• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
SACC. 2005 and updates. A classification of the bird species of South America. Available at: https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2022	Least Concern
2016	Near Threatened	A3c
2012	Near Threatened	A3c
2009	Least Concern
2008	Least Concern
2004	Least Concern
2000	Lower Risk/Least Concern
1994	Lower Risk/Near Threatened
1988	Threatened

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	7,800,000 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	-	-	-
Population trend	decreasing	-	suspected	2016-2028
Rate of change over the past 10 years/3 generations (longer of the two periods)	10-19%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	10-19%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	10-19%	-	-	-
Generation length	3.86 years	-	-	-

Population justification: The population size is not known. The species is considered to be scarce, but widespread and locally common or numerous; it may be easily overlooked (Martínez-Vilalta et al. 2020).

Trend justification: The species is suspected to be in decline as a consequence of habitat loss and local impacts of hunting. Over three generations (11.6 years), 6% of tree cover is lost within the range (Global Forest Watch 2021, using Hansen et al. [2013] data and methods disclosed therein). Given that the species is strictly dependent on forests near watercourses, the rate of population decline may be larger than the rate of tree cover loss due to the impacts of habitat fragmentation and degradation; moreover, hunting may additionally aggravate the rate of population decline. Therefore, the rate of population decline is tentatively placed in the band 10-19% over three generations.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Bolivia	extant	native	yes
Brazil	extant	native	yes
Colombia	extant	native	yes
Ecuador	extant	native	yes
French Guiana	extant	native	yes
Guyana	extant	native	yes
Peru	extant	native	yes
Suriname	extant	native	yes
Venezuela	extant	native	yes

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Mangrove Vegetation Above High Tide Level	suitable	resident
Forest	Subtropical/Tropical Swamp	major	resident
Wetlands (inland)	Permanent Freshwater Marshes/Pools (under 8ha)	major	resident
Wetlands (inland)	Permanent Rivers/Streams/Creeks (includes waterfalls)	major	resident
Altitude	0 - 500 m	Occasional altitudinal limits	(max) 800 m

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Livestock farming & ranching - Agro-industry grazing, ranching or farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Species mortality

Purpose	Scale
Food - human	subsistence, national

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Recommended citation
BirdLife International (2024) Species factsheet: Zigzag Heron Zebrilus undulatus. Downloaded from https://datazone.birdlife.org/species/factsheet/zigzag-heron-zebrilus-undulatus on 18/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 18/12/2024.