Document ID: chunk:federal_register_of_legislation:F2025L00287:reg:3:p62
Version: federal_register_of_legislation:F2025L00287
Segment Type: reg
Provision Reference: reg 3 (pt 62/276)
Character Range: 239418–243351

limited population size are particularly susceptible to all of these impacts.

Pressures resulting from small population size
Many of Norfolk Island's native species face pressures due to their small population sizes. Small, isolated populations are susceptible to genetic drift and inbreeding depression, both of which reduce the genetic diversity of a species (Frankham et al. 2014). Small populations are vulnerable to negative impacts of demographic stochasticity resulting from random fluctuations in reproductive rates, mortality processes and sex ratios. They are also more susceptible to the impact of environmental stochasticity, including the sort of normal climatic variation that produces 'good' and 'bad' years, as well as natural disasters such as fires, floods and storms.
Both plant and animal species will be affected by this class of threats in inverse proportion to their population sizes (or more accurately, to their effective population sizes). Thus, species such as the Norfolk Island morepork (current population size (N) = 25 individuals), Suter's striped glass-snail (N = 50 individuals), mountain procris (N = 26 individuals) and netted brakefern (N = 35 individuals) are likely to be particularly susceptible to genetic drift and inbreeding depression.

Key threatening processes
Nine key threatening processes listed under the EPBC Act are potentially relevant to the Norfolk Island Group. Table 17 indicates which of these processes have a threat abatement plan in place. Threat abatement plans are statutory documents aimed at lessening the impact of a key threatening process. All management actions implemented under this plan should align with the relevant threat abatement plans, including updated plans as they are released. Where appropriate, actions from the relevant threat abatement plans have been incorporated into management actions in this plan.
Table 17 Key threatening processes listed under the EPBC Act relevant to Norfolk Island Group
Key threatening process                                                                                          Threat abatement plan (TAP)
Land clearance                                                                                                   No TAP
Loss of terrestrial climatic habitat caused by anthropogenic emissions of greenhouse gases                       No TAP
Predation by exotic rats on Australian offshore islands of less than 1000 km2 (100,000 ha)                       Commonwealth of Australia (2009)
                                                                                                                 Threat abatement plan to reduce the impacts of exotic rodents on biodiversity on Australian offshore islands of less than 100 000 hectares
Predation by feral cats                                                                                          Commonwealth of Australia (2015a)
                                                                                                                 Threat abatement plan for predation by feral cats
Psittacine Circoviral (beak and feather) disease affecting endangered psittacine species                         2016 Non-statutory threat abatement advice
                                                                                                                 Threat Abatement Advice for the key threatening process 'Psittacine Circoviral (beak and feather) Disease affecting endangered psittacine species'
Incidental catch (or bycatch) of seabirds during oceanic longline fishing operations                             Commonwealth of Australia (2018b)
                                                                                                                 Threat abatement plan for the incidental catch (or bycatch) of seabirds during oceanic longline fishing operations
Injury and fatality to vertebrate marine life caused by ingestion of,