Venom effects and medical significance are different from toxicity rankings. Do not handle a snake on the basis of this summary.
Endemic to the Batanes Islands, with confirmed records on Batan and Sabtang. An arboreal pitviper with striking colour variation, documented in Mario Lutz’s field and husbandry account.
OccurrenceConfirmed
Islands named2
Natural history14 sourced topics
References7
Literature updated 2026-10-07 · Editorial review pending
Author field account from the Batanes Islands; draft dated 2009.
The current checklist backbone explicitly names Batan only. Sabtang therefore remains author-supplied manuscript evidence awaiting independent source verification; Itbayat is not treated as confirmed.
Ecology & habitat
Predominantly arboreal ambush predator. On Batan, the vegetated slopes and forest canopy around Mount Iraya form important habitat in a cool, windy, humid and typhoon-exposed climate.
Qualitative field and husbandry observations by the author.
Exact elevation limits, habitat occupancy and population proportions are not supported by a cited survey dataset in the draft and are not inferred here.
Diet & foraging
Sit-and-wait predator feeding mainly on birds, frogs and lizards; bats are taken occasionally. Field observations and stomach-content examinations support this prey spectrum.
Wild diet and behaviour as reported in the manuscript, supplemented by captive feeding observations.
The draft does not provide specimen counts, locality-level records or a quantitative diet dataset, so prey proportions and aerial-capture frequency remain unresolved.
Morphology & colour
10–11 supralabials; 12 infralabials; 170–178 ventrals; 58–66 subcaudals; 21 dorsal scale rows. Colour varies from yellow, brown and ochre to silver-grey, white and nearly black, with or without dark rhomboid or blotched markings. Females reach about 130 cm; males about 85 cm.
Author observations and descriptive ranges presented in the working draft.
Voucher specimens, sample sizes and measurement methods are not supplied in the draft; the ranges require comparison with formal taxonomic descriptions.
Conservation pressures
A highly restricted range, conversion of land to agriculture and pasture, illegal collection and high mortality during transport place the species under serious pressure.
Author account of habitat conditions, confiscated animals and trade observations.
No standardised population estimate or formal threat assessment is provided. Numerical population and transport-mortality estimates in the draft are not repeated as established facts.
Captive breeding
Successfully bred in captivity by Mario Lutz on Mindoro. The account documents the husbandry of adults and juveniles.
First-person captive management and breeding account.
The available working draft does not contain a complete, independently documented reproductive dataset, and these observations do not establish reproductive timing or success in the wild.
Venom
Venomous. Conspecific bites in captivity and during transport caused marked tissue damage and, in severe cases, death.
Non-clinical observations of conspecific envenoming.
This is not a clinical human envenoming study and provides no validated human risk profile, antivenom guidance or first-aid protocol. Human medical significance remains unresolved in this record.
Venom research
The venom triggers rapid clot formation, but the clots are weak and short-lived. This consumes fibrinogen, a protein needed for effective clotting. The overall effect therefore impairs coagulation rather than reliably stopping bleeding — a mechanism called pseudo-procoagulation.
Blood-clotting effects · 2025 study
Pooled venom from two adult males and two adult females; experiments used human plasma and isolated clotting components.
Clotting enzymes IXa and Xa were also inhibited, further weakening coagulation.
Antivenom findings
Both Thai Red Cross antivenoms showed laboratory cross-neutralisation. Overall, Hemato Polyvalent Antivenom outperformed Green Tree Pit Viper Antivenom; effects varied with venom concentration.
Clinical interpretation These are laboratory findings, not a clinical treatment trial. They establish neither a patient dose nor guaranteed effectiveness after a bite.
Figure 1 · clotting time; venom 20 µg/mL. Mean ± standard deviation; n = 3 assay replicates, not patients.
Literature documented · Results, Fig. 1 and Figs. 3–6; Methods §4.1
In-vitro experiments; Castillo and colleagues, Toxins (2025).
Clinical evidence
A published bite case documents severe damage after venom entered a finger joint. The 1997 report identifies the snake under the historical name Trimeresurus flavomaculatus mcgregori.
Literature documented · Abstract; Toxicon 35(6): 837–842
A single clinical case, not an estimate of typical bite severity.
The abstract does not establish treatment effectiveness or the frequency of this complication.
Reproduction
The species account records egg-laying reproduction. A verified Philippine clutch-size range, incubation interval and breeding calendar are not established here.
Reproductive mode reported for this named species.
Mode alone does not establish litter or clutch size, seasonal timing, or captive husbandry requirements.
Ecology & habitat
The species account characterises this snake as tree-dwelling. That broad ecological category does not establish canopy height, forest dependence or tolerance of habitat disturbance.
Species-level database summary; literature review, not expert validation.
The cited account does not establish population-wide variation or the conditions at every Philippine locality.
Reproduction
Audubon Zoo records document egg-laying: 11 clutches contained 2–11 eggs, and four viable clutches produced 23 hatchlings. Incubation took 45–54 days at 26.7 °C in that captive series.
Literature documented · pp. 359–360, historical zoo records
Captive observations; not a Philippine wild breeding calendar.
Clutch counts include unsuccessful clutches; husbandry context was incomplete.
Philippine distribution
The atlas records Trimeresurus mcgregori from these named Philippine areas: Batan, Sabtang. These are literature areas rather than a continuous range boundary.
Literature documented · Existing checklist occurrence statement and distribution review
The original evidence level is retained.
A country listing cannot establish an island or a precise locality.
Taxonomic context
Trimeresurus mcgregori is retained in the atlas’s dated checklist under Viperidae. The authority is TAYLOR 1919. Earlier names and the original source notes are preserved below for comparison.
Literature documented · Checklist identity and nomenclatural trail
Checklist verified 2026-09-06; not a newly revised taxonomic backbone.
Historical names can cover different biological concepts; synonyms should not be used to transfer records automatically.
Across the archipelago
Where this species is recorded
Northern PhilippinesN ↑
Documented islands: gold · island groups: dashed circles
Island-level records · not continuous habitat coverage. Dashed circles locate groups, not individual observations.
Philippine distribution
Documented places
2 named islands / island groups
Endemic to the Batanes Islands; confirmed on Batan and Sabtang.
Distribution record & sources
The Reptile Database: Philippines (Batan Island). Type locality: Batan Island, Philippines.
Lutz manuscript: confirmed on Batan and Sabtang; reports from Itbayat remain unconfirmed.
Known from Batan and Sabtang. Reports from Itbayat remain unconfirmed; targeted investigations did not confirm the species there.
Die Batanes Pit-Viper (Parias mcgregori): Ein Rasseporträt
The atlas records Trimeresurus mcgregori from these named Philippine areas: Batan, Sabtang. These are literature areas rather than a continuous range boundary.
Observe from a distance. Do not handle, corner or capture a snake to identify it. An incomplete venom account is not evidence that a species is safe to handle.
After a suspected snakebite, keep the person still and arrange urgent medical care. Avoid tight tourniquets, cutting, suction and unproven remedies. Do not wait to identify the snake before seeking help.
McGregor's pitviper, McGregor's Tree Viper · Batanes-Bambusotter
Authority
TAYLOR 1919
Year described
1919
Taxonomic status
Accepted species
Family
Viperidae
Genus
Trimeresurus
Species epithet
mcgregori
Persistent ID
PH-SERP-B5CFBA0DD0
Checklist checked
2026-09-06
Philippine occurrence
Status
Present
Confidence
Confirmed
Basis
2018 Philippine synopsis and current RDB listing, supplemented by Mario Lutz's Batanes field account
Islands named
Batan, Sabtang
Range noteEndemic to the Batanes Islands. Confirmed on Batan and Sabtang; Itbayat remains an unconfirmed report.
Source distribution statement
The Reptile Database: Philippines (Batan Island). Type locality: Batan Island, Philippines.
Lutz manuscript: confirmed on Batan and Sabtang; reports from Itbayat remain unconfirmed.
Trimeresurus mcgregori — The Reptile Database species account
Uetz, P.; Hallermann, J. et al. (editors)
Public species fields consulted for bounded biological summaries. Primary sources quoted within the database were not independently examined unless explicitly stated. The catalogue name may differ from the current source title.