Register      Login
Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats
Shopping Cart: ( empty )
You are here: Home > Journals > WR > WR24085
RESEARCH ARTICLE (Open Access)
Contents Vol 52(4)

Behavioral plasticity in detection height of an invasive, arboreal snake based on size, condition, and prey

Melia G. Nafus https://orcid.org/0000-0002-7325-3055 A * , Levi N. Gray B D , Page E. Klug https://orcid.org/0000-0002-0836-3901 C , Gordon H. Rodda B and Scott M. Goetz A E
+ Author Affiliations
- Author Affiliations

A U.S. Geological Survey, Pacific Island Ecosystems Research Center, Hawai‘i Volcanoes National Park, Hawai‘i, HI 96718, USA.

B U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO 85026, USA.

C United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Department of Biological Sciences, North Dakota State University, Fargo, ND 58102, USA.

D Present address: U.S. Fish and Wildlife Service, Pacific Southwest Region Headquarters, Sacramento, CA 95825, USA.

E Present address: United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, CO 85026, USA.

* Correspondence to: mnafus@usgs.gov

Handling Editor: Catherine Collins

Wildlife Research 52, WR24085 https://doi.org/10.1071/WR24085
Submitted: 17 May 2024  Accepted: 4 March 2025  Published: 1 April 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution 4.0 International License (CC BY)

Abstract

Context

Animals may adjust their behavior in predictable ways to balance tradeoffs between resource acquisition and survival or fecundity. Microhabitat selection based on individual traits or environmental conditions is one measure of risk–reward tradeoffs by individuals.

Aims

We used data from observational and manipulative studies to investigate whether an arboreal snake (brown treesnake, Boiga irregularis) had context-dependent behavior based on the relationship between estimated prey availability, body condition, size, and detection height (microhabitat use) in two Mariana Islands.

Methods

We used observational data collected in four study sites and data from a manipulative study that we collected over a 5-year period. The observational data focused on four sites with different counts of three prey types, including lizards, birds, and small mammals. During the manipulative study we removed snakes, which resulted in increased prey counts over time. Using these two approaches, we tested whether prey counts predicted body condition and then evaluated how prey counts, snake size, and snake condition interactively predicted the detection height of captured individuals.

Key results

We found that body condition was greater at sites or in years with greater prey counts across both the observational and manipulative studies. We also found that snakes displayed differential microhabitat use based on both their condition and size. Larger snakes tended to be detected lower than smaller snakes, but only at sites or during years with few bird or small mammal counts. Snakes at sites with greater mammal and bird counts had a positive relationship between size and detection height. Snakes with greater condition scores tended to be detected higher irrespective of size, but this was also dependent on prey counts. At sites with low bird counts, snakes that were in better condition tended to be closer to the ground.

Conclusions

Brown treesnakes modified microhabitat use based on their condition, size, and the number or type of prey available. Our findings were consistent with a hypothesis that they optimized habitat use to secure food resources and maximize survival.

Implications

Context-dependent behavioral plasticity may be an important consideration for management of reptiles for population control or growth.

Keywords: behavior, Boiga irregularis, brown treesnake, context dependent, invasive species, microhabitat use, prey availability, prey richness.

References

Akinwande MO, Dikko HG, Samson A (2015) Variance inflation factor: as a condition for the inclusion of suppressor variable(s) in regression analysis. Open Journal of Statistics 5, 754-767.
| Crossref | Google Scholar |

Anholt BR, Werner EE (1995) Interaction between food availability and predation mortality mediated by adaptive behavior. Ecology 76, 2230-2234.
| Crossref | Google Scholar |

Barnhart PD, Quiogue ZC, Frasch ER, Vice DL, Hopkins CB, Yackel Adams AA, Reed RN, Nafus MG (2022) Boiga irregularis (Brown Treesnake). Herpetological Review 53, 444-445.
| Google Scholar |

Blouin-Demers G, Weatherhead PJ (2001) An experimental test of the link between foraging, habitat selection and thermoregulation in black rat snakes Elaphe obsoleta obsoleta. Journal of Animal Ecology 70, 1006-1013.
| Crossref | Google Scholar |

Boback SM, Nafus MG, Yackel Adams AA, Reed RN (2022) Invasive brown treesnakes (Boiga irregularis) move short distances and have small activity areas in a high prey environment. Scientific Reports 12, 12705.
| Crossref | Google Scholar |

Campbell EW, III, Adams AAY, Converse SJ, Fritts TH, Rodda GH (2012) Do predators control prey species abundance? An experimental test with brown treesnakes on Guam. Ecology 93, 1194-1203.
| Crossref | Google Scholar |

Citadini JM, Navas CA (2013) Inter-individual variation and temperature-dependent antipredator behavior in the snake Tomodon dorsatus (Dipsadidae). Behavioural Processes 97, 11-17.
| Crossref | Google Scholar |

Cooper W (2000) Tradeoffs between predation risk and feeding in a lizard, the broad-headed skink (Eumeces laticeps). Behaviour 137, 1175-1189.
| Crossref | Google Scholar |

Creel S, Christianson D (2008) Relationships between direct predation and risk effects. Trends in Ecology & Evolution 23, 194-201.
| Crossref | Google Scholar | PubMed |

Domenici P (2010) Context-dependent variability in the components of fish escape response: integrating locomotor performance and behavior. Journal of Experimental Zoology Part A: Ecological Genetics and Physiology 313A, 59-79.
| Crossref | Google Scholar |

Downes S (2001) Trading heat and food for safety: costs of predator avoidance in a lizard. Ecology 82, 2870-2881.
| Crossref | Google Scholar |

Downes S, Shine R (1998) Heat, safety or solitude? Using habitat selection experiments to identify a lizard’s priorities. Animal Behaviour 55, 1387-1396.
| Crossref | Google Scholar |

Fritts TH, Rodda GH (1998) The role of introduced species in the degradation of island ecosystems: a case history of Guam. Annual Review of Ecology and Systematics 29, 113-140.
| Crossref | Google Scholar |

Glaudas X, Alexander GJ (2017) Food supplementation affects the foraging ecology of a low-energy, ambush-foraging snake. Behavioral Ecology and Sociobiology 71, 5.
| Crossref | Google Scholar |

Glaudas X, Kearney TC, Alexander GJ (2017) To hold or not to hold? The effects of prey type and size on the predatory strategy of a venomous snake. Journal of Zoology 302, 211-218.
| Crossref | Google Scholar |

Goetz SM, Nafus MG (2024) Guam, Andersen Air Force Base housing area visual surveys for brown treesnakes (Boiga irregularis) and associated tree data, December 2019–November 2022. U.S. Geological Survey data release. Available at https://doi.org/10.5066/P14Q2JCZ

Gordon DM (2011) The fusion of behavioral ecology and ecology. Behavioral Ecology 22, 225-230.
| Crossref | Google Scholar |

Hammond KA, Spotila JR, Standora EA (1988) Basking behavior of the turtle Pseudemys scripta: effects of digestive state, acclimation temperature, sex, and season. Physiological Zoology 61, 69-77.
| Crossref | Google Scholar |

Heithaus MR, Wirsing AJ, Burkholder D, Thomson J, Dill LM (2009) Towards a predictive framework for predator risk effects: the interaction of landscape features and prey escape tactics. Journal of Animal Ecology 78, 556-562.
| Crossref | Google Scholar |

Hoefer KM, Jayne BC (2013) Three-dimensional locations of destinations have species-dependent effects on the choice of paths and the gap-bridging performance of arboreal snakes. Journal of Experimental Zoology Part A: Ecological Genetics and Physiology 319, 124-137.
| Crossref | Google Scholar |

Hossie TJ, Murray DL (2011) Effects of structural refuge and density on foraging behaviour and mortality of hungry tadpoles subject to predation risk. Ethology 117, 777-785.
| Crossref | Google Scholar |

Jayne BC, Byrnes G (2015) The effects of slope and branch structure on the locomotion of a specialized arboreal colubrid snake (Boiga irregularis). Journal of Experimental Zoology Part A: Ecological Genetics and Physiology 323, 309-321.
| Crossref | Google Scholar |

Jayne BC, Riley MA (2007) Scaling of the axial morphology and gap-bridging ability of the brown tree snake, Boiga irregularis. Journal of Experimental Biology 210, 1148-1160.
| Crossref | Google Scholar |

Klecka J, Boukal DS (2014) The effect of habitat structure on prey mortality depends on predator and prey microhabitat use. Oecologia 176, 183-191.
| Crossref | Google Scholar |

Klug PE, Yackel Adams AA, Siers SR, Brindock KM, Mosher SM, Mazurek MJ, Pitt WC, Reed RN (2021) Locally abundant, endangered Mariana swiftlets impact the abundance, behavior, and body condition of an invasive predator. Oecologia 195, 1083-1097.
| Crossref | Google Scholar |

Klug PE, Yackel Adams AA, Reed RN (2022) Olfactory lures in predator control do not increase predation risk to birds in areas of conservation concern. Wildlife Research 49, 183-192.
| Crossref | Google Scholar |

Knox AJ, Lardner B, Yackel Adams A, Reed RN (2018) Evaluating airsoft electric guns for control of invasive brown treesnakes. Wildlife Society Bulletin 42, 534-539.
| Crossref | Google Scholar |

Lardner B, Savidge JA, Rodda GH, Reed RN (2009) Prey preferences and prey acceptance in juvenile brown treesnakes (Boiga irregularis). Herpetological Conservation and Biology 4, 313-323.
| Google Scholar |

Lenth R (2024) emmeans: estimated marginal means, aka least-squares means. R package version 1.10.0. Available at https://CRAN.R-project.org/package=emmeans

Mackessy SP, Sixberry NM, Heyborne WH, Fritts T (2006) Venom of the brown treesnake, Boiga irregularis: ontogenetic shifts and taxa-specific toxicity. Toxicon 47, 537-548.
| Crossref | Google Scholar |

Merems JL, Shipley LA, Levi T, Ruprecht J, Clark DA, Wisdom MJ, Jackson NJ, Stewart KM, Long RA (2020) Nutritional-landscape models link habitat use to condition of mule deer (Odocoileus hemionus). Frontiers in Ecology and Evolution 8, 98.
| Crossref | Google Scholar |

Montgomery RA, Vucetich JA, Peterson RO, Roloff GJ, Millenbah KF (2013) The influence of winter severity, predation and senescence on moose habitat use. Journal of Animal Ecology 82, 301-309.
| Crossref | Google Scholar |

Nafus MG, Gray LN (2024) Quantifying the importance of ontogeny and prey type in modeling top-down and bottom-up effects of an ectothermic predator. Scientific Reports 14, 21601.
| Crossref | Google Scholar |

Nafus MG, Savidge JA, Yackel Adams AA, Christy MT, Reed RN (2018a) Passive restoration following ungulate removal in a highly disturbed tropical wet forest devoid of native seed dispersers. Restoration Ecology 26, 331-337.
| Crossref | Google Scholar |

Nafus MG, Yackel Adams AA, Klug PE, Rodda GH (2018b) Habitat type and structure affect trap capture success of an invasive snake across variable densities. Ecosphere 9, e02339.
| Crossref | Google Scholar |

Nafus MG, Yackel Adams AA, Boback SM, Siers SR, Reed RN (2020) Behavior, size, and body condition predict susceptibility to management and reflect post-treatment frequency shifts in an invasive snake. Global Ecology and Conservation 21, e00834.
| Crossref | Google Scholar |

Nafus MG, Xiong PX, Paxton EH, Yackel Adams AA, Goetz SM (2021) Foraging behavior in a generalist snake (brown treesnake, Boiga irregularis) with implications for avian reintroduction and recovery. Applied Animal Behaviour Science 243, 105450.
| Crossref | Google Scholar |

Nafus MG, Siers SR, Levine BA, Quiogue ZC, Yackel Adams AA (2022) Demographic response of brown treesnakes to extended population suppression. The Journal of Wildlife Management 86, e22136.
| Crossref | Google Scholar |

Nafus MG, Collins AF, Viernes MC, Hopkins CB, Nacpil A (2023) Guam, USGS Closed Population (NWFN), an experimental eradication of brown treesnakes in a 5-ha study site, 2016–2023. U.S. Geological Survey data release. Available at https://doi.org/10.5066/P9QRWKQB

Nafus MG, Reyes A, Fies T, Goetz SM (2024a) Adaptive resource management: achieving functional eradication of invasive snakes to benefit avian conservation. Journal of Applied Ecology 61, 733-745.
| Crossref | Google Scholar |

Nafus MG, Barnhart PD, Collins AF, Goetz SM, Hopkins CB, Klug PE, Rodda GH, Viernes MC, Yackel Adams AA (2024b) Guam, data on the height at which brown treesnakes were detected at four sites on Guam, 2007–2023. U.S. Geological Survey data release. Available at https://doi.org/10.5066/P93K6LG5

Perry G, Pianka ER (1997) Animal foraging: past, present and future. Trends in Ecology & Evolution 12, 360-364.
| Crossref | Google Scholar |

R Core Team (2020) R – the R project for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Available at https://www.r-project.org/ [accessed February 2020]

Rodda GH (1992) Foraging behaviour of the brown tree snake, Boiga irregularis. Herpetological Journal 2, 110-114.
| Google Scholar |

Rodda GH, Fritts TH (1992) The impact of the introduction of the Colubrid Snake Boiga irregularis on Guam’s lizards. Journal of Herpetology 26, 166-174.
| Crossref | Google Scholar |

Rodda GH, Reed RN (2007) Size-based trends and management implications of microhabitat utilization by brown treesnakes, with an emphasis on juvenile snakes. In ‘Managing vertebrate invasive species: proceedings of an international symposium’. pp. 257–267. (US Department of Agriculture National Wildlife Research Center, National Wildlife Research Center)

Rodda GH, Fritts TH, Reichel J (1991) The distributional patterns of reptiles and amphibians in the Mariana Islands. Micronesica 24, 195-210.
| Google Scholar |

Rodda GH, Fritts TH, Conry PJ (1992) Origin and population growth of the brown tree snake, Boiga irregularis, on Guam. Pacific Science 46, 46-57.
| Google Scholar |

Rodda GH, Savidge JA, Tyrrell CL, Christy MT, Ellingson AR (2007) Size bias in visual searches and trapping of brown treesnakes on Guam. The Journal of Wildlife Management 71, 656-661.
| Crossref | Google Scholar |

Rodda GH, Dean-Bradley K, Savidge JA, Christy MT, Tyrrell CL (2008) Post-colonization reversal of selection pressure on dispersal behavior of the brown treesnake, Boiga irregularis, on Guam. South American Journal of Herpetology 3, 123-134.
| Crossref | Google Scholar |

Rodda GH, Dean-Bradley K, Campbell EW, Fritts TH, Lardner B, Yackel Adams AA, Reed RN (2015) Stability of detectability over 17 years at a single site and other lizard detection comparisons from Guam. Journal of Herpetology 49, 513-521.
| Crossref | Google Scholar |

Royama T (1981) Evaluation of mortality factors in insect life table analysis. Ecological Monographs 51, 495-505.
| Crossref | Google Scholar |

Savidge JA (1987) Extinction of an island forest avifauna by an introduced snake. Ecology 68, 660-668.
| Crossref | Google Scholar |

Savidge JA (1988) Food habits of Boiga irregularis, an introduced predator on Guam. Journal of Herpetology 22, 275-282.
| Crossref | Google Scholar |

Secor SM, Nagy KA (1994) Bioenergetic correlates of foraging mode for the snakes Crotalus Cerastes and Masticophis Flagellum. Ecology 75, 1600-1614.
| Crossref | Google Scholar |

Siers S, Savidge J, Demeulenaere E (2017) Restoration plan for the Habitat Management Unit, Naval support activity Andersen, Guam. Colorado State University, Fort Collins, CO, p. 226.

Siers SR, Yackel Adams AA, Reed RN (2018) Behavioral differences following ingestion of large meals and consequences for management of a harmful invasive snake: a field experiment. Ecology and Evolution 8, 10075-10093.
| Crossref | Google Scholar |

Skelhorn J, Ruxton GD (2013) Size-dependent microhabitat selection by masquerading prey. Behavioral Ecology 24, 89-97.
| Crossref | Google Scholar |

Taylor Q, Cox CL (2019) Evidence of predation risk increases with body size in a diminutive snake. Journal of Zoology 307, 141-148.
| Crossref | Google Scholar |

Thaler R, Ortega Z, Ferreira VL (2022) Extrinsic traits consistently drive microhabitat decisions of an arboreal snake, independently of sex and personality. Behavioural Processes 199, 104649.
| Crossref | Google Scholar |

Tversky A, Simonson I (1993) Context-dependent preferences. Management Science 39, 1179-1189.
| Crossref | Google Scholar |

USGS (2023) Cocos Island, Guam Brown Treesnake Rapid Response visual survey and capture data, 10/2020-05/2023. U.S. Geological Survey data release. Available at https://doi.org/10.5066/P9MT1JNO

van Oers K, Klunder M, Drent PJ (2005) Context dependence of personalities: risk-taking behavior in a social and a nonsocial situation. Behavioral Ecology 16, 716-723.
| Crossref | Google Scholar |

Webb JK, Whiting MJ (2005) Why don’t small snakes bask? Juvenile broad-headed snakes trade thermal benefits for safety. Oikos 110, 515-522.
| Crossref | Google Scholar |

Wiewel AS, Yackel Adams AA, Rodda GH (2009a) Distribution, density, and biomass of introduced small mammals in the southern Mariana Islands. Pacific Science 63, 205-222.
| Crossref | Google Scholar |

Wiewel AS, Adams AAY, Rodda GH (2009b) Evaluating abundance estimate precision and the assumptions of a count-based index for small mammals. The Journal of Wildlife Management 73, 761-771.
| Crossref | Google Scholar |

Wiles GJ (1987) The status of fruit bats on Guam. Pacific Science 41, 148-157.
| Google Scholar |

Wiles GJ, Bart J, Beck RE, Jr., Aguon CF (2003) Impacts of the brown tree snake: patterns of decline and species persistence in Guam’s avifauna. Conservation Biology 17, 1350-1360.
| Crossref | Google Scholar |

Yackel Adams AA, Nafus MG, Klug PE, Lardner B, Mazurek MJ, Savidge JA, Reed RN (2019) Contact rates with nesting birds before and after invasive snake removal: estimating the effects of trap-based control. NeoBiota 49, 1-17.
| Crossref | Google Scholar |

Yeo M-H, Patil UD, Chang A, King R (2023) Changing trends in temperatures and rainfalls in the western Pacific: Guam. Climate 11, 81.
| Crossref | Google Scholar |