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Boulder Coolskink (Carinascincus microlepidotus)

The Boulder Coolskink is a small, live-bearing alpine skink endemic to mountainous areas of central and southern Tasmania. It uses rocky heath, scree, subalpine woodland and lake-edge habitat above the treeline, where clearing, rock removal, vegetation damage and disturbance can affect small, poorly connected subpopulations.

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

Breeding season

The Boulder Coolskink mates from December to March, ovulates in October to November, and gives birth to live young in September to October after an approximately one-year gestation. Females and shelters may be affected by works throughout the year, with particular care needed during winter sheltering and spring births.

Reproductive mode: Viviparous, giving birth to live young.

Litter size: 1 to 5 young, with a mean of approximately 2.1 to 2.5.

Gestation: Approximately one year, spanning two reproductive seasons. Females retain sperm over winter, and fully developed young are held until the following spring.

Size at birth: Approximately 26 mm snout-vent length.

Age at maturity: Females reach sexual maturity at 3 to 4 years.

Nest or egg sites: Not applicable because the species gives birth to live young. Birth-site dimensions are not stated, but breeding habitat includes alpine rocks, scree, crevices and low vegetation.

Breeding frequency: Biennial. A female may not produce young every year.

Confirm timing locally before works, because temperature and the occurrence of warm, sunny conditions can shift surface activity and the period when animals remain in alpine shelters.

  • Mating: Mating occurs from December to March. Pairs may remain together for an average of 29 days.
  • Gravid females: The reproductive cycle spans approximately one year. Females ovulate in October to November, carry developing young through winter and may retain fully developed young until births in the following September to October.
  • Births: Live births occur in spring, generally from September to October. Litters contain 1 to 5 young.
  • Newborns: Newborns are expected mainly after the September to October birth period. Newborn body size is approximately 26 mm snout-vent length; later juvenile abundance and emergence timing are not recorded.
  • Active period: The species is diurnal and is most readily observed on warm, sunny days. Activity is expected to be greatest in the warmer period, with feeding and favourable basking conditions documented from December to March; local altitude and temperature may shorten this period.
  • Winter inactivity: During cold alpine conditions, individuals shelter above the treeline in deep rock crevices or under rocks, and may shelter among low vegetation. The documents do not assign fixed winter months, so June to August represents a typical high-risk cold period rather than a confirmed species-wide schedule.
  • Highest clearing risk: Occupied habitat is used throughout the year, so clearing can harm adults and refuges in any month. Risk is highest from June to August when animals may be sheltering in rocks, crevices and vegetation, and from September to October when births occur and newborns are present.

Identification

This is a small alpine skink with a dark, often chequered appearance and very small scales. Identification can be difficult where it occurs with other Tasmanian coolskinks, including areas where hybridisation has been recorded.

Adults reach up to 70 mm snout to vent length. Newborns are approximately 26 mm snout to vent length. No body weight data are provided in the supplied sources.

The body is dark to olive brown, with dark markings forming a chequered pattern. It has a pale dorsolateral stripe, brown to black upper flanks that may have pale flecks, grey lower flanks with black flecks, and very small scales.

Identification: Similar species

The species can resemble the Tasmanian Mountain Skink and Tasmanian Tree Skink. The absence of a white midlateral stripe helps separate it from these species.

Compared with the Northern Snow Skink, it tends to have dark spots on its tiny scales. Small scales, the absence of a black vertebral stripe and the absence of a white midlateral stripe on the flanks support identification as a Boulder Coolskink.

Hybridisation with the Tasmanian Mountain Skink has been recorded in some regions. A specimen that cannot be identified confidently should be photographed, handled only where authorised, and referred to an experienced herpetologist.

Identification: Field signs and sex

The species is usually detected visually when basking on exposed rock faces or moving among low vegetation. When disturbed, it retreats into rock crevices or dense vegetation.

No reliable species-specific information is provided on tracks, scats, calls, nests, sloughs or eyeshine. No external sexing characters are specified in the supplied sources. Field identification should therefore rely on live or photographic features, location, habitat and expert confirmation.

Distribution: National range

The Boulder Coolskink is restricted to Tasmania. Its distribution is discontinuous, forming alpine or high-elevation sky islands rather than a continuous lowland range.

The species is known only from mountainous areas of central and southern Tasmania. It extends north to Mount Oakleigh and east to Mount Wellington, at approximately 800 to 1270 m elevation.

The known range occurs within protected areas, including Cradle Mountain-Lake St Clair National Park, Franklin-Gordon Wild Rivers National Park, Southwest National Park and other Tasmanian national parks and reserves.

Australian states: Tasmania only.

Bioregional setting: Tasmanian alpine and subalpine mountains. A specific IBRA bioregion is not named in the supplied sources.

Distribution: Strongholds and subpopulations

Named areas that contain habitat include Mount Wellington, the Cradle Mountain area and mountains within the south-west Tasmanian national park system. The species has a sky island distribution, and all populations are considered important because local extinctions are not readily recolonised.

Where it occurs, the species may be common, but the total population size is not known. The EPBC listing assessment identifies a restricted extent of occurrence and area of occupancy, fewer than five locations, and projected declines in habitat and mature individuals.

Population size: Not known.

Population trend: Projected decline in extent of occurrence, area of occupancy, habitat area and quality, and mature individuals.

Connectivity: Low. Home ranges are small and juvenile dispersal averages less than 12 m.

Habitat: Habitat types

The species occupies exposed, cool and often rocky habitat above the treeline. Retaining the complete mix of basking surfaces, low vegetation and deep refuges is important because individuals use these features within very small home ranges.

Habitat includes alpine rocky heath fields, subalpine woodlands, scree slopes and lake edges. The species occurs above the treeline and is associated with mountainous terrain.

It basks on exposed rock faces and shelters in crevices, under rocks and among low vegetation. Alpine heath may provide habitat where competition with other snow skinks has displaced individuals from more thermally suitable sites.

Habitat: Structural features and limits

Important structural features include exposed rocks that warm in sunlight, rock crevices, scree, low dense vegetation and humid shelter sites. Removing rocks or disturbing crevices can remove both basking and refuge habitat.

The usual elevation range is approximately 800 to 1270 m. The species is an alpine endemic with limited scope to move upslope because it already occurs near the upper elevational limits of its mountain habitats.

Foraging habitat: Diet and feeding sites

The Boulder Coolskink is a diurnal insectivore that forages in alpine rocky and low-vegetation habitat. It also feeds on honey bush, and has been recorded assisting with its seed dispersal and pollination.

The species is insectivorous. The supplied sources do not identify a complete prey list or quantify prey intake.

It feeds around exposed rocks and low vegetation in alpine heath, scree, subalpine woodland and lake-edge habitat. It has been recorded feeding on Richea scoparia, or honey bush, on Mount Wellington.

Foraging habitat: Foraging area

The home range is less than 15 m², so foraging habitat is likely to be close to shelter and basking sites. This makes local removal of rocks, low vegetation or moist refuges significant even where a larger area of surrounding habitat remains.

Recorded food plant: Richea scoparia, honey bush.

Home range: Less than 15 m².

Breeding habitat: Breeding biology

Breeding occurs in alpine habitat that provides close access to shelter, basking surfaces and low vegetation. Females retain developing young through winter and give birth in spring.

The species is viviparous. Mating occurs from December to March. Females retain sperm over winter, ovulate in October to November, complete embryonic development by March, and hold fully developed young until the following spring.

Females have a biennial reproductive cycle. A female may therefore not produce young every year. Males and females may form pairs for an average of 29 days during the mating season.

Breeding season: Mating from December to March; ovulation in October to November; births from September to October.

Litter size: 1 to 5 young, with a mean of approximately 2.1 to 2.5.

Gestation: Approximately one year, spanning two reproductive seasons.

Age at maturity: Females reach sexual maturity at 3 to 4 years.

Reproductive frequency: Females have a biennial reproductive cycle.

Lifespan: Not stated in the supplied sources.

Breeding habitat: Breeding habitat features

Breeding habitat should retain the alpine rock, scree and low-vegetation structure used by adults, together with secure crevices and humid shelter for females and young. The sources do not identify a nest or birth-site dimension.

Because young have limited dispersal and local extinctions are not readily recolonised, habitat removal around occupied rocky patches can affect recruitment as well as adult survival.

Sheltering habitat: Refuges

Shelter is provided by natural rock structure and dense low vegetation. The species remains associated with these features throughout the year, including during winter above the treeline.

The species overwinters above the treeline in deep crevices or under rocks. It also shelters in crevices, beneath rocks and among low vegetation during daily activity.

When disturbed, it retreats into rock crevices or nearby dense vegetation. Retain undisturbed boulder fields, scree, rock faces, crevice networks and low dense vegetation within occupied habitat.

Known refuge type: Deep rock crevices and spaces under rocks.

Other shelter: Dense low vegetation.

Refuge dimensions: Not specified in the supplied sources.

Sheltering habitat: Site handling

Do not move, bury, crush or store rocks from alpine habitat before a targeted ecological assessment. Avoid filling crevices, grading scree or stripping low vegetation where the species may occur.

Individuals have small home ranges, less than 15 m², so shelter and basking features may be concentrated within a small work area.

Threats: Habitat loss and fragmentation

Climate change is the primary threat, but project activities can directly remove the small rocky and vegetated habitat patches on which the species depends. The species is Endangered under the EPBC Act, so proposed clearing or disturbance in suitable Tasmanian alpine habitat requires early consideration of survey, avoidance and approval requirements.

Clearing, excavation, road formation, trenching, rock removal and construction can remove alpine rocky heath, scree, subalpine woodland, low vegetation and lake-edge habitat.

The species has a restricted range, small home ranges and limited juvenile dispersal. Fragmentation can isolate sky island subpopulations, and local extinctions are not readily recolonised.

  • Map rock faces, boulder fields, scree, crevices, low heath and lake edges before finalising infrastructure footprints.
  • Avoid placing access tracks, compounds, spoil, drainage works or storage areas on rocky habitat or dense low vegetation.
  • Keep occupied habitat patches connected where practicable and prevent indirect damage from vehicle access and material storage.

Threats: Climate change, drought and competition

Climate change is projected to shift suitable habitat upslope, reduce habitat area and quality, increase fragmentation and cause substantial declines in the species' metapopulation. Modelling cited in the conservation advice projects loss of about 60 percent of climatically suitable habitat by 2050 and about 93 percent by 2085 under the cited scenarios.

More frequent or severe drought is a concern because the species has a high rate of evaporative water loss and is expected to rely on humid areas. Warmer conditions may also allow metallic coolskinks and ocellated skinks to encroach into high-elevation habitat and compete for territory.

  • Protect humid refuges, low vegetation and natural drainage around occupied habitat.
  • Avoid actions that dry, divert or concentrate runoff through rocky heath and scree habitat.
  • Treat apparently marginal high-elevation habitat as potentially important where it may provide future climate refuge.

Threats: Predation, fire and hydrology

Feral cats occur in at least part of the range, including Mount Wellington National Park. Predation on Boulder Coolskinks is possible, but the extent of high-elevation use by cats and the population-level effect are not known.

The supplied sources do not identify fire, disease or road mortality as quantified species-specific threats. Fire, road construction and altered drainage can nevertheless remove or degrade the rocky heath, low vegetation and humid refuge features used by the species.

  • Control access by feral cats and avoid creating food or shelter opportunities for predators around work areas where this is consistent with approved management plans.
  • Plan fire management and post-fire works with the relevant land manager, because the species depends on alpine vegetation and rock refuges.
  • Use site-specific controls for dust, sediment, drainage diversion, water extraction and road edge disturbance near suitable habitat.

Survey methodology: 1. Habitat assessment and targeted searches

Survey for Boulder Coolskink should focus on alpine rocky heath, scree, subalpine woodland and lake edges above the treeline. No species-specific survey guideline or prescribed survey effort is provided in the supplied documents, so project ecologists should use a qualified herpetologist to set effort and document the basis for it.

Map and inspect alpine rocky heath fields, scree slopes, exposed rock faces, deep crevices, rocks, low vegetation and lake edges within the project area.

Prioritise sites at about 800 to 1270 m elevation, while recognising that suitable habitat may shift to higher elevations as the climate changes.

Search during the species’ diurnal activity period when individuals are likely to bask on exposed rocks, then inspect shelter sites such as rock crevices and dense low vegetation.

Do not rely on morphology alone where Tasmanian mountain skinks occur, because the two species can hybridise and may be difficult to distinguish in the field.

Adult size: Up to 70 mm snout to vent length

Newborn size: About 26 mm snout to vent length

Known elevation: About 800 to 1270 m

  • Record the location, elevation, habitat type, rock and vegetation features, weather, date, start and finish times, observers and all search effort.
  • Photograph suspected animals and retain diagnostic images for expert verification, particularly where the white midlateral stripe, black vertebral stripe or scale pattern is unclear.

Survey methodology: 2. Visual encounter and basking searches

Use systematic visual encounter searches along mapped rock faces, scree margins, alpine heath, subalpine woodland edges and lake margins.

Search exposed rocks and vegetation margins for small dark to olive brown skinks with a chequered pattern, pale dorsolateral stripe and dark spots on the small scales.

Allow time for animals to retreat into crevices or dense vegetation when approached, and inspect the likely refuge only where this can be done without damaging habitat.

Record negative searches as well as detections, because the species has a small home range of less than 15 m2 and limited juvenile dispersal, with mean juvenile dispersal of less than 12 m.

  • Use repeat searches across suitable habitat where access and weather permit, and state the number of observers, transect length or search area and search duration in the report.
  • Avoid turning or moving rocks unless this is authorised in the fauna management plan and can be done without damaging occupied refuges.

Survey methodology: 3. Timing and conditions

Schedule searches in the warmer part of the day when the species is likely to bask, subject to safe site access and project conditions.

Include the reproductive period in project planning: mating occurs from December to March, ovulation occurs in October to November, and young are generally born from September to October.

Avoid treating a single unsuccessful search as evidence of absence, particularly during cold, wet, windy or very dry conditions when activity and detectability may be reduced.

Use repeat or staged searches where works span different seasons, because females have a biennial reproductive cycle and carry developing young over winter.

Mating period: December to March

Ovulation period: October to November

Birth period: September to October

  • Record temperature, rainfall, wind, cloud, snow or frost conditions and whether exposed rocks were suitable for basking during each search.
  • Obtain specialist advice before using trapping, hand capture or artificial refuge methods, because no species-specific trapping effort or approved technique is provided in the supplied documents.

Survey methodology: Minimum effort and reporting

  • Prepare a project-specific survey design approved by a suitably experienced reptile ecologist, because the supplied documents do not prescribe nights, hours, trap nights, transect lengths or search areas for this species.
  • Survey all suitable habitat that may be directly or indirectly affected, including habitat close to the construction footprint where noise, vibration, access or altered drainage may affect rock refuges and low vegetation.
  • Obtain an expert identification or genetic and morphological assessment where a suspected animal may be a Tasmanian mountain skink or a hybrid.
  • Submit verified records, including negative survey information where requested, to the relevant Tasmanian wildlife records database and provide records to the Australian Government species records system where required by an approval.
  • Report the mapped extent of suitable habitat, all observations, survey effort, weather, identification basis, photographs, handling or relocation events and any injured or dead animals.

Before habitat disturbance: Avoid and minimise habitat loss

The species occurs in a restricted, sky island distribution in central and southern Tasmania. All populations are important because local extinctions are not readily recolonised, so avoid removing or isolating suitable alpine habitat wherever practicable.

Avoid alpine rocky heath, subalpine woodland, scree slopes, lake edges, exposed rock faces, deep crevices and low vegetation above the treeline.

Retain connected patches of suitable habitat and avoid creating isolated rock and heath remnants, because the species has limited dispersal and a small home range.

Keep construction access, laydown areas, spoil, drainage works and machinery outside retained rocky refuges and low heath wherever practicable.

Do not assume that protection status removes project risk: the entire known range is within protected areas, but direct disturbance and climate related habitat loss remain relevant threats.

  • Have the ecologist map habitat critical to survival before finalising the footprint.
  • Set site-specific no-go areas and protective buffers around occupied or potentially occupied rock refuges, with the distance justified by the habitat, construction method and risk of vibration or collapse.
  • Prevent changes to drainage, runoff, shading and sediment movement that could reduce humidity or alter alpine heath and scree habitat.

Before habitat disturbance: Approvals and project planning

The species is listed as Endangered under the EPBC Act, effective from 21 December 2023, so assess whether the proposed action may have a significant impact and whether an EPBC referral is required.

Confirm Tasmanian wildlife, national park, reserve, land manager and animal handling requirements before survey, capture, relocation or clearing begins.

Prepare a fauna management plan that identifies habitat, survey methods, authorised personnel, stop-work triggers, capture and relocation procedures, incident response and reporting requirements.

Stage works to keep the smallest practicable area open at one time and retain undisturbed habitat until the next work stage is ready.

  • Plan high-risk works outside periods when females may be carrying young where practicable, while recognising that the species has a prolonged reproductive cycle and no season is risk free.
  • Include a contingency for finding an occupied crevice, basking animal or previously unmapped subpopulation.
  • Consult relevant Tasmanian land managers and Indigenous custodians before works in areas of cultural significance.

Before habitat disturbance: Pre-clearance preparation

Complete a pre-clearance inspection of all habitat within the approved disturbance area and the nominated access and laydown areas.

Mark no-go habitat, occupied or suspected refuges, rock faces, scree, low heath and other retained features in the field before machinery arrives.

Fence or otherwise clearly delineate exclusion areas where fencing will not damage alpine vegetation or obstruct animal movement.

Brief all workers on the species’ appearance, its tendency to retreat into crevices or dense vegetation, the location of exclusion areas and the stop-work procedure.

Confirm that a suitably authorised fauna spotter catcher and a reptile ecologist are available for the planned clearing.

During habitat disturbance: Daily controls and machinery coordination

Boulder Coolskinks can retreat quickly into rock crevices or dense vegetation. Clearing should therefore be slow, supervised and staged, with machinery kept away from retained habitat and the fauna spotter catcher able to inspect the active work area.

Inspect exclusion fencing, habitat markers, access routes and retained refuges before work starts each day.

Hold a daily pre-start briefing covering the day’s footprint, machinery movements, spotter catcher position, stop-work signals and emergency contacts.

Use the smallest practicable clearing area and progress in a direction that allows animals to move towards retained suitable habitat rather than into the work zone.

Keep the fauna spotter catcher in a safe position with a clear view of the active clearing face, and stop machinery before the spotter catcher enters or inspects a feature.

Do not allow machinery, workers, spoil or materials to enter marked habitat or block access to retained crevices and vegetation.

  • Stop work immediately if an animal is seen, if a rock refuge collapses unexpectedly, if exclusion controls fail or if clearing reveals previously unmapped suitable habitat.
  • Reassess the method with the ecologist before restarting after a stop-work event.

During habitat disturbance: Handling and relocation

Only personnel authorised under the relevant approval and fauna management plan should capture, handle or relocate a skink.

If an animal is found, stop nearby machinery, keep people back, photograph it where safe, and allow it to retreat to retained habitat if it can do so without entering the active work area.

If capture is necessary, use an experienced reptile handler and minimise handling time, heat exposure, stress and distance moved.

Relocate an animal only to nearby retained habitat that matches its rocky alpine heath, scree, low vegetation or crevice shelter requirements and that is outside the work footprint.

Do not move animals long distances or across unsuitable habitat, because the species has limited juvenile dispersal and local populations are poorly connected.

  • Record the animal’s exact find location, identification, photographs, sex or life stage if known, capture method, release location, time, handler and condition.
  • Take injured animals to a veterinarian or appropriately authorised wildlife carer as soon as practicable, following the project approval and animal welfare requirements.

During habitat disturbance: Habitat features and incident records

Treat exposed rocks, boulder fields, deep crevices, scree, low alpine vegetation and rock faces as potential shelter or basking habitat, even when no animal is visible.

Do not break, fill, roll or stockpile rocks from potential refuges unless the approved method has been reviewed by the ecologist and fauna spotter catcher.

Prevent sediment, concrete washout, fuel, weeds and altered runoff from entering retained alpine heath, scree or lake-edge habitat.

Record all observations, captures, relocations, injuries, mortalities, habitat damage, equipment failures, exclusion breaches and daily clearing areas.

  • Notify the project manager and relevant regulator or land manager of any mortality, injury, unapproved habitat damage or repeated stop-work event in accordance with the approval.
  • Update the habitat map and fauna management plan when a new location or previously unrecognised habitat type is identified.

After habitat disturbance: Post-clearance inspection

Post-clearance checks should confirm that no animals remain in the disturbed area, that retained refuges are intact and that project controls have not isolated suitable habitat. Monitoring should test whether the species persists at affected sites and whether observed change matches modelled decline.

Complete a fauna spotter catcher inspection of the cleared footprint, stockpiles, temporary access areas and retained habitat edges before demobilising clearing crews.

Inspect exposed rocks, crevices, dense low vegetation and areas where animals could have been trapped or covered by spoil.

Remove temporary materials and restore safe access to retained habitat without disturbing occupied refuges.

Check exclusion fencing and no-go markers after each work stage and after high rainfall, earthworks or vehicle movements.

  • Record the date, area checked, observers, search conditions, findings and any corrective action.
  • Do not declare an area clear solely because no skink was observed during one inspection.

After habitat disturbance: Monitoring and reporting

Implement site monitoring where the project removes, fragments or alters suitable habitat, with methods and duration set by the project ecologist and approval conditions.

Use repeat monitoring to detect changes in occupancy, abundance, habitat condition and use of retained refuges.

Compare monitoring results with modelled predictions of population decline and revise the monitoring or management approach if observed results differ materially.

Report verified records and project impacts to the relevant Tasmanian wildlife database, land manager and approval agency.

  • Maintain records of habitat retained, habitat disturbed, rehabilitation completed, animals handled, injuries, mortalities, incidents and corrective actions.
  • Keep monitoring data linked to mapped locations so that future surveys can identify whether local populations persist.

After habitat disturbance: Controls, offsets and compliance

Maintain no-go areas, drainage controls, sediment controls and access restrictions for as long as construction impacts could affect retained habitat.

Repair damaged exclusion fencing and reinstate habitat protection after each construction stage.

If an approval requires an offset or compensatory action, ensure it protects suitable alpine habitat and addresses the species’ limited dispersal and restricted distribution.

Use offsets only after avoidance, minimisation and rehabilitation measures have been applied and documented.

Rehabilitation actions: Restore habitat structure

Rehabilitation should restore the physical shelter and low alpine vegetation used by Boulder Coolskinks, while maintaining cool, humid and connected habitat. The supplied documents do not specify a planting list, nest-box design or rehabilitation success thresholds, so these should be set with Tasmanian alpine vegetation specialists and the land manager.

Reinstate stable rocks, boulders, scree and crevice-forming features where they were removed or displaced, using locally appropriate material and a design that does not create unsafe collapse or erosion risk.

Re-establish low alpine heath and subalpine vegetation on disturbed ground using locally sourced provenance and methods approved for the relevant reserve or protected area.

Restore lake-edge and drainage conditions where works have altered moisture, runoff or sediment movement.

Reconnect retained habitat patches where practicable, because local extinctions are not readily recolonised and juvenile dispersal is limited.

  • Keep restored rock and vegetation features free of spoil, machinery access and construction materials.
  • Do not create dense tall vegetation or structures that replace the open rocky basking areas used by the species.

Rehabilitation actions: Weed, predator and fire management

Control weeds and prevent introduction of soil or plant material that could alter alpine heath and scree habitat.

Assess feral cat activity as part of site management, particularly where cats may reach high elevation habitat, and apply approved control measures if required.

Develop fire management with the land manager and Indigenous custodians so that fire does not remove refuge rocks, low vegetation or habitat connectivity.

Use Caring for Country knowledge and agreed cultural information protocols when Indigenous knowledge can improve habitat management.

  • Monitor for new predator sign, weed invasion, erosion and changes in low vegetation around rehabilitated areas.
  • Do not apply fire or predator control without the relevant environmental, animal welfare and land manager approvals.

Rehabilitation actions: Monitoring and success measures

Monitor rehabilitation for survival and cover of native alpine vegetation, stability of restored rocks and crevices, weed presence, erosion, moisture condition and connectivity to retained habitat.

Repeat targeted reptile searches during suitable basking conditions and record whether Boulder Coolskinks use restored or retained refuges.

Use the species’ presence, habitat condition and persistence of nearby subpopulations as key outcomes, rather than relying only on vegetation establishment.

Set project-specific timeframes, methods and performance thresholds with the approval agency and land manager because the supplied documents do not provide standard rehabilitation targets.

  • Continue monitoring until the agreed habitat and fauna outcomes are met or the regulator approves an alternative action.
  • Document failed plant establishment, rock movement, weed spread, predator activity and any species decline, then implement corrective works.

Sources