Monitoring the Hatching Success of Gulls Laridae and Terns Sternidae: A Comparison of Ground and Drone Methods

Valle, Roberto G.; Scarton, Francesco

doi:10.3161/00016454ao2021.56.2.010

Cited by 9 publications

(8 citation statements)

References 51 publications

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“…Although similar effects have been noted many times elsewhere (Koffjberg et al ., 2016; Ritenour et al ., 2022) by traditional observation, i.e., repeated field surveys, the present study combined these with the use of a drone. This rapidly obtained reliable data with very little disturbance to the birds, as demonstrated on several occasions with terns, gulls and other species in the Northern Adriatic wetlands (Valle & Scarton, 2021a, b, c).…”

Section: Discussionmentioning

confidence: 70%

“…All apparently occupied nests (as defined by Steinkamp et al , 2003) were counted and the number of breeding pairs was assumed to be the same as the number of occupied nests. We used a small drone (DJI Mini 2) to count nesting pairs and to measure reproductive success at selected sites (after Valle & Scarton, 2021a, b). All data in the present study were obtained using drone imagery.…”

Section: Methodsmentioning

confidence: 99%

“…Maximal flight time was < 5 min. During the drone flight, a researcher observed the colony from afar so that possible predation of unattended clutches and/or chicks by aerial predators (such as Marsh Harriers Circus aeruginosus , Yellow-legged Gulls Larus michahellis or Eurasian Oystercatcher Haematopus ostralegus ; Valle & Scarton, 2021b) or kleptoparasites (such as Black-headed Gulls Larus ridibundus ; Dies & Dies, 2005) could be excluded. Drone counts were performed on a personal computer using the DotDotGoose count tool v. 1.3.0 (Ersts, 2019) on images taken directly in the field or from selected frames obtained from videos automatically stitched together using ICE (Microsoft's Image Composite Editor, release 2.0; www.microsoft.com).…”

Section: Methodsmentioning

confidence: 99%

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One Thousand Nesting Pairs Packed into One Hundred Square Metres: The Sad Story of the Sandwich Terns Thalasseus Sandvicensis of the Venice Lagoon

Valle¹,

Scarton²

2023

Ardeola

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SummaryCoastal wetlands support many globally threatened seabird species and may be critical for their conservation. Sea level rise dramatically affects coastal tidal marshes, thus posing the greatest threat to the survival of many seabird species, including gulls and terns. Sandwich Terns Thalasseus sandvicensis are particularly vulnerable to this threat. Although they breed in a wide range of habitats they chiefly nest close to water, just above the tideline. Here, we describe the particular vulnerability of the entire Sandwich Tern breeding population of the Venice Lagoon. Three colonies were found early in the 2022 breeding season, two of them on artificial habitat: on a small dredge island (0.01ha; 0.70m above sea level) in the Northern Lagoon and on an islet (0.01ha, elevation 0.5m a.s.l.) formed by bricks of a collapsed old building in the Southern Lagoon. The third colony was on a natural marsh island (1.50ha, 0.40m a.s.l.). These colonies hosted respectively 150, 369 and 1,100 pairs. In total, 1,111 out of 1,619 nests (68.6%) were flooded early in the season, with marked differences between sites; nest losses ranged from 86% on the brick island through 69% on the marsh island to 0% on the dredge island. The terns laid 1,043 replacement clutches, exclusively on the dredge island, joining the birds on this safe site. Overall, 795 chicks fledged (0.30 per breeding attempt) over the whole breeding season, with extreme differences between colony sites. Productivity ranged from zero fledglings per breeding attempt on the marsh island through 0.14 on the brick island to 0.75 on the dredge island. Artificial sites such as dredge islands may offer safe nesting sites and enable high productivity for Sandwich Tern when compared to saltmarsh islets. Given the probability of future sea level rises, a long-term management plan for these artificial sites is urgently needed.—Valle, R.G. & Scarton, F. (2023). One thousand nesting pairs packed into one hundred square metres: the sad story of the Sandwich Terns Thalasseus sandvicensis of the Venice Lagoon. Ardeola, 70: 89-103.

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Section: Discussionmentioning

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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One Thousand Nesting Pairs Packed into One Hundred Square Metres: The Sad Story of the Sandwich Terns Thalasseus Sandvicensis of the Venice Lagoon

Valle¹,

Scarton²

2023

Ardeola

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“…The risk of disturbance and collisions from drones should thus be placed within the context of the risks and inefficiencies of on‐foot monitoring. For example, monitoring tern nests with drones is 2.89 times faster than on‐foot observations (based on information provided by Valle & Scarton, 2021 ). Also, if Stork ( Ciconia Ciconia ) parents leave their nests during monitoring events, their return time to the nest is shorter when monitored with drones than on‐foot monitoring (Zbyryt et al., 2021 ), further emphasising the reduction in stress from drone monitoring.…”

Section: Discussionmentioning

confidence: 99%

Drones as a tool to study and monitor endangered Grey Crowned Cranes (Balearica regulorum): Behavioural responses and recommended guidelines

Demmer,

McIntyre

2024

Ecology and Evolution

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Crane populations are declining worldwide, with anthropogenically exacerbated habitat loss emerging as the primary causal threat. The endangered Grey Crowned Crane (Balearica regulorum) is the least studied of the three crane species that reside in southern Africa. This data paucity hinders essential conservation planning and is primarily due to ineffective monitoring methods and this species' use of inaccessible habitats. In this study, we compared the behavioural responses of different Grey Crowned Crane social groupings to traditional on‐foot monitoring methods and the pioneering use of drones. Grey Crowned Cranes demonstrated a lower tolerance for on‐foot monitoring approaches, allowing closer monitoring proximity with drones (22.72 (95% confidence intervals ‐ 13.75, 37.52) m) than on‐foot methods (97.59 (86.13, 110.59) m) before displaying evasive behaviours. The behavioural response of flocks was minimal at flight heights above 50 m, whilst larger flocks were more likely to display evasive behaviours in response to monitoring by either method. Families displayed the least evasive behaviours to lower flights, whereas nesting birds were sensitive to the angles of drone approaches. Altogether, our findings confirm the usefulness of drones for monitoring wetland‐nesting species and provide valuable species‐specific guidelines for monitoring Grey Crowned Cranes. However, we caution future studies on wetland breeding birds to develop species‐specific protocols before implementing drone methodologies.

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“…Drone flights were performed according to current recommendations to minimize disturbance to birds (Hodgson & Koh 2016). The drone was launched at least at 150 m from the colony, it climbed vertically to 70 m above ground level (AGL) and then approached the colony, using a lawn mower flight pattern (Valle & Scarton 2021b) to reach a point above the colony at 20–70 m AGL, where it hovered to take imagery at an angle as vertical as possible in order to minimize variations in subject size and shape (Chabot & Francis 2016). Nests were searched and monitored flying at elevations above ground level higher than the agitation distance for Ardeidae in general and in particular for the studied species (10 m; Valle & Scarton 2018).…”

Section: Methodsmentioning

confidence: 99%

Faster and Better: Comparison between Traditional and Drone Monitoring in a Cryptic Species, the Purple Heron Ardea purpurea

Corregidor-Castro

Scarton

Panzarin³

et al. 2023

Acta Ornithologica

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Monitoring waterbirds is fundamental to understand the health status of wetland habitats. However, this monitoring has to be conducted by means of reliable data collection that can provide accurate information on population trends. Usually, waterbird monitoring is difficult, as nesting grounds are usually located in inaccessible reedbed, and by eye detection of cryptic species is hard. Drones have the capacity to overcome most of these problems, as they can provide with an aerial view of places otherwise unreachable, while reducing the disturbance and time spent in the field. The present study aims to compare the accuracy, disturbance levels, and managerial efficiency between ground (traditional) and drone counts of a cryptic species, the Purple Heron Ardea purpurea. Traditional monitoring methods were only capable of detecting 35% of the nesting pairs detected by the drone surveys (8.0 ± 11.8 versus 22.9 ± 38.2 nesting pairs in ground and drone surveys, respectively). Consequently, colony size estimates between methods showed poor agreement, to the point that traditional methods missed colonies otherwise detected by the drone. No apparent negative effects on nesting pairs where found when flying the drone. In addition, mean time spent to survey breeding sites with a drone was far less than with the traditional approach, down to a six-fold time reduction. This reduction, together with a lack of disturbance observed when conducting the drone monitoring, and an increasing monitoring precision and accuracy, supports the use of drones as the least invasive option for studies on population monitoring on hardly accessible sites.

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Monitoring the Hatching Success of Gulls Laridae and Terns Sternidae: A Comparison of Ground and Drone Methods

Cited by 9 publications

References 51 publications

One Thousand Nesting Pairs Packed into One Hundred Square Metres: The Sad Story of the Sandwich Terns Thalasseus Sandvicensis of the Venice Lagoon

One Thousand Nesting Pairs Packed into One Hundred Square Metres: The Sad Story of the Sandwich Terns Thalasseus Sandvicensis of the Venice Lagoon

Drones as a tool to study and monitor endangered Grey Crowned Cranes (Balearica regulorum): Behavioural responses and recommended guidelines

Faster and Better: Comparison between Traditional and Drone Monitoring in a Cryptic Species, the Purple Heron Ardea purpurea

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