Sergey Dereliev

Very large breeding range: S Europe up to E Asia, Africa, southern part of N America to southern S America (BirdLife International 2021). Behaviour from resident to migratory. European birds spend the winter from tropical to S Africa, though a progressively higher proportion of them are now seen overwintering in S Europe (but these birds may comprise less than 1% of the European population).

Season of assessment

B

Population trendStable
Population size
(min-max, best estimate)		114000-169000,137000
Red List categoryLC
Franks, S., Fiedler, W., Arizaga, J., Jiguet, F., Nikolov, B., van der Jeugd, Ambrosini, R, Aizpurua, O., Bairlein, F., Clark, J., Fattorini, N, Hammond, M., Higgins, D, Levering, H., Skellorn, W., Spina, F, Thorup, K. Walker, J., Woodward, I. and Baillie, S.R. (1) (2022) Online Atlas of the movements of European bird populations. https://migrationatlas.org EURING/CMS (1) Principal investigator
Map

Overall Connectivity for Black-crowned Night Heron

In Europe, it is a long-distance migrant spending the winter across the main wetlands in the Sahel (Zwarts et al. 2009). The graphics reveal two main kind of movements: (1) After-breeding dispersal, which seems to be random, and (2) migration to Africa, though some birds overwinter in Europe (e.g., some ringed in Jun in SW Europe or C Europe overwinter in the Atlantic coast). Populations from W Europe tend to overwinter in regions further to the W but yet there is a very high overlap of populations in winter. C European birds seem to show the widest distribution range in winter, with a couple of recoveries in Russia and the E Mediterranean area. Overall, the degree of connectivity seems to be small. Recoveries in spring in SE Europe of herons ringed in SW Europe are not rare, suggesting what it could be high genetic flow between populations.

Recoveries by Condition for Black-crowned Night Heron

Both in Europe and Africa, most recoveries are due to birds found dead, with more or less similar proportions between those dead by shot and those found sick/wounded.  An also remarkable proportion of recoveries is associated to unknown causes, but most of these might be due to birds found dead. The number of recoveries of birds seen alive (e.g., identified from leg ring(s)) is relatively marginal in the data set.

Annual Movements for Black-crowned Night Heron

Migration starts mostly in Aug, with substantial movements by Sep onwards. Recoveries in C Africa found from Jan to Dec, but note however that some birds seem to summer in Africa. Most birds would reach C Africa in Sep or later and would leave this region before Mar. The distribution range of birds overwintering in Europe is wide, from SW to SW Europe, also reaching the N Sea and UK; again, high overlap between regions of origin. Differential reporting rate of ring-recovery data in Europe/Africa probably provides an over-representation of those birds spending the winter in Europe (recoveries from Nov to Feb).

Connectivity by Month by Region for Black-crowned Night Heron

Movement patterns fairly similar among regions, so for details see the Annual movements’ section.

Juan Arizaga

References

Statistics Map
N records N individuals N recoveries
Mapped data*
Total available data
*Mapped data include only distant (>= 50 km) recoveries
References Map
BirdLife International2021 . Species factsheet: Nyctycorax nyctycorax.
Zwarts, L., Bijlsma, R. G., van der Kamp, J., Wymenga, E. 2009 . Living on the edge: Wetlands and birds in a changing Sahel. KNNV Publishing, Zeist

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