B ehavioral changes of the Slate throated Redstart Myioborus miniatus and the Collared Redstart Myioborus toquatus along an altitudinal g radient in the Monteverde Cloud Forest Preserve Emma Gabrielsson Department of Biological Sciences, The George Was hington University Abstract Climate change has been found to affect the distribution of bird species in Monteverde, Costa Rica Holmes 2000. In this study, the Slate throated Redstart Myioborus miniatus and the Collared Redstart Myioborus toquatus were observed in the Monteverde Cloud Forest Preserve. Both altitudinal distribution and behavior were observed for both species. It was found that the Slate throated Redstart has moved up in altitude. Further, observations for both species were compar ed using a chi square test, and there were significant differences between the two species, and also within the same species. This study shows that climate change is possibly responsible for the migration up hill, which in turn may impact the future behav ior of bird species, competition and may cause extinction. Resumen El cambio climÃ¡tico ha sido un factor que ha influido en el cambio en la distribuciÃ³n de la especie de aves en Monteverde, Costa Rica Holmes 2000. En este estudio, la especie de reinita Myoborus miniatus y Myoborus toquatus fueron observados en la Reserva del Bosque Nuboso de Monteverde. Observe la distribuciÃ³n de altitudinal y el comportamiento para ambas especie. EncontrÃ© que Myoborus miniatus ha incrementado su distribuciÃ³n altitudina l. A un mas, las observaciones para ambas especie fueron comparadas utilizando una prueba de Chi cuadrado encontrÃ© la diferencia significativas entre la dos especie, y tambiÃ©n dentro de la misma especie. Este estudio muestra que el cambio climÃ¡tico es pos iblemente responsable de la migraciÃ³n cuesta arriba de Myoborus miniatus cambio en esto puede causaron la conducta futura del las especies de aves, la competencia y la extinciÃ³n posible. Introduction There is natural variation in abiotic factors such as altitude that impact the abundance of species. As altitude increases, avian species diversity declines Tramer 1974. There is also a difference in abundance and amount of species in the tropics when compared to temperate areas. When compared to the temper ate zone, the bird species communities in the tropics are complex and many variable components influence composition and abundance Loiselle et al 1992. These variable components can be such things as habitat, altitude, and population variation , all of wh ich could also be affected by many factors Loiselle et al 1992 . Such factors could be deforestation and global climate change . It has been found that human impacts including deforestation have resulted in speci es loss Kessler et al 2001. Global climat e change has already been found to affect distribution in range, loss of amount of species, and the changing of ecosystems McCarty 2001. A s birdsÂ€ altitudinal ranges increase due to climate change they may be taking over habitats of other birds possibly causing competition and eventually possible extinction. This is of immediate concern in tropical montane areas , such as Monteverde , Costa Rica, where the affects of climate change is felt the hardest Holmes 2000.
Unfortunately, Monteverde has already f elt the affects of climate change. There have been studies that show correlation between climate change and extinction of certain frog species in the Monteverde area Pounds 1999 . Additionally, other species have also been affected by climate change . On e ex ample is the Keel billed Toucan which non migrates up to altitudes where the Resplendent Quetzal is found Holmes 2000. Now both of these species are found to be competing for the same food resources. This is thought to be a direct result of global w arming Holmes 2000. Other birds may also be moving up in elevation because of climate changes. Two species of birds that are found in the Monteverde area are the Slate throated Redstart and the Collared Redstart. Interestingly, these two species, even t hough similar in behavior and prey preference , are found at different altitudes. The Slate throated Redstart is found at lower alti tudes usually below 1,600 m , and the Collared Redstart is usually found above 1,600 m . The purpose of this study was to o bserve both the Slate throated Redstart and the Collared Redstart in their natural habitat in the Monteverde Cloud Forest Preserve. I studied these species because in previous studies there have been no observations of altitudinal migration Mahan 1998, F ogden 1993. Furthermore, I also wanted to observe behavior for each species to see if their behavior changes with an increase or decrease in altitude. If the Slate throated Redstart was found at higher altitudes this may be due to affects of climate chan ge. Furthermore, it will be interesting to note behavior of these species, and if these behavioral observations differ at different altitudes. If so, these behavioral changes could possibly be the affects of habitat change, and they could affect foraging , and com petition for prey or ultimately survival of the species. Materials and Methods Description of habitat and study species : The Monteverde Cloud Forest Preserve is divided into 6 different Holdridge life zones. Holdridge life zones are based on pr ecipitation, altitude, and biotemperature. The two zones of interest in this study are zone 3, ranging from about 1,500 Â 1,600 m but sometimes lower, and zone 4, ranging from 1,600 m and above Fogden 1993 . At about 1,500 m the forest is dense with tall trees. Some common tree species found here are Psychotria jimenezii in the Rubiaceae family as well as Ardisia compressa in the Myrsinaceae family Haber et al 2000 . At higher elevations increasing towards the timber line, there are strong winds and the tree species are much more exposed. Common tree species found here are Elaeagia auriculata in the Rubiaceae family and Clusia spp . in the family Clusiaceae Haber et al 2000 . T he Slate throated Redstart Myioborus miniatus and the Collared Redstart M yioborus toquatus are common in zones 3 and zones 4 of the MCFP. These insectivorous birds are both approximately 12 cm long, weighing about 10 g. They are in the genus Myioborus , which is known to use unique animated behavior, as well as flashing or flu shing of their tail feathers in order to pursue prey which are usually homopterans Galatowitsch and Mumme 2004. T he Slate throated is known to occupy zo ne 3 , and the Collared Redstart has historically been found in zone 4 and at times in zone 3 Fogden 1 993. Study Site I conducted in the Monteverde Cloud Forest Preserve, for 17 days from October 21, 2006 Â November 15, 2006. The trails walked included: Bosque Nuboso, El Camino, Wilford
Guindon, El Roble, Chomogo, Pantanoso, and La Ventana Figure 1 . The se trails were walked in the early morning from approximately 6:30am to 12pm each day of data collection. Methods Each day I choose a different starting point for data collection, in order to survey as much area of the preserve as possible. I alternated randomly between the Camino, Nuboso or Wilford Guindon trails . When a trail was chosen, the calls and sounds of the Slate Throated Redstart were played continuously for 5 minutes, while walking, looking, and actively listening for this species . This was th en followed by 5 minutes of silence . In the following 5 minutes the calls and sounds of the Collared Redstart were played . These calls and sounds were played on a Panasonic mini cassette player model number RQ L3G . A bird of either species could be obse rved anytime during these 15 minute periods which were then repeated continuously while in the MCFP. If a bird was found, a stop watch was activated. At every 30 second interval, the exact b ehavior a t that time was noted. The activities that were observ ed included: chasing, flashing, sitting, flying, fidgeting, and hopping . See Table 1 for a description of each. The observation time depended upon the activity of the bird, and how difficult it was to observe. These birds were difficult to observe when at a far distance, or they were moving too quickly. When a bird could no longer be seen, the observation was finished. At this time, the altitude and time of observation were recorded. The trails were walked at a pace of about 12 14 meters per minute , with 2 3 hours required to walk one trail. Total observation time was affected by how many birds were found, how long the species could be observed and the weather conditions during extremely sunny and rainy days almost no birds were observed . A fter assessing the data it was decided that altitudes above 1580 m would be considered zone 4 and altitudes below 1580 m would be considered zone 3. Both new altitude markers and FogdenÂ€s method of separating the reserve into these zones according to vegetation were cons idered while making this decision Fogden 1993. Finally a Chi Square test was used to assess all comparisons. I used this test because I was constantly only comparing two factors Results I observed a total of 87 birds during this study . T he Slate throat ed Redstart S.T. and the Collared Redstart C.R. were present in both zones 3 and zones 4. Thirty S.T. were found in zone 3 , and 18 were found in zone 4. Nine C.R. were found in zone 3 and 30 were found in zone 4 Table 2 . S.T. were found chasing, an d flashing more frequently than C.R. in zone 4 Chi Square test, X 2 >3.84, p < .05 Table 3. C.R. were found sitting and chirping more frequently than S.T. in zone 4 Chi Square test, X 2 >3.84, p < .05 Table 3. A ctivities that were not significantly d ifferent include: flying, fidgeting, and hopping Table 3. B etween the two species when in zone 3 , S.T. were found chasing, flashing, hopping and flying more frequently than C.R. in zone 3 Chi Square test, X 2 >3.84, p < .05. B ehavior that was not signi ficant include sitting, chirping and fidgeting , meaning that there was no noted change in behavior between these two species Table 3 . Behavior was also compared between the same species in different zones. T he S.R. were found fidgeting more in zone 4 th an in zone 3 , while all other behaviors were not different from each other Chi Square test, X 2 >3.84, p < .05 Table 4 . Additionally, the C.R. behaviors of flashing, sitting, chirping, fidgeting and hopping were all were observed more in zone 4 than in zone 3, while all o ther behaviors were not Chi Square test, X 2 > 3.84, p < .05 Table 5 . Lastly, activity budgets between the Collared Redstart and Slate throated Redstart were also made by comparing average activity for each species in each zone Figu re 2 .
Discussion I t was interesting to find that some Slate throated Redstarts S.T. were indeed found in zone 4, where in past years they had never been seen before Fogden 1993 . This elevational migration could bring competition with the Collared Re dstart C.R. as well as other zone 4 species. Another implication of this movement uphill may be the future development of interspecific aggression between the S.T. and the C.R. which has been found in other species in the Amazonian rainforest Robinson a nd Terborgh 1995 . Also, these birds are not likely altitudinal migrants Loiselle et al 1992. This further supports the hypothesis that S.T. are moving up in altitude possibly because of the affects of global warming . These two species may begin to comp ete with each other for prey, which may in turn cause the amount of prey available to decline. Lastly, I also observed the C.R. in zone 3, where they have been found vagrantly in past studies Mahan 1998, Fogden 1993. To study behavior in each species r elative to its life zone , I compared all behaviors between the S.T. and the C.R. in both zone 3 and zone 4 . Overall I observed more S.T. than C.R. in zone 3. I observed that the S.T. flashed its tail far more frequently than the C.R. in both zones. This flashing is usually to flush insects out of the trees, or out of their tail if caught in the pursuit Galatowitsch and Mumme 2004. I also noticed that the S.T. would chase insects or other S.T. that were in pursuit of insects more than C.R. This is import ant because these two species are known to have the same prey. So if the S.T. is found actively foraging more , when compared to the C.R., this may cause a reduction in food resources thus future competition for prey between these two species . Also i n zone 3, the S.T. seemed to be more active in flying and hopping behaviors , when compared to the C.R. This is important because this type of animated behavior is also used to catch prey Galatowitsch and Mumme 2004 . In zone 4 there was a unique difference in behavior between the C.R. and S.T. T he C.R. behavior was found sitting and chirping more than the S.T. and therefore calmer i n zone 4 . This may be because the C.R. is commonly found at higher elevations and is adapted for these lower temperatures Stiles 1989 . This may also show that compared to the S.T., the C.R. is a more passive bird at higher elevations. Comparisons between the same species in different zones were then assessed. The only observed behavior that was significantly different for the S.T . between z one 3 and zone 4 was fidgeting. I nstead of hopping or chasing insects , these S.T. would fidget and seem overall more anxious in zone 4 when compared to zone 3 birds. This was interesting to note, since they a re not commonly found in zone 4. T his behavior may be their way of adjusting to a new altitude and habitat type. C.R. behavior also differed from zone 3 to zone 4. I noticed that as altitude increased , the C.R. seemed to be acting more calmly. This species would sit still longer , and would respond to playback more often . This behavior may mean that these birds are more passive because they did not evolve with high levels of competition, compared to the S.T. which displays more active behavior because of the possibility that it did evolve wit h competition. Additionally, migrant birds are usually found in lower elevations of the MCFP, so this supports that possibly the S.T. does deal with more competition than the C.R. Terborgh 1989. T his behavior could affect the foraging success of the C.R . because the S.T. has moved up in altitude causing there to b e a new introduced competitor. Further, since both species are part of the genus Myioborus , which are explicitly known to use their different colored plumage and active behavior to startle prey in order to capture them , this calm behavior may have to change in order to possibly compete with the S.T. Galatowitsch and Mumme 2004.
T his study has shown that the Slate throated Redstart has migrated into higher areas. Although this di fference is o nly about 10 m , this difference is significant because now this species is found in a different zone type and ultimately a new habitat . This migration may eventually cause competition between other species historically found at higher elevations. Also, be havior of both species differs depending on the zones and species present . This study further emphasizes how all types of species are being affected by global warming, and that action must be taken in order preserve species and habitats that are being lost . Future study should include a larger sample of both species in each zone, with a greater emphasis on zone 4 areas, and behavior shown by birds in that zone . Further, a longer study time will allow for a greater data set to be analyzed, and will help to e mphasize these results. Additionally, the separation between zone 3 and zone 4 areas of the reserve should be made more definite. Finally, it would be interesting to conduct this study in the dry season to see if the behavior of the birds changes. Acknowledgements I would like to thank the Monteverde Cloud Forest Preserve for allowing me to use the amazing trail system, and the guides that helped me find the best areas of the reserve to observe my species. Thank you Tania Chavarria Pizzaro for h elping me understand my findings , and helping me through everything, and thank you Alan and Karen Masters for being wonderful professors and helping me all along the way this semester and with this project. I would like to thank my tico family for giving me breakfast everyday so early so I was possible to arrive at the preserve at a decent hour. Lastly, I would like to thank my classmates , Cam and Tom for making this semester abroad the most amazing time ever, one that I will never forget. Pura Vida. Lit erature Cited : Fogden, M . 1993. Wood Warblers. An Annotated Checklist of the Birds of Monteverde and Penas Blancas. Published by Michael Fogden. Monteverde, Costa Rica , 54 55. Galatowitsch, M. L. and R. L. Mumme. 2004. Escape Behavior of Neotropical Homopt erans in Response to a Flush Pur suit Predator. Biotropica 36: 586 595. Haber, W.A., W. Zuchowski, and E. Bello. 2000. An Introduction to Cloud Forest Trees: Monteverde, Costa Rica . Mountain Gem Publications: Monteverde, Costa Rica, 11 13, Holmes, B . 2000 . Case of the dwindling cloud fores t. International Wildlife 30: 20. Kessler, M., S. K. Herzog, J. F. and K. Bach. 2001. Species richness and endemism of plant and bird communities along two gradients of elevation, humidity and land use in the Bolivian An des. Diversity and Distributions 7: 61 77 . Loiselle, B. A. and J. G. Blake. 1992. Population Variation in a Tropical Bird Community . BioScience 42: 838 845. Mahan, J. S. Â‚Altitudinal Abundance of Collared Redstarts and Slate Throated Redstarts in the Monte verde Cloud Forest PreserveÂƒ in Tropical Ecology and Conservation : Fall 1998, CIEE, Monteverde, Costa Rica. McCarty, J. P. 2001. Ecological Consequences of Recent Climate Change. Conservation Biology 15: 320 333. Pounds, J.A., M.P.L. Fogden, and J.H Campbe ll. 1999. Biological response to climate change on a tropical mountain. Nature 398: 611 615. Powell, George V.N. 1979. Structure and Dynamics of Interspecific Flocks in a Neotropical Mid Elevation Forest. The Auk 96: pp 375 390. Robinson, S. K. and J. Terb orgh. 1995. Interspecific Aggression and Habitat Selection by Amazonian Birds. The Journal of Animal Ecology 64: 1 11.
Sanatana Castellon, E . 2000. Dynamics of understory birds along a cloud forest successional gradient. The University of Wisconsin Madiso n; Dissertation : AAT 9972863 Stiles, F.G. and A.F. Skutch. 1989. A Guide to the Birds of Costa Rica. Cornell University Press, Ithaca, New York : 382, 401 402. Terborgh, J. 1989. Where Have All the Birds Gone? Essays on the Biology and Conservation of Bir ds that Migrate to the American Tropics . Princeton University Press, New Jersey: 149 155. Tramer, E. J. 1974. On Latitudinal Gradients in Av ian Diversity. The Condor 76: 123 130.
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Cambios en el comportamiento de la reinita (Myioborus miniatus) y la reinita (Myioborus toquatus) a lo largo de un gradiente altitudinal en la Reserva de Monteverde
Behavioral changes of the Slate-throated Redstart (Myioborus miniatus) and the Collared Redstart (Myioborus toquatus) along an altitudinal gradient in the Monteverde Cloud Forest Preserve
Climate change has been found to affect the distribution of bird species in Monteverde, Costa Rica (Holmes 2000). In this study, the Slate-throated Redstart (Myioborus miniatus) and the Collared Redstart (Myioborus toquatus) were observed in the Monteverde Cloud Forest Preserve. Both altitudinal distribution and behavior were observed for both species. It was found that the Slate-throated Redstart has moved up in altitude. Further, observations for both species were compared using a chi square test, and there were significant differences between the two species, and also within the same species. This study shows that climate change is possibly responsible for the migration up hill, which in turn may impact the future behavior of bird species, competition and may cause extinction.
Se ha encontrado que el cambio climtico afecta la distribucin de las especies de aves en Monteverde, Costa Rica (Holmes 2000). En este estudio, la especie de reinita Myoborus miniatus y Myoborus toquatus fueron observados en la Reserva del Bosque Nuboso de Monteverde.
Text in English.
Birds--Behavior--Costa Rica--Puntarenas--Monteverde Zone
Aves--Comportamiento--Costa Rica--Puntarenas--Zona de Monteverde
Tropical Ecology 2006
Ecologa Tropical 2006
t Monteverde Institute : Tropical Ecology