Trapping Boiga irregularis on Guam Using Bird Odors

Fritts, Thomas H.; Scott, Norman J.; Smith, Brian E.

doi:10.2307/1564032

Cited by 19 publications

(14 citation statements)

References 4 publications

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“…We also recorded the greatest increase in small mammal encounters along forest edges, although rat encounters were also high in the forest interior. Snakes use multiple sensory modalities to locate prey 64 , 65 and may have selected edge habitats as good locations to locate prey. Laboratory and field experiments on BTS demonstrated that the combination of olfactory and visual cues created the strongest orientation response compared to either of these cues alone 66 .…”

Section: Discussionmentioning

confidence: 99%

Invasive brown treesnakes (Boiga irregularis) move short distances and have small activity areas in a high prey environment

Boback

Nafus

Adams

et al. 2022

Sci Rep

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Animal movements reflect temporal and spatial availability of resources as well as when, where, and how individuals access such resources. To test these relationships for a predatory reptile, we quantified the effects of prey abundance on the spatial ecology of invasive brown treesnakes (Boiga irregularis) on Guam. Five months after toxicant-mediated suppression of a brown treesnake population, we simultaneously used visual encounter surveys to generate relative rodent abundance and radiotelemetry of snakes to document movements of surviving snakes. After snake suppression, encounter rates for small mammals increased 22-fold and brown treesnakes had smaller mean daily movement distances (24 ± 13 m/day, $$\overline{x }$$ x ¯ ± SD) and activity areas (5.47 ± 5 ha) than all previous observations. Additionally, snakes frequenting forest edges, where our small mammal encounters were the highest, had smaller mean daily movement distances and three-dimensional activity volumes compared to those within the forest interior. Collectively, these results suggest that reduced movements by snakes were in part a response to increased prey availability. The impact of prey availability on snake movement may be a management consideration when attempting to control cryptic invasive species using tools that rely on movement of the target species to be effective.

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Section: Discussionmentioning

confidence: 99%

Invasive brown treesnakes (Boiga irregularis) move short distances and have small activity areas in a high prey environment

Boback

Nafus

Adams

et al. 2022

Sci Rep

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“…3). Although bird odour does attract BTS (Fritts et al 1989), testing has shown that traps with live mice are more effective than traps baited with live quail or soiled bedding (Rodda et al 1999), potentially because mice are active at night when BTS are foraging. Yackel Adams et al (2019) also found that mouselure traps had a higher overall CPUE than bird-lure traps on Guam when deployed together in the field.…”

Section: Discussionmentioning

confidence: 99%

Olfactory lures in predator control do not increase predation risk to birds in areas of conservation concern

Klug

Adams²,

Reed³

2021

Wildl. Res.

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Context Lethal control of predators is often undertaken to protect species of conservation concern. Traps are frequently baited to increase capture efficacy, but baited traps can potentially increase predation risk by attracting predators to protected areas. This is especially important if targeted predators can escape capture due to low trap success. Snake traps using live mouse lures may be beneficial if traps effectively remove snakes in the presence of birds and do not attract additional snakes to the area. Aims The present study evaluated whether mouse-lure traps in areas occupied by birds (simulated by deploying bird-lure traps) could influence predation risk from an invasive snake on Guam. Methods Snake traps were used, with Japanese quail (Coturnix japonica) as a proxy for predation risk, to assess if an adjacent trap with a mouse (Mus musculus) would attract brown treesnakes (Boiga irregularis) to a focal area and increase contact between an invasive snake and avian prey. Catch per unit effort (CPUE) at stations containing either a bird-lure trap, mouse-lure trap or pair of traps (i.e. one bird-lure and one mouse-lure trap) was evaluated. Key results Bird-lure traps paired with mouse-lure traps did not differ in CPUE from isolated bird-lure traps. At paired stations, CPUE of snakes in mouse-lure traps was 2.3× higher than bird-lure traps, suggesting mouse lures were capable of drawing snakes away from avian prey. Bird-lure traps at paired stations experienced a decay in captures over time, whereas CPUE for isolated bird-lure traps increased after 9 weeks and exceeded mouse-lure traps after 7 weeks. Conclusions Mouse lures did not increase the risk of snakes being captured in bird-lure traps. Instead, mouse-lure traps may have locally suppressed snakes, whereas stations without mouse-lure traps still had snakes in the focal area, putting avian prey at greater risk. However, snakes caught with bird lures tended to be larger and in better body condition, suggesting preference for avian prey over mammalian prey in larger snakes. Implications Strategic placement of olfactory traps within areas of conservation concern may be beneficial for protecting birds of conservation concern from an invasive snake predator.

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“…The empirical approach for synthetic brown tree snake attractants in the present study is similar to other studies and all have produced disappointing results. Attractiveness of several agents, including major components of carrion odor such as cadaverine and putrescine, predator lures, bird odors, rotten eggs, and rotten milk, is low (Chiszar et al 1997, Clark 1997, Fritts et al 1989, Shivik 1999, Shivik and Clark 1999a. It is highly unlikely that a single chemical will be found to be an attractant for snakes.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Bait Matrices and Chemical Lure Attractants for Brown Tree Snakes

Savarie¹,

Clark²

2006

vertebrate_pest_conference

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Brown tree snake introduction to the snake-free island of Guam has severely impacted its native terrestrial vertebrates and economy. These nocturnal predators have extirpated forest birds, caused drastic reductions of lizards, and there is a major concern that snakes could be dispersed to other areas through Guam's cargo transportation systems. Techniques to deter the spread of snakes include cargo inspection with detector dogs and live trapping using live mice as lures to reduce snake densities in cargo handling areas. Maintaining mice in traps is expensive, and an inanimate lure would be highly desirable. Oral baiting with dead neonatal mice (DNM) treated with acetaminophen is another technique being implemented for reducing snake populations. An objection to DNM is that they decompose and become putrid after 3-4 days. Consumption of 21 candidate bait matrices was compared to DNM in free-choice tests in individually caged snakes under laboratory conditions. Consumption of dead quail chicks and geckos was equivalent to DNM. Processed canned meat products, stew beef, and chicken were 30-50% as effective as DNM. Baits not consumed included dog blood, beef liver, and quail eggs. Under field conditions with live trapped snakes, consumption of 7 bait matrices was compared to DNM in 1-choice tests. DNM were preferred (55% consumption) over all other baits. Consumption of plastic lizards, chicken fat, and mealworms was 33%, 14%, and 13%, respectively. Odoriferous chemicals (n = 23), characteristic of decomposing animal flesh, were evaluated for their ability to attract snakes in the field. Chemicals were individually evaluated by placing them on tofu baits in PVC tubes (bait stations). Snake activity around the bait stations was monitored with infrared videography. Some of the 23 chemicals (i.e., L-methionine, 3-methyl-1-butanethiol) appeared to attract snakes to the tubes. However, no tofu baits treated with chemicals were consumed, whereas 100% of the snakes that visited tubes baited with DNM consumed the dead mice. These results, along with analysis of videos, indicate that chemicals may act as long distance lures but are insufficient for stimulating and initiating consumptive or appetitive search behaviors at close range.KEY WORDS: bait stations, baits, Boiga irregularis, brown tree snake, chemical lures, snake control, videography Proc. 22 nd Vertebr. Pest Conf. (R. M. Timm and J. M. O'Brien, Eds.) Published at Univ. of Calif., Davis. 2006. Pp. 483-488.

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Trapping Boiga irregularis on Guam Using Bird Odors

Cited by 19 publications

References 4 publications

Invasive brown treesnakes (Boiga irregularis) move short distances and have small activity areas in a high prey environment

Invasive brown treesnakes (Boiga irregularis) move short distances and have small activity areas in a high prey environment

Olfactory lures in predator control do not increase predation risk to birds in areas of conservation concern

Evaluation of Bait Matrices and Chemical Lure Attractants for Brown Tree Snakes

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