FIELD REPORT: 2024 TIGER BEETLE MARK-RECAPTURE METHODS (pdf)
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Date: July 13-14, 2024
Location: Explorama’s Napo-Sucusari Biological Reserve, Loreto Peru
Study Site: The Amazon Conservatory for Tropical Studies (ACTS)
Lead Researcher: Dr. David L. Pearson
Team Members: William Flores L., Lucas Kahler, Philip Kahler, Cinda Murray and Matthew Naczi
Please note: The following report is replicated in part with permission from these researchers’ recent article: Pearson, D. L., Flores L., W., Kahler, L., Kahler, P., Murray, C., & Naczi, M. (2024). Useful methods for measuring tiger beetle (Coleoptera: Cicindelidae) populations. CICINDELA, 56(3), 53.
Abstract: We tested several techniques for measuring population size, movements of individuals, and phenology (life cycle) of a tiger beetle species in the genus Odontocheila (probably O. cajennensis femoralis Chaudoir) on a study site in terra firma forest of northeastern Peru. Mark and recapture over two days yielded useful data on population size with the Lincoln-Petersen Index. Captured tiger beetles were also individually marked so that eventually with GPS their movements could be detected. The number of phoretic (transported) mites on each individual could also prove useful for aging and emergence timing between sexes and among species.
Resumen: Probamos varias técnicas para medir el tamaño de la población, los movimientos de los individuos y la fenología (el ciclo vital) de una especie de escarabajo tigre del género Odontocheila (probablemente O. cajennensis femoralis Chaudoir) en un sitio de estudio en el bosque de tierra firme del noreste del Perú. El marcado y la recaptura durante dos días arrojaron datos útiles sobre el tamaño de la población con el índice de Lincoln-Petersen. Los escarabajos tigre capturados también fueron marcados individualmente para que eventualmente se pudieran detectar sus movimientos con GPS. El número de ácaros foréticos (transportados) en cada individuo también podría resultar útil para la determinación de la edad y el momento de aparicion como adulto entre sexos y entre especies.
Introduction
Few studies of tiger beetle populations have investigated much beyond visual census counts along paths or transects (Pearson and Derr 1986, Diogo et al. 1999, Knisley and Haines 2010, Schlesinger et al. 2011, Cornelisse et al. 2013, Knisley et al. 2014). The movement distances and directions of adult individuals within and between habitats and microhabitats is also lacking for all but a few intensively studied endangered species (Gowan and Knisley 2014, Knisley and Gwiazdowski 2021). Our aim was to test a technique of marking and releasing tiger beetles to determine the reliability of re-finding and recapturing individuals on a subsequent day for total population estimates as well as movements of individuals.
We wanted to make this procedure and its analysis as simple as possible so that it could be readily adapted curricula and field interests. Could marked individuals be noted and identified with binoculars, or was recapture necessary? How extensive did the marking need to be without significantly altering their appearance and possibly increasing attraction by predators? How many individuals needed to be marked so that recapture was likely? How long of a transect and how much time was needed to obtain adequate data? What basic equipment was needed to obtain reliable data? Can additional factors such as phoretic mite load measured on captured individuals be used to deduce life cycle timing? Can the resultant population analysis be readily understood and applied to conservation efforts by non-scientists and decision-makers (Ferraz et al. 2021)?
Materials and Methods
On 13 and 14 July 2024 we surveyed several areas around the Amazon Conservatory for Tropical Studies (ACTS) field station and the Napo Sucusari Biological Reserve for forest tiger beetles. This research station is located near Explornapo Lodge on the Sucusari River 160 km northeast of Iquitos, Peru (−3.249, −72.909) (Figure 1). We chose a study area where these tiger beetles were active, and it consisted of a roughly circular path that was 1–2 m wide and 850 m long in primary terra firma (not seasonally flooded) forest (elevation = 90 m). Most participants had little to no previous experience with tiger beetles in the field. Two hours of training to recognize, capture, and mark tiger beetles along this path proved sufficient for reliable data gathering on subsequent days (Figure 2).
tiger beetles along the forest transect path.
From 1430 to 1630 on 15 July, we walked slowly along the selected transect path and caught as many individuals as we could using an aerial insect net (30 cm diameter). A team of three volunteer researchers was most effective. One handling the net capture/marking, one watching the path and spotting tiger beetle movement/flight path, and one to record data (Figure 3). We had permission to conduct this capture and release experiment (ACTS approval #24-108), but we did not have permission to collect and send specimens for identification to taxonomic experts outside Peru. Tentative field identifications were based on previous experience of the first author (Pearson 1985, 1994; Pearson and Anderson 1985; Pearson and Derr 1986; Erwin and Pearson 2008) and recent taxonomic revisions (Moravec 2018, 2020). Some tiger beetle individuals were captured on the ground and others on undergrowth leaves to which they had flown to escape us. The day was warm with shaded sunlight along the entire path (cloud cover: 18–30%: temperature: 29–30°C, wind: light to gentle breeze from the south; humidity: 74%). We marked each tiger beetle on its hard forewings (elytra) with a unique combination of yellow and/or green dots (Figure 4) using Posca extra fine point paint pens (Uni Mitsubishi Pencil, Tokyo, Japan). We recorded the sex of the tiger beetle and number of phoretic (transported) mites (Houck and O’Connor 1991) present on each individual using reversed binoculars as a field microscope (Figure 5). We also noted morphological details for species identifications of the captured tiger beetles with close-up photos.
On 16 July we repeated the capture effort along the same path at the same time of day. The weather was like the previous day. Before capturing each tiger beetle, we observed it through binoculars on the ground or undergrowth leaf to determine if it was marked from the previous day. We then captured it with the net and noted its species, sex, mite load, and rechecked it for color marks. Several of these individuals evaded capture, but the presence or absence of marks was included through the binocular sighting.
We calculated the total population number for this site using the Lincoln-Petersen Index capture-recapture formula N = MT/R, in which N = Total population, M = Total marked, R = Number of marked found on second visit, and T = Total marked and unmarked found on second visit. The assumptions of this formula are:
1) The population is closed with no migration in and out.
2) All members of the population mix randomly (no territoriality).
3) The marks are not lost between sampling periods.
4) The marks do not affect the chances of recapture (predation, investigator bias).
Results
On the first day we captured 9 individuals of a large (length = 14–15 mm) species in the Odontocheila cajennensis (Fabricius) species group (most likely O. c. femoralis Chaudoir) and one individual of the small species (length = 8 mm) Ronhuberia near eurytarsipennis (W. Horn). Each was marked uniquely with either a yellow paint spot or a green spot on the front, middle, or back part of the left or right elytron. On others, two spots, either of the same or different colors were applied to the elytra at different positions and combinations.
On the second day we captured and observed 15 unmarked individuals of O. cajennensis and one of Poecilochila ventralis (Dejean) (length = 10 mm). Two marked individuals of O. cajennensis from the previous day were recaptured. Yellow dots were much more readily seen through binoculars (up to 5 m distance) than were the green dots. To calculate the Lincoln-Petersen Index of population estimate, we used only the data from O. cajennensis.
M = 9, T = 17, R = 2 N = 9 × 17 ÷ 2 = 76.5
In other words, two out of the 17 tiger beetles found on the second day were already marked, which is about 12% of the sample. Thus, if two tiger beetles represented 12% of the population, 100% would be a little over 76.
Fifty two percent of the O. cajennensis captured were males and 47%were females. The number of phoretic mites (Fig. 6) was somewhat greater on females (mean = 10.1, s.d. = 8.2) than males (mean = 8.1, s. d. = 9.4) but with no significant statistical difference (t-test p > 0.05). The specific location of capture of each individual was not measured in this study, but with a GPS unit it could readily have been.
Discussion
With this capture-recapture technique our estimate of the population in this study area was more realistic and useful than a standard census of tiger beetles observed would have been (17 vs. 76.5). It is a relatively simple and quick technique that provides critical information otherwise unavailable or analytically incomplete. For instance, simple census data from similar Peruvian forest sites have shown extreme seasonal changes in tiger beetle abundance (Pearson and Derr 1986), but data from mark and recapture comparing sympatric species and different microhabitats are likely to reveal more substantive and reliable patterns throughout the year.
These types of data would also be important for species considered threatened or endangered. To limit potentially harmful interference, the minimum number of individuals needed to be captured and marked as well as the size of the study area or transect can be readily modified to accommodate the behavior and habitat parameters of the tiger beetle being monitored. If more complex comparisons are needed, the Schnabel Index (Schnabel 1938), which is an extension of the Lincoln– Petersen method to more than two sampling occasions, and Huggins Closed Capture Models, which allows for the inclusion of additional environmental factors (covariates) (Chao and Huggins, 2010), can be used.
The length of time between marking and recapturing is a limitation for this technique. The more days in that interval the more chance for predation and other factors that would reduce the number of marked individuals available for recapture. Cooler temperatures, rain, or other changes in physical factors on the recapture day could also significantly impair chances for recapture and thus the calculation of N. Substituting pitfall traps (containers placed flush with ground level into which for aerial nets to capture and mark the tiger beetles has been used in more open habitats (Herrera‐Russert et al. 2021), but pitfalls have their own set of limitations and biases (Montgomery et al. 2021).
Future studies using a mobile GPS unit to note the specific locality of observation/capture within the study site would make frequency and distance of movements of individually marked tiger beetles possible, even in difficult terrain. Other studies that reinforce the assumption that phoretic mite load is correlated with the age of the individual would be helpful. It could also reveal phenological (life cycle) details such as if one sex or species emerges before the other (Houck and O’Connor 1991).
The equipment needed for effective population studies such as this one includes aerial net, close-focusing binoculars, marking pens with long- lasting and waterproof marks, GPS device, and waterproof booklet for recording data. With this equipment, limited time, few personnel, low funding, and little previous experience, effective assessment of tiger beetle populations anywhere in the world can be realized.
References:
Chao, A., & Huggins, R. M. (2010). Four modern closed-population capture–recapture models. In S. C. Amstrup, T. L. McDonald, & B. F. J. Manly (Eds.), Handbook of capture-recapture analysis (pp. 58–87). Princeton University Press.
Cornelisse, T. M., Bennett, M. K., & Letourneau, D. K. (2013). The implications of habitat management on the population viability of the endangered Ohlone tiger beetle (Cicindela ohlone) metapopulation. PloS One, 8(8), e71005.
Diogo, A. C., Vogler, A. P., Gimenez, A., Gallego, D., & Galian, J. (1999). Conservation genetics of Cicindela deserticoloides, an endangered tiger beetle endemic to southeastern Spain. Journal of Insect Conservation, 3, 117–123.
Erwin, T. L., & Pearson, D. L. (2008). A treatise on the western hemisphere Caraboidea (Coleoptera): Their classification, distributions, and ways of life. Vol II (Carabidae – Nebriiformes 2 – Cicindelitae). Pensoft.
Ferraz, K. M., Micchi de Barros, P., Gonçalves Morato, R., Abreu Bovo, A. A., Ortiz Rocha da Costa, C., Ribeiro, Y. G. G., Cunha de Paula, R., Desbiez, A. L. J., Angelieri, C. S., & Traylor‐Holzer, K. (2021). Bridging the gap between researchers, conservation planners, and decision makers to improve species conservation decision‐making. Conservation Science and Practice, 3, e330.
Gowan, C., & Knisley, C. B. (2014). Distribution, abundance, and conservation of the highly endemic Coral Pink Sand Dunes tiger beetle, Cicindela albissima Rumpp. Biodiversity, 15, 119–129.
Herrera‐Russert, J., López‐López, A., Serrano, J., Cordero‐Rivera, A., & Galián, J. (2021). First population estimates of the vulnerable southeast Iberian endemic tiger beetle Cephalota (Taenidia) deserticoloides. Insect Conservation and Diversity, 14, 793–799.
Houck, M. A., & O’Connor, B. M. (1991). Ecological and evolutionary significance of phoresy in the Astigmata. Annual Review of Entomology, 36, 611–636.
Knisley, C. B., & Gwiazdowski, R. (2021). Conservation strategies for protecting tiger beetles and their habitats in the United States: Studies with listed species (Coleoptera: Carabidae: Cicindelidae). Annals of the Entomological Society of America, 114, 293–301.
Knisley, C. B., & Haines, R. D. (2010). Distribution and conservation status of Omus submetallicus G. Horn and its confusion with Omus californicus lecontei G. Horn (Coleoptera: Carabidae). The Coleopterists Bulletin, 64, 243–248.
Knisley, C. B., Kippenhan, M., & Brzoska, D. (2014). Conservation status of United States tiger beetles. Terrestrial Arthropod Reviews, 7, 93–145.
Montgomery, G. A., Belitz, M. W., Guralnick, R. P., & Tingley, M. W. (2021). Standards and best practices for monitoring and benchmarking insects. Frontiers in Ecology and Evolution, 8, 579193.
Moravec, J. (2018). Taxonomic revision of the Neotropical tiger beetle genera of the subtribe Odontocheilina—Vol. 1. Biosferiicka rezervace Dolni Morava.
Moravec, J. (2020). Taxonomic revision of the Neotropical tiger beetle genera of the subtribe Odontocheilina—Vol. 2. Biosferiicka rezervace Dolni Morava.
Pearson, D. L. (1985). The tiger beetles (Coleoptera: Cicindelidae) of the Tambopata Reserved Zone, Madre de Dios, Peru. Revista Peruana de Entomología, 27, 15–24.
Pearson, D. L. (1994). Lista preliminar de especies y clave para generos de los escarabajos tigre del Perú (Coleoptera: Cicindelidae). Revista Peruana de Entomología, 36, 55–58.
Pearson, D. L., & Anderson, J. J. (1985). Perching heights and nocturnal communal roosts of some tiger beetles (Coleoptera: Cicindelidae) in southeastern Peru. Biotropica, 17, 126–129.
Pearson, D. L., & Derr, J. A. (1986). Seasonal patterns of lowland forest floor arthropod abundance in southeastern Peru. Biotropica, 18, 244–256.
Schlesinger, M. D., & Novak, P. G. (2011). Status and conservation of an imperiled tiger beetle fauna in New York State, USA. Journal of Insect Conservation, 15, 839–852.
Schnabel, Z. E. (1938). The estimation of the total fish population of a lake. The American Mathematical Monthly, 45, 348–352.
For additional information or questions about this field report, please contact Dr. Lindsey Swierk (lindseyns@gmail.com), Director of Scientific Research for The Morpho Institute and Associate Director of Research for the Amazon Conservatory for Tropical Studies.
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