FOLLOWING DARWIN S FINCHES IN THE GALAPAGOS

Transcription

1 FOLLOWING DARWIN S FINCHES IN THE GALAPAGOS 2015 FIELD REPORT Amazon Riverboat Exploration 2012 FIELD REPORT 1

2 Following Darwin s Finches in the Galapagos 2015 FIELD REPORT Background Information LEAD PI: Luis Fernando De Leon REPORT COMPLETED BY: Luis Fernando De Leon PERIOD COVERED BY THIS REPORT: December 2015 March 2015

3 Phone: Web: earthwatch.org facebook.com/earthwatch twitter.com/earthwatch_org Dear Earthwatch volunteers, We have come to the end of our 2015 field season. This was a very productive field season for our project Following Darwin s finches in the Galapagos. We set out to advance our knowledge about the ways in which humans may interact with Darwin s finches, and how these interactions might influence the evolutionary processes determining the radiation of Darwin s finches in the Galapagos. During this field season, we were able to confirm our previous observations that the natural diet of Darwin s finches is being influenced by the introduction of novel human food items. We also observed that a large number of finches might be becoming dependent on these human foods. These observations highlight the importance of our work and are a key inspiration for continuing with our project. The most novel and exciting element of our 2015 field season was the inclusion of controlled field experiments. These experiments very clearly demonstrated that finches in humanimpacted areas display different foraging behaviors, are bolder, and strongly prefer human foods over their natural foods. Our results suggest that finches have undergone significant behavioural and dietary shifts in areas where they co-occur with humans. Results from of our project will be delivered to both the Galapagos National Park Authorities and the Charles Darwin Foundation in the form of publications, public talks, and advice, which we hope will support their conservation efforts in the Galapagos. Of course, we would not have been able to collect the data supporting these observations without the help of our dedicated Earthwatch volunteers. We are very happy to have had the opportunity to share our field season with three dynamic and generous groups of people. You were willing to withstand the Galapagos sun and the rather strenuous walks through rough lava terrain to get that last piece of data for our project. This experience not only enriched our project but also our field experience and the way we think about science. We really appreciate your interest and support of our project and we hope you also had a great experience in the field. Sincerely, Luis Fernando De Leon

4 SECTION ONE: Scientific research achievements TOP HIGHLIGHT FROM THE PAST SEASON Our Galápagos 2015 expedition confirmed and substantially extended our key finding from previous years: that the natural diet of Darwin's finches is being influenced by the introduction of novel human food items. The most novel and exciting element of our 2015 field season was the inclusion of controlled field experiments. These experiments very clearly demonstrated that finches in human-impacted areas display different foraging behaviours, are bolder, and strongly prefer human foods over their natural foods. Our results suggest that finches have undergone significant behavioural and dietary shifts in areas where they co-occur with humans. REPORTING AGAINST RESEARCH OBJECTIVES Our specific objectives were as follows: Objective 1: To determine the morphological distribution (beak size and body size) of Darwin's ground finches (Geospiza fortis, G. magnirostris, G. fuliginosa, and G. scandens) at disturbed and undisturbed sites on Santa Cruz Island. We used mist-nets to collect birds from the two different sites on Santa Cruz Island (El Garrapatero and Academy Bay). From each bird we collected the following morphological measurements: beak size dimensions (length, depth and width), head dimensions (length, depth and width and depth), and body dimensions (tarsus, wing span and mass). We also photographed each bird in order to perform geometric morphometric analyses of beak size variation within and among species. During our 2015 field season we were able to sample approximately 200 birds including Geospiza fortis G. Magnirostris, G. Fuliginosa, and G. Scandens (Table 1). These new individuals have been added to our long-term database which will help us to explore broad patterns of spatial and temporal variation in the morphological distributions of each species (Fig. 1)

5 Table 1. Total samples per species collected during our 2015 field expedition. Species Common name Number of individuals Sex Geospiza magnirostris Large ground finch 2 M & F Geospiza scandens Cactus finch 22 M & F Geospiza fuliginosa Small ground finch 54 M & F Geospiza fortis Medium ground finch 74 M & F Platyspiza crassirostris Vegerarin finch 35 M & F Camarhynchus parvulus Small tree finch 16 M & F TOTAL 203 Objective 2: To quantify morphological differences among Darwin's ground finches within and between sites. We used the above morphological measurements to explore morphological differences among the most common Darwin's finches from Santa Cruz Island (results to appear in upcoming publication). Objective 3: To estimate population density and abundance of each of the Darwin's ground finches at each site on each island. Our mist-netting data from 2015 will allow us to estimate capture per unit effort (CPUE) and bird density at each of our sampling sites. We are in the process of transcribing field notes to start formal analysis of the data. Objective 4: To quantify feeding preferences and use of feeding resources in disturbed and undisturbed sites at each site. We here are particularly interested in the proportion of human food items present in the diet of the different ground finches species at each site. We addressed this objective using a combination of feeding observations and feeding experiments. Feeding observations Using binoculars, we recorded food consumption while finches were engaged in normal feeding behaviour. This was done by following both banded and unbanded birds during random walks within both the disturbed and undisturbed sites on Santa Cruz Island. With the help of the Earthwatch volunteers we were able to collect over 2000 feeding observations of finches eating human food items. These data have been tabulated, and we are currently compiling them with data from Feeding experiments We were also able to develop feeding experiments to test for finch preference for human vs. natural food resource, assessing these preferences in both disturbed and undisturbed environments on the island.

6 Objective 5: To estimate the distribution of the feeding resources in disturbed and undisturbed sites on each of the human populated island. During our 2015 field expedition we did not quantify the distribution of food resources for finches. We will therefore rely on data collected from previous years for this part of the project. Objective 6: To quantify the levels of genetic variation, gene flow and hybridization among Darwin's ground finches within each study site on each island. For each of the individual bird sampled we were able to extract blood samples for DNA analyses. All of these samples will be in proper storage until funding becomes available for genetic analyses. Changes to research plan or objectives There were two principal changes to our field protocol during our 2015 expedition. First, as mentioned above, we did not quantify the distribution of food resources for finches at our study sites. We felt that we already have enough data on this topic and so it wasn't necessary to repeat these surveys. Second, in 2015 we included feeding experiments to estimate finches' preference for human vs. natural/native foods. We obtained interesting results from these experiments, which were reported against our research objectives (see above).

7 PARTNERSHIPS SECTION TWO: Impacts We continue working in close collaboration with the Galapagos National Park Authorities who provided the necessary permit for our research. Our research also depends on our collaboration with the Charles Darwin Foundation, which provides the logistical support to carry out our field work. Results from of our project will be delivered to both institutions in the form of publications, public talks, and advice, which we hope will support their conservation efforts in the Galapagos. Other international institution such as INDICASAT (Panama), McGill University (Canada) and University of Massachusetts (USA) have continued to support our project and so remain an important component of this partnership. CONTRIBUTIONS TO CONVENTIONS, AGENDAS, POLICIES, MANAGEMENT PLANS During our 2015 field expedition, we had the opportunity to talk, via skype, with students from Canton High School, Massachusetts (USA). During this conversation we were able to discuss with students from three different years about some of the relevant aspects of our research. Local We anticipate that the primary beneficiaries our of research will be local conservation agencies such as the Galapagos National Park the Charles Darwin Foundation. This year, we had the opportunity to interact more closely with several managers from the Galapagos National Park. For example, in mid-january, we hosted a team of Park conservation officers who accompanied us in the field for the day, and were able to observe our field work first-hand and ask questions about our research. We also prepared a onepage, non-technical summary of our field activities in Spanish for the Park Authorities to use in their local education and outreach initiatives. When our data have been analyzed and published, we plan to develop a series of concrete policy measures to share with the Galapagos National Park authorities. For example, our preliminary data from feeding observations and experiments suggest that additional control measures need to be taken in town to further discourage tourists and locals alike from feeding wildlife. DEVELOPING ENVIRONMENTAL LEADERS During our 2015 field expedition, we had the opportunity to converse, via skype, with students from Canton High School, Massachusetts (USA). During this conversation we were able to talk to students from three different years about some of the relevant aspects of our research. The students were also able to ask question about our research as well as general questions about doing science and becoming scientists. For more details please see the following video: CONSERVATION OF TAXA 1) Geospiza spp. (Darwin's ground finches) 2) An iconic example of adaptive radiation in nature. 3) Our project attempts to understand how human disturbances could alter the diversity of Darwin's finches of the Galapagos. This is important because preserving biodiversity also depends preserving the processes that promote and maintain such biodiversity. Our project will therefore generate novel knowledge that could be incorporated into conservation plans and management strategies of Darwin's finches of the Galapagos. This knowledge could also be applicable to other species of the Island.

8 LOCAL COMMUNITY ACTIVITIES Our project offered the opportunity to include Ecuadorian student (Sofía Carvajal) to develop her Ph.D. research project in the Galapagos. Sofía is doing her Ph.D. at McGill University and is being co-supervised by Andrew Hendry and Luis Fernando De León. She is expanding in our project to study the interaction between finch predation and plant community in the Galapagos. During the developing of our feeding experiments in town, we had the opportunity to explain our research to members of the public. This was a nice opportunity to talk about the subtle ways in which human might interact with biodiversity. DISSEMINATION OF RESEARCH RESULTS Scientific peer-reviewed publications Gotanda, G., Sharpe, D.M.T. and De León, L.F Galapagos Mockingbird (Mimus parvulus) Preys on an Invasive Mammal. Published in Wilson Journal of Ornithology. 127: De León L.F., Gotanda K., Podos J., Raemaekers, J., Chávez J., Hendry A., and Sharpe D. Human impacts on ecological niches in Darwin's finches. In prep. Grey literature and other dissemination De León, L.F., D. Sharpe, K. Gotanda, S. Carvajal, J. Chaves, J. Raeymaekers, A. Hendry, & J. Podos Exploring human impacts on the evolution of Darwin s finches. Earthwatch Summit, Boston, USA. De León, L.F. Impactos humanos sobre la evolución. Reunión técnica sobre el ecosistema humano: microbiomas y evolución. Centro Nacinal de Salud Pública, Lima, Perú (Invited speaker). December 2014 De León, L.F. Ecology and evolution in Island birds. University of Massachusetts (Invited seminar), Boston, USA. December Other Galapagos Islands Interview: Blog posts: Diana Sharpe: Andrew Hendry: Kiyoko Gotanda: Team 1 at EG: And Team 2: Team 3 Team Pinzones Twitter:

9 PROJECT FUNDING SECTION THREE: Anything else For our 2015 field season, we applied for funding to US National Science Foundation, and National Geographic, but unfortunately we did not succeed. For this reason, Earthwatch and its volunteer program remained our only funding source for our project in ACKNOWLEDGEMENTS Logistical support and permits were provided by the Galapagos National Park Service and the Charles Darwin Foundation. Thank you to all the Earthwatch volunteers for their passion and enthusiasm in the field. APPENDICES 1. Gotanda et al PDF of published manuscript 2. De León et al Poster for Earthwatch summit 2014

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