Stercorariidae
Enable an agent to recognise Stercorariidae as a bird family, organise evidence about its members, and judge observations and conservation actions at the appropriate taxonomic and geographic level.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an agent to recognise Stercorariidae as a bird family, organise evidence about its members, and judge observations and conservation actions at the appropriate taxonomic and geographic level.
Stercorariidae is a family of predatory seabirds in the order Charadriiformes, comprising the skuas and jaegers, which obtain food by hunting, scavenging and stealing prey from other birds.
It can be Reconcile skua and jaeger records across common names, synonyms and checklist versions.; Assess whether an observation supports family identification or a narrower species assignment.; Compare morphology and life-history evidence while preserving species, age and sex distinctions.; Summarise seasonal range and feeding relationships without treating all skuas as ecologically identical.; Identify evidence gaps and route proposed monitoring or disturbance-sensitive activity to species, site and legal reviews..
Distinguishing features
Require family rank: Stercorariidae is not interchangeable with the genus Stercorarius or an individual skua species.
Treat 'skua' and 'jaeger' as overlapping common-name usage rather than separate family identities; Birds New Zealand describes the smaller skuas as jaegers. [Taxonomic treatment](https://www.birdsnz.org.nz/society-publications/checklist/charadriiformes-waders-skuas-gulls-and-terns/)
Resolve records using Catharacta against the selected checklist rather than excluding them by genus spelling; Birds New Zealand places all skua species in Stercorarius. [Taxonomic treatment](https://www.birdsnz.org.nz/society-publications/checklist/charadriiformes-waders-skuas-gulls-and-terns/)
For field recognition against gulls and terns, require a documented combination of bill structure, wing pattern, tail shape and flight behaviour assessed for age and plumage; food stealing alone is insufficient.
Do not infer evolutionary placement solely from size or superficial plumage similarity: published research reports discordance between morphological and genetic relationships in skuas. [Primary research](https://pmc.ncbi.nlm.nih.gov/articles/PMC1688246/)
Scope
+ Family identity, nomenclatural authority and membership under a specified taxonomic treatment
+ Recognition of skuas and jaegers, including age, plumage and identification uncertainty
+ Species-linked life stages, breeding characteristics and sexual dimorphism
+ Seasonal distribution, marine habitat use and breeding-site relationships
+ Feeding interactions and conservation evidence with explicit species and population scope
- Complete species accounts and species-specific diagnostic keys
- Individual bird medical records, rehabilitation and captive husbandry
- Full models of gulls, terns and other neighbouring bird families
- Marine ecosystem management beyond documented relationships with skuas
- Detailed population monitoring datasets and jurisdiction-specific wildlife regulations
Characteristics
- Family taxon concept
- Stercorariidae; rank family; registry id vr.tr.stercorariidae Prevents family summaries from being mistaken for species or individual records.
- Nomenclatural authority
- Attributed author and date linked to a checked nomenclatural source Separates authorship of the name from the checklist defining its current membership.
- Taxonomic treatment and membership
- Checklist, version, date, accepted genera and species, and synonym mappings Makes differing uses of Stercorarius and Catharacta interpretable.
- External taxon identifiers
- Verified GBIF and NCBI family identifiers, retrieval dates and concept matches; unresolved when unchecked Supports evidence linkage without attaching a species or genus identifier to the family.
- Identification resolution
- Family confirmed; species supported; species unresolved; possible hybrid; identification disputed Allows useful observations to remain at the narrowest defensible rank.
- Morphology evidence
- Mass in g; wing, bill and tail measurements in mm; method, species, age and sex attached Prevents pooled measurements from concealing differences among skua species and life stages.
- Life stage and plumage
- Egg; chick; juvenile; immature; adult; unknown, with separate plumage, morph and moult descriptors Makes identification and behavioural comparisons conditional on development and plumage.
- Sex and dimorphism evidence
- Female; male; unknown, with determination method and species-specific comparative evidence Avoids unsupported sex assignment from apparent size or colour.
- Seasonal range role
- Species or population linked to breeding, passage, nonbreeding or vagrant occurrence, with dates and location Separates nesting distribution from movement and offshore occurrence.
- Feeding interaction
- Kleptoparasitism; predation; scavenging; other observed feeding; unresolved Distinguishes observed food acquisition from assumptions based on the skua name.
- Conservation assessment scope
- Assessed species or population, assessment system, category, year, geography and trend evidence Prevents a member species' status from becoming an unsupported family-wide status.
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 7 bundles · 13 layers · 20 findings · 39 questions.
Taxonomic identity Establish which family concept the registry entry represents and how member names resolve.
Skua nomenclature and genus treatments can otherwise fragment one family into incompatible records.
Family name and rank
Anchor Stercorariidae to its nomenclature and taxonomic level.
Family concept anchor
Record the family name, checked authorship and parent placement separately from species binomials.
- Which source establishes the authorship, date and parent placement of Stercorariidae? provenance
- Does the incoming record describe the family, a member species, a population or an individual? boundary
Membership and crosswalks
Interpret accepted names and historical combinations through a versioned checklist.
Skua name resolution
Maintain treatment-specific membership and mappings for Stercorarius, Catharacta and regional common names.
- Which checklist version defines the included genera and species? provenance
- How does that treatment resolve Catharacta combinations and names using 'jaeger'? definition
- Which GBIF and NCBI identifiers have been verified to represent the same family concept? provenance
Recognition and variation Evaluate evidence for skua identification without overstating species, age or sex resolution.
Variable plumage and resemblance among seabirds make single-feature identification unreliable.
Family recognition
Test a candidate identification against plausible gull and tern alternatives.
Combined field evidence
Record visible bill, wing and tail features alongside flight observations and viewing limitations.
- Which observed combination of bill structure, wing pattern, tail shape and flight supports Stercorariidae? measurement
- Which gull or tern alternatives remain plausible under the observed age, distance and lighting? boundary
Within-family variation
Separate species distinctions from age, moult, colour variation and uncertain sex.
Conditional identification
Require species-linked interpretation of measurements and plumage rather than a universal skua appearance.
- How do age, moult and documented colour morph affect the proposed identification? boundary
- What measurement or validated method supports any sex assignment or claim of sexual dimorphism? measurement
- Should this record remain at family level or be flagged for specialist review? action
Life cycle and breeding Organise development and reproduction as evidence about particular skua species and populations.
Breeding condition and developmental stage affect identification, population interpretation and disturbance decisions.
Developmental stages
Distinguish physical development from assumed chronological age and reproductive maturity.
Stage and maturity
Preserve the evidence separating chick, juvenile, immature and adult records.
- Which observed features support the assigned developmental stage? measurement
- Does the source establish chronological age or breeding maturity, or only a plumage category? boundary
Breeding-site use
Connect reproductive observations to a named species, site and season.
Breeding evidence and outcome
Separate presence near a possible nesting site from confirmed reproduction and measured success.
- What evidence establishes nesting, eggs, chicks or fledging at this site? measurement
- Which species, season and sampling method support reported breeding timing and success? provenance
- What observation method can answer the question while respecting documented nesting-site restrictions? action
Seasonal range and habitat Represent where member species breed, travel and occur at sea.
A family distribution assembled from observations can obscure seasonality, vagrancy and population differences.
Range evidence
Qualify geographic claims by species identity, date and occurrence role.
Seasonal occurrence meaning
Distinguish established seasonal range from isolated or uncertain records.
- Does this location represent breeding, passage, nonbreeding use or a vagrant observation? definition
- Which dated records or range assessment support native occurrence for the identified species? provenance
Habitat and connectivity
Connect terrestrial breeding locations with marine use only where evidence permits.
Breeding-to-marine links
Distinguish measured movements from inferred connections between breeding and offshore records.
- What tracking, resighting or survey evidence connects a breeding population to marine areas? provenance
- How were habitat use, seasonal occupancy and survey coverage measured? measurement
- Can the observed route be generalised beyond the tracked individuals and years? boundary
Feeding and ecological interactions Record how skuas obtain food and interact with prey, hosts and human food sources.
A reputation for food stealing must not substitute for evidence about diet or ecological effects.
Food acquisition
Separate feeding mechanisms and successful acquisition from pursuit alone.
Observed feeding mode
Classify each supported interaction as food theft, predation, scavenging or another observed mode.
- Was food actually obtained, and what evidence distinguishes theft from predation or scavenging? measurement
- Which prey or host taxon, skua species and seasonal context were identified? definition
Diet and impact
Evaluate dietary importance and ecological effects at the scale supported by sampling.
Interaction scale
Keep feeding observations distinct from estimates of dietary dependence or effects on other populations.
- Which method and sampling period support the estimated contribution of each food source? provenance
- Does evidence demonstrate an effect on the prey or host population, or only individual interactions? boundary
- What additional evidence is needed before changing access to discards or proposing intervention? action
Conservation and action Interpret assessments, pressures and possible actions without assigning a synthetic status to the entire family.
Species-level status and local conditions must remain distinguishable when deciding what may be done.
Assessment and trend
Attach conservation categories and population estimates to their assessed units.
Scoped conservation evidence
Record assessment year, geography and taxonomic treatment alongside status and trend.
- Which member species or population was assessed, in what year and under which assessment system? provenance
- Are reported counts individuals, breeding pairs or occupied territories, and how uncertain is the trend? measurement
- Does a taxonomic revision prevent direct comparison with an earlier assessment? boundary
Pressures and response
Connect documented local pressures to proportionate, authorised monitoring or management.
Evidence-led action
Require local evidence before attributing skua declines to disease, food change, disturbance or other pressures.
- What evidence links the suspected pressure to the affected species, population and period? provenance
- Which site rules, wildlife permissions and current biosecurity instructions govern the proposed activity? action
- What observable outcome would justify continuing, changing or stopping the response? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This is recalled knowledge, not a source-verified account; family authorship, date and exact database identifiers are omitted.
- Verify the chosen checklist's species limits and treatment of Stercorarius versus Catharacta; the kinds listed are not exhaustive.
- Conservation categories, assessment years, range boundaries and sexual size differences require species-specific verification.
- Which of these check these first hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Great skua (Stercorarius skua)
- South polar skua (Stercorarius maccormicki)
- Brown skua (Stercorarius antarcticus)
- Pomarine jaeger (Stercorarius pomarinus)
- Parasitic jaeger or Arctic skua (Stercorarius parasiticus)
- Long-tailed jaeger (Stercorarius longicaudus)
- Which of these kinds and varieties hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- Zoological scientific name - Stercorariidae - A family name, not a species binomial or an individual organism's identifier.
- GBIF taxon key - Numeric taxon identifier - The exact key and taxonomic treatment require verification.
- NCBI Taxonomy ID - Numeric taxon identifier - The exact family identifier requires verification.
- Which of these identifiers and schemes hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
Standards and regulation
Recalled without web access and unsourced; every item is a lead to verify.
- The International Code of Zoological Nomenclature, maintained by the International Commission on Zoological Nomenclature, governs zoological names, including family-group names.
- The IUCN Red List Categories and Criteria provide a framework for assessing extinction risk; assessments must be associated with the assessed taxon and date.
- Which of these standards and regulation hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Classification and identification in ornithology and biodiversity records.
- Research on kleptoparasitism, predation and seabird food webs.
- Tracking studies of long-distance migration and marine habitat use.
- Monitoring breeding populations and reproductive success.
- Which of these real-world use hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Applying one species' conservation status to the entire family.
- Confusing immature plumages, colour morphs or similar species during identification.
- Treating changes in genus placement as evidence of distinct biological entities.
- Disturbing breeding colonies; adults may make defensive aerial attacks near nests.
- Which of these failure modes and hazards hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- North American usage commonly calls the three smaller species jaegers; British usage calls them skuas.
- Breeding ranges differ among species, spanning northern high latitudes and southern subantarctic or Antarctic regions.
- Many populations migrate far from breeding grounds and spend substantial periods at sea.
- Which of these regional variation hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- Stercorarius - A genus within Stercorariidae; the family and genus are different taxonomic ranks even when a classification places all living members in this genus.
- Laridae - A separate charadriiform family containing gulls and, in widely used classifications, terns and skimmers.
- Catharacta - A genus name used in some classifications for the larger skuas, rather than a separate family.
- A skua population - A geographically or reproductively delimited group of organisms; Stercorariidae is a family-level taxon encompassing multiple species and populations.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of Stercorariidae this model covers, and on what evidence? provenance
What the second pass must settle
- Which taxonomic checklist and version should govern membership, species limits and historical Catharacta mappings?
- What are the verified family-name authority and date, and the matching GBIF and NCBI taxonomy identifiers?
- Which sourced field characters reliably distinguish Stercorariidae from gulls and terns across juvenile, adult and moulting plumages?
- Which life-history, sexual-dimorphism and seasonal-range statements are sufficiently supported across members to summarise at family level?
- What are the latest species-specific IUCN assessment years, categories and regional trends, and where are monitoring gaps too large to judge change?