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Libro degLi AbstrAct
a cura di
Rosario Balestrieri
Gaia Bazzi
XX coNVegNo itALiANo di orNitoLogiA
126
Censusing purple herons breeding on inaccessible sites by drones: cutting corners or
the best thing since sliced bread?
EmilianoVerza1,FrancescoScarton2,LucioPanzarin3,RobertoG.Valle4
1Ass.Sagittaria
2SELCSoc.Coop.
3AssociazioneNaturalisticaSandonatese
4Rialto,SanPolo571,30125Venezia,Italia
Censusing breeding purple herons (Ardea purpurea) is hard, in view of the diculty to access the breeding
sites, to nd the highly camouaged nests and the need to avoid disturbing nesting birds. Drones are
increasingly used to census waterbirds, due to their capacity to overcome most of these problems.
The present study aims to compare eectiveness, managerial eciency, and safety for birds of drone-
conducted counts on 20 heronries of purple herons located in the coastal area (within 15 km from the
sea) of Veneto Region (NE Italy). In 2019, drone ights counted 16+25 heron pairs, versus a count of
8+18 from ground censuses (Wilcoxon signed-rank test, P < 0.01). Furthermore, during drone ights,
no nests were found on four sites believed to host eight purple heron pairs by ground counts, whilst 65
pairs were found on two newly found breeding sites. These values allowed for far better sensitivity and
specicity for drone surveys. As a consequence, the average coecient of agreement between methods
was “poor” (Cohen’s kappa = 0.18; T = 0.25; P = 0.02). Mean time spent to survey a heronry with a
drone was far less than with the traditional approach: 4+2 vs 27+10 min (Wilcoxon signed-rank test, P
< 0.001). Overall, 9.0 hours were spent on censusing the whole area by the traditional approach vs1.25
hours by the drone method (-86%). This corresponds to an expenditure of € 540 vs 75 € for traditional
vs drone approach. No apparent negative eects on nesting pairs or clutches were observed. Our study
shows that drone ights constitute the least invasive option for studies on the breeding biology of purple
herons nesting on inaccessible sites. Drone use improved the eectiveness of nest nding and reduced
disturbance to incubating birds. Integrating this new tool into the traditional ground approach would
allow researchers to more rapidly identify nests, simultaneously reducing costs.
La biologia riproduttiva della sterna zampenere in Italia
EmilianoVerza1,MarcelloGrussu2,FrancescoScarton3,RobertoG.Valle4
1AssociazioneCulturaleNaturalisticaSagittaria
2GruppoOrnitologicoSardo
3SELCSELCSoc.Coop.
4Rialto,571,30125Venezia
La sterna zampenere (Gelochelidonnilotica) era riportata nidicare in Italia con circa 550 coppie nel 2002,
distribuite principalmente nelle zone umide costiere della Romagna, della Puglia e della Sardegna.
Recentemente, la specie ha mostrato una chiara fase di espansione d’areale, colonizzando la parte veneta
del Delta del Po e la Laguna di Venezia. Vengono qui riassunte le conoscenze su alcuni aspetti della
biologia riproduttiva e sull’andamento numerico nel periodo 2001-2018 delle popolazioni nidicanti
in alcune zone umide italiane (laguna di Venezia, Delta del Po veneto, zone umide della Sardegna
occidentale e meridionale). La sterna zampenere ha evidenziato un aumento marcato in laguna di
Venezia e nel Delta del Po (da circa 250 coppie a oltre 900 nel periodo 2015-2018). Al contrario, la
popolazione nidicante in Sardegna ha evidenziato una fase di decrescita tra il 2015 ed il 2018, pur
nel contesto di un generale incremento sul lungo periodo. I siti di nidicazione più frequentemente
utilizzati si confermano essere isolotti, argini, dossi, costituiti da limi e argille consolidate, spesso di
recente realizzazione da parte dell’uomo. Il successo riproduttivo stimato per la sterna zampenere nei
siti di monitoraggio appare adeguato al mantenimento della popolazione nidicante.
