and fewer in Zone 3, 89 versus 102, and Zone 4, 65 versus 91. This clearly shows that move ment due to seasonality is very pronounced, with the biggest changes occurring in Zone 2 and Zone 4. show a consistent pattern, with all values being at least 0.07 higher in the wet season. A possible explanation could be that during the dry season, many bird species deviate from their which are often patchy in distribution and not zone specific (Borror et al. 1992). Thus, birds may be

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found over a wider variety of elevational zones during the dry season. This would create more overlap between zones, and a wider habitat breadth, leadin g to lower Beta value. In the wet season, such species may return to elevation specific ranges, causing less overlap between zones and a higher Beta value. Overall, the distributional shifts described by this study can be explained by both non seasonal cl imate changes and changes between seasons. The lack of any strong breeding altitudinal migrations (Black Guan, Resplendent Quetzal, Three wattled Bellbird) provides even more ev idence to support, if anything, a general non seasonal upslope movement of bird species in the Monteverde area. Because these shifts cannot be attributed to any kind of deforestation or other alterations of habitat, it is likely that recent climate change is responsible. My results show that in addition to these non seasonal movements, seasonal shifts are also very pronounced, where localized migrations have large effects on bird distribution. Of the 28 species that showed clear changes in distribution, ni ne species shifts can only be explained by non seasonal climate change (Keel billed Toucan, Gray headed Chachalaca), 12 can only be attributed to seasonality (Great tailed Grackle, Common Bush Tanager), and seven show both types of movement (Red billed Pig eon, Golden crowned Warbler). Global warming, and more specifically an increase in El Nio episodes, has led to a warming and drying affect in Monteverde, which is more pronounced during the dry season of December through May (Haber et al. 1996). Thus, it is no surprise that the data point to higher incidence of upward movement during this time period. This study shows that future work addressing climate change over a span of several years to several decades must be tempered by more short term, inter seaso nal differences in order to accurately assess the overall effect that non seasonal changes of climate have on bird species distributions. With this study, I attempted not only to provide the first quantitative approach to placing each bird species into abu ndance categories in the Monteverde area, but I tried to determine how much seasonal differences affect bird populations. Hopefully, future studies will continue these efforts in order to build upon these findings or to suggest new trends in the Monteverde bird community. ACKNOWLEDGEMENTS I would like to thank Dr. Alan Masters for originally suggesting the project and for his support throughout the entire process. I would also like to thank R. Andrew Rodstrom and Matthew Gasner for their constant help, ad vise, and humor. Thank you to the Monteverde Cloud Forest Preserve, the Monteverde Conservation League, the Monteverde Biological Station and the Monteverde Ecological Farm for allowing me to watch birds on their land, and a special thanks to my gracious h ost parents, Luis Alfredo Parajeles V. and Ana Virginia Rodriguez, who made me breakfast at 5:00 every morning. Finally, I would like to thank my parents, David and Mary Palm, for agreeing to finance my trip to Costa Rica. ________________________________ _____________________________________________________

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LITERATURE CITED Adams, Evan M. 2003. Niche partitioning and overlap in a cloud forest between two neotropical warblers (Parulidae). CIEE Spring Borror, Donald J., Charles A. Tripplehorn and Norman F. Johnson. 1992. An Introduction to the Study of Insects Harcourt Brace College Publishers, New York. Charnov, Eric L., Gordon H. Orians and Kim Hyatt. Ecological Implications of Resource Depression. 1976. American Naturalist 110: 247 259. Co rnell Laboratory of Ornithology. 1992. Voices of the Cloud Forest Library of Natural Sounds, Ithaca, New York. Cornell Laboratory of Ornithology. 1995. Voices of Costa Rican Birds. Library of Natural Sounds, Ithaca, New York. Cornell Laboratory of Ornitho logy. 1997. Indicator Birds of the Costa Rican Cloud Forest Library of Natural Sounds, Ithaca, New York. Donnelly, Elise. 1998. Changes in bird species composition in four habitat zones in Monteverde, Costa Rica. CIEE Spring. Fogden, Michael. 1993 An Ann otated Checklist of the Birds of Monteverde and Peas Blancas San Jos, Costa Rica. Haber, William A., Willow Zuchowski and Erick Bello. 1996. An Introduction to Cloud Forest Trees: Monteverde, Costa Rica La Nacin, San Jos, Costa Rica. Janzen Daniel H. 1983. Costa Rican Natural History University of Chicago, Chicago, IL. Pounds, Alan J. and Martha L. Crump. 1994. Amphibian Declines and Climate Disturbance: The Case of the Golden Toad and the Harlequin Frog. Pounds, Alan J., Michael P.L. Fogd en and John H. Campbell. 1999. Biological response to climate change on a tropical mountain. 1999. Nature 398: 611 614. Stiles, Gary F., Alexander Skutch and Dana Gardner. 1989. A Guide to the Birds of Costa Rica Cornell, NY. Walther, Glen Reto, Eric Post Peter Convey, Annette Menzei, Camille Parmesan, Trevor J.C. Beebee, Jean Marc Fromentin, Ove Hoegh Guldberg and Franz Bairlein. 2002. Ecological Responses to Recent Climate Change. Nature 416: 389 395.

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TABLES AND FIGURES Table 1. Twenty eight bird species that changed in abundance or distribution + denotes an upslope denotes downslope movement that is predicted to occur during the non breeding Zone 2 Zone 3 Zone 4 Bird Species Fogden Donnelly Palm Fogden Donnelly Palm Fogden Donnelly Palm American Swallow tailed Kite F C C C C Gray headed Chachalaca + F (20) Black Guan R F (12) F U U (4) F C F (12) Black breasted Wood Quail + F R F (17) F F C (37) F F C (26) Red billed Pigeon +* C C F (13) C F (8) C White tipped Dove +* C C F (13) F U (5) F Chiriqui Quail Dove +* F C U (7) R C U (5) F Grooved billed Ani C C U (9) F Green Violetear + C U (8) C C (23) F U (3) Steely vented Hummingbird C F U (7) R F Rufous tailed Hummingbird F F U (6) F Resplendent Quetzal C C C C C C Keel billed Toucan + C F C (25) R F F (16) Three wattled Bellbird C C C C C C Tropical Kingbird + C C C (35) F U (6) Sulphur bellied Flycatcher C C F Dusky capped Flycatcher C C F (14) F F U (5) U Rufous and white Wren + F F C (35) C F (8) Tennessee Warbler + C C C (51) U F (17) F Gray crowned Yellowthroat + C C C (23) F U (9) U Slate throated Redstart + U F (18) C F C (45) F F (10) Golden crowned Warbler +* C C C (46) U C C (25) F U (2) Great tailed Grackle F C C (33) F F Yellow throated Euphonia C C F (18) U F U (4) U Blue gray Tanager +* F F F (11) U U (5) U Red crowned Ant Tanager + U (5) Common Bush Tanager C C (103) C C C (91) White eared Ground Sparrow +* C C C (52) F U (3)

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Appendix A. Bird species observed and their abundances. Unshaded study. data. (D) ZONE S Bird Species 2 2 2 3 3 3 4 4 4 Highland Tinnamou F U U ( 3 ) F C U ( 2 ) Cattle Egret (D) C C U C Turkey Vulture C C C (28) F C F ( 19 ) F C U ( 5 ) Black Vulture C C C (42) U C C ( 27 ) U C U (2) American Swallow tailed Kite (D) F C C C C Sharp shinned Hawk R R (1) R R R ( 1 ) Broad winged Hawk (D) F U (7) F U ( 4 ) F R ( 1 ) Gray headed Chachalaca (F) F (20) Black Guan (F) (D) R F (12) F U U ( 4 ) F C F ( 12 ) Black breasted Wood Quail (F) F R F (17) F F C ( 37 ) F F C ( 26 ) Sunbittern R R R R Band tailed Pigeon C C C F Red billed Pigeon (F) (D) C C F (13) C F ( 18 ) C Ruddy Pigeon F U (2) C F F ( 8 ) C F U ( 3 ) White tipped Dove (D) C C F (13) F U ( 5 ) F Buff fronted Quail Dove U F F C Chiriqui Quail Dove (F) (D) F C U (7) R C U ( 5 ) F Crimson fronted Parakeet R U (47) R R Orange chinned Parakeet R U (43) Brown hooded Parrot F F (21) C C ( 34 ) C F ( 14 ) White fronted Parrot F C (65) Squirrel Cuckoo F F (14) F U ( 4 ) Groove billed Ani (D) C C F (9) F White collared Swift C F F (12) C F F ( 18 ) C F F ( 13 ) C F (14) C C Green Hermit F C C F ( 9 ) C C F ( 18 ) Green fronted Lancebill U U ( 5 ) U Violet Sabrewing C F F (10) C C F ( 18 ) C C F ( 10 ) Green Violetear (F) (D) C F (8) C C ( 23 ) F U ( 3 ) Fork tailed Emerald C C U (3) Fiery throated Hummingbird R F F ( 15 ) Steely vented Hummingbird (D) C F U (7) R F Rufous tailed Hummingbird (D) F F U (6) F Stripe tailed Hummingbird F F (9) C F ( 15 ) C C F ( 12 ) Coppery headed Hummingbird F U (7) C F ( 12 ) C U ( 2 ) Purple throated Mountaingem F U (3) C C ( 33 ) C C F ( 24 ) Green crowned Brilliant C F ( 13 ) C C F ( 11 ) Plain capped Starthroat U U (4) Magenta throated Woodstar (F) F C U ( 6 ) Ruby throated Hummingbird U U ( 2 ) R Resplendant Quetzal (F) (D) C C C C C C

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Orange bellied Trogon C F ( 8 ) C U ( 6 ) C U ( 3 ) Blue crowned Motmot C C F ( 16 ) F C F ( 9 ) F Prong billed Barbet C F F ( 16 ) C C F ( 19 ) Emerald Toucanet C C C ( 21 ) C C C ( 28 ) C C F ( 10 ) Keel billed Toucan (F) C F C ( 25 ) R F F ( 16 ) Hairy Woodpecker R F U F C C U ( 2 ) Golden olive Woodpecker F U ( 5 ) F F ( 9 ) Pale bellied Woodpecker R U ( 5 ) Ruddy Woodcreeper U U ( 6 ) R Olivaceous Woodcreeper C C U ( 5 ) C C F ( 14 ) Spotted Woodcreeper C U ( 2 ) C R ( 1 ) Streak headed Woodcreeper F F U ( 2 ) Red faced Spinetail C U ( 7 ) C U ( 5 ) Spotted Barbtail C C ( 37 ) C C ( 44 ) Ruddy Treerunner F F C ( 33 ) Buffy Tuftedcheek U U ( 4 ) Lineated Foliagegleaner F F U ( 3 ) F F U ( 3 ) Streak breasted Treehunter C F U ( 2 ) Tawny throated Leaftosser U R ( 1 ) Plain Antvireo F C U ( 3 ) Slaty Antwren U C F ( 8 ) Scaled Antpitta R R R ( 1 ) R Silvery fronted Tapaculo C C C ( 23 ) C C C ( 35 ) Masked Tityra F F F ( 9 ) U F Three wattled Bellbird (D) C C C C C C Long tailed Manakin C C C ( 31 ) F Eastern Kingbird U R ( 1 ) U R Tropical Kingbird C C C ( 35 ) F U ( 6 ) Boat billed Flycatcher C F U ( 6 ) U Bright rumped Attila F F F F F F Sulphur bellied Flycatcher (D) C C F Golden bellied Flycatcher F F F Social Flycatcher C C F ( 18 ) Great Kiskadee F F F ( 16 ) Rufous Mourner R R ( 1 ) U R ( 1 ) Dusky capped Flycatcher (F) C C F ( 14 ) F F U ( 5 ) U Western Wood Pewee F F R ( 1 ) F U Yellow bellied Flycatcher F R ( 1 ) R Yellowish Flycatcher F U ( 6 ) C F ( 10 ) C F F ( 11 ) White throated Spadebill (F) (D) C F C C U ( 7 ) C F ( 16 ) Eye ringed Flatbill F F U ( 3 ) F U ( 2 ) Common tody Flycatcher U U ( 2 ) Yellow bellied Elaenia F F ( 11 ) R Mountain Elaenia C C ( 43 ) C C ( 41 ) C F ( 13 ) Mistletoe Tyrranulet C U ( 6 ) C U ( 4 ) C U ( 5 ) Olive striped Flycatcher R C U ( 7 ) C F ( 10 ) Northern Rought winged Swallow F F U ( 6 ) R R Blue and white Swallow C C F ( 14 ) F C F C White throated Magpie Jay R F ( 9 ) Brown Jay C C C ( 63 ) C C F ( 14 ) Plain Wren C C C ( 51 )

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Rufous and white Wren (F) F F C ( 35 ) C F ( 8 ) Rufous breasted Wren R U ( 3 ) House Wren C C F ( 15 ) C C F ( 8 ) U Ochraceous Wren C C ( 27 ) C F ( 16 ) White breasted Wood Wren F F ( 10 ) Gray breasted Wood Wren U ( 2 ) C C C ( 44 ) C C C ( 51 ) White throated Robin F F ( 15 ) C C F ( 19 ) C Clay colored Robin C C C ( 23 ) C C C ( 24 ) Mountain Robin F F C C C ( 40 ) C C F ( 16 ) Black faced Solitaire U C U C ( 24 ) C C C (3 ) Wood Thrush U R ( 1 ) R C C C ( 43 ) C C U F Black headed Nightingale Thrush C U ( 4 ) U U R ( 1 ) Slaty backed Nightingale Thrush C C C ( 25 ) C C C ( 23 ) Ruddy capped Nightingale Thrush U F R ( 1 ) F F F ( 14 ) Orange billed Nightingale Thrush C C C ( 23 ) F Black and yellow Silky Flycatcher F F F ( 15 ) Rufous browed Peppershrike F F ( 15 ) F Yellow throated Vireo U F ( 9 ) R Solitary Vireo R R ( 1 ) R Red eyed Vireo F U ( 4 ) F Philadelphia Vireo F U ( 5 ) R Brown capped Vireo C U ( 3 ) C F ( 8 ) Lesser Greenlet C U ( 5 ) F Bananaquit F U ( 4 ) F F ( 19 ) Black and white Warbler F C ( 22 ) F F ( 12 ) F U ( 3 ) Worm eating Warbler C U ( 7 ) R Golden winged Warbler F F U ( 5 ) F C ( 33 ) U U ( 4 ) Tennessee Warbler C C C ( 51 ) U F ( 17 ) F ( 19 ) U U ( 2 ) U R ( 1 ) Black throated Green Warbler C F ( 13 ) C C ( 25 ) U U ( 7 ) Cerulean Warbler R R ( 1 ) R Blackburnian Warbler (F) F U ( 3 ) F U Chestnut sided Warbler R ( 1 ) Ovenbird (F) F F ( 11 ) F U Northern Waterthrush U R R R ( 1 ) Kentucky Warbler F U ( 2 ) Mourning Warbler R R R ( 1 ) Gray crowned Yellowthroat (F)(D) C C C ( 23 ) F F ( 9 ) U C C ( 75 ) C C ( 22 ) U F ( 8 ) Canada Warbler U R ( 1 ) R Slate throated Redstart (F) U F ( 18 ) C F C ( 45 ) F F ( 10 ) Collared Redstart C F C ( 59 ) Three striped Warbler C C ( 43 ) C C C ( 38 ) Golden crowned Warbler (F) C C C ( 46 ) U C C ( 25 ) F U ( 2 ) Rufous capped Warbler F F C ( 22 ) F U ( 4 ) Zeledonia C F F ( 9 ) Bronzed Cowbird F F R U Great tailed Grackle (D) F C C ( 33 ) F F Northern Oriole F C ( 29 ) U R ( 1 ) Eastern Meadowlark F U ( 5 ) Golden browned Chlorophonia C U ( 4 ) C F F ( 14 ) C U ( 2 )

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Yellow crowned Euphonia R U U ( 4 ) R Yellow throated Euphonia (D) C C F ( 18 ) U F U ( 4 ) U Silver throated Tanager C C U ( 7 ) C Spangle cheeked Tanager U C ( 24 ) F F ( 13 ) Red legged Honeycreeper U F ( 9 ) Scarlet thighed Dacnis U U ( 5 ) C F ( 9 ) U U ( 2 ) Blue gray Tanager (F) (D) F F F ( 11 ) U U ( 5 ) U Summer Tanager F F ( 10 ) U F ( 8 ) Hepatic Tanager F U ( 2 ) F R ( 1 ) F Red crowned Ant Tanager (F) U ( 5 ) Common Bush Tanager (D) C C ( 103 ) C C C ( 91 ) Sooty capped Bush Tanager F C C ( 28 ) Buff throated Saltator F U ( 4 ) Grayish Saltator U F F Black thighed Grosbeak F F F Rose breasted Grosbeak U U ( 4 ) R R ( 1 ) Yellow faced Grassquit C C C ( 48 ) C C F ( 19 ) U F F ( 12 ) Slaty Flowerpiercer R F F C F ( 13 ) Yellow thighed Finch F C ( 30 ) Yellow throated Brush Finch F F U ( 5 ) F F U ( 5 ) F R ( 1 ) Chestnut capped Brush Finch F F C F ( 16 ) F C F ( 11 ) Sooty faced Finch R U U ( 2 ) White eared Ground Sparrow (F) C C C ( 52 ) F U ( 3 ) Rufous collared Sparrow C C C ( 33 ) F C F ( 10 ) F F F ( 13 ) Total Number of Individuals 1689 1306 935 Species Richness 134 56 114 127 66 89 84 58 65


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Marlene
245
Patterns of Seasonal and Altitudinal Change in Monteverde Bird Communities
260
c 2003-12
500
Digitized by MVI
3 520
Previous studies in Monteverde, Costa Rica, have shown that numerous bird species are moving upslope in response
to climate change. While there are an increasing number of such studies that address climate change, most fail to
incorporate seasonal climatic variation. I censused the birds in three elevational zones in the Monteverde area not
only to assess these distributional shifts, but also to determine the effects of season on bird communities. Compared
to Michael Fogdens data from 1979-1992, I found a number of species that have moved into higher zones where
they were previously less common or absent. However, the results showed less upslope movement than those found
by Donnelly (1998), during the dry season, likely due to downslope migrations during the non-breeding season. My
findings suggest that not only are birds continuing to move up in elevation, but also that the effects of global
warming on such movements in birds are less pronounced during the wet season than in the dry season. Also, this
study indicates that future studies of species responses to climate change must account for seasonal variation.
Marlene
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Text in English.
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Birds--Behavior
Climatic changes--Environmental aspects
Costa Rica--Puntarenas--Monteverde Zone--Monteverde
4
Aves--Comportamiento
Cambios climticos--Aspectos ambientales
Costa Rica--Puntarenas--Zona de Monteverde--Monteverde
653
Tropical Ecology Fall 2003
Ecologa Tropical Otoo 2003
655
Reports
720
MVI
773
t Monteverde Institute : Tropical Ecology
856
u http://digital.lib.usf.edu/?m39.417