Remote sensing image data and automated analysis to describe marine bird distributions and abundances

Groom, Geoff; Stjernholm, Michael; Nielsen, Rasmus Due; Fleetwood, Andrew J.; Petersen, Ib Krag

doi:10.1016/j.ecoinf.2012.12.001

Cited by 45 publications

(63 citation statements)

References 27 publications

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“…Moreover, image detectors did not reliably identify the number of cormorants, due to rapidly changing light conditions and glare from the ocean. Although building an effective image recognizer was beyond the scope of our research, using algorithms to automatically identify the abundance of individuals across large numbers of photographs holds great promise for expanding the extent of video analysis (Kelly 2001, Speed et al 2007, Groom et al 2013). …”

Section: Discussionmentioning

confidence: 99%

Visitor noise at a nesting colony alters the behavior of a coastal seabird

Buxton¹,

Galvan²,

McKenna³

et al. 2017

Mar. Ecol. Prog. Ser.

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Exposure to park visitors can disrupt animal behavior. Management strategies often aim to eliminate direct human disturbance; however, elevated visitor noise levels may remain. Coastal seabird colonies frequently overlap with scenic locations, resulting in high visitor noise and potentially altered behavior, habitat use, and fitness. We examine the impact of visitor noise on Brandt's cormorants Phalacrocorax penicillatus at Alcatraz Island, an important nesting site and one of California's most visited attractions. We used paired acoustic and video recorders to investigate the relationship between visitor noise levels and the behavior and relative abundance of cormorants in colonies adjacent to and far from a heavily visited building. Visitors were not visible from the cormorant colonies. At cormorant colonies adjacent to the visited building, disturbance-related behaviors increased with visitor noise. Conversely, there was no relationship between behavior and visitor noise in colonies far from the visited building. Cormorant disturbance behavior increased and abundance decreased when gulls were present at colonies adjacent to the visited building, whereas there was no relationship between gulls and behavior or abundance at colonies far from the visited building. Our results suggest that visitor noise alters cormorant behavior and decreases colony attendance, particularly in the presence of nest predating gulls. Visitor noise can be mitigated by implementing quiet zones, offering a cost-effective method of reducing disturbance to nesting cormorants. Understanding the relationship between altered behavior and demographic parameters is vital to conserving these coastal species and mitigating the effects from continued increases in recreation activity.

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Section: Discussionmentioning

confidence: 99%

Visitor noise at a nesting colony alters the behavior of a coastal seabird

Buxton¹,

Galvan²,

McKenna³

et al. 2017

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

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“…According to the assumptions made in (Groom, 2013), the goal for automated detection of sea birds is to filter the localisations of possible bird candidates in a way, that under-estimation should be avoided or minimized, while over-estimation might be accepted to a certain degree. Thus, our task was to find a set of filter criterions and parameters to balance a trade-off between those two antagonal requirements.…”

Section: Filtering Accuracymentioning

confidence: 99%

“…Overviews on the early Approaches are given in (Allen, 1991) and (Groom, 2013). The utilized approaches range from simple thresholding (Bajzak, 1990) and template matching (Allen, 1991) up to the simulated annealing of spatial models (namely Markov point processes; Descamps, 2011) and Object-based Image Analysis (OBIA) (Groom, 2013). Yet, a fully automated process is far out of sight.…”

Section: Introductionmentioning

confidence: 99%

Automatic Sea Bird Detection From High Resolution Aerial Imagery

Mader¹,

Grenzdörffer²

2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Great efforts are presently taken in the scientific community to develop computerized and (fully) automated image processing methods allowing for an efficient and automatic monitoring of sea birds and marine mammals in ever-growing amounts of aerial imagery. Currently the major part of the processing, however, is still conducted by especially trained professionals, visually examining the images and detecting and classifying the requested subjects. This is a very tedious task, particularly when the rate of void images regularly exceeds the mark of 90%. In the content of this contribution we will present our work aiming to support the processing of aerial images by modern methods from the field of image processing. We will especially focus on the combination of local, region-based feature detection and piecewise global image segmentation for automatic detection of different sea bird species. Large image dimensions resulting from the use of medium and large-format digital cameras in aerial surveys inhibit the applicability of image processing methods based on global operations. In order to efficiently handle those image sizes and to nevertheless take advantage of globally operating segmentation algorithms, we will describe the combined usage of a simple performant feature detector based on local operations on the original image with a complex global segmentation algorithm operating on extracted subimages. The resulting exact segmentation of possible candidates then serves as a basis for the determination of feature vectors for subsequent elimination of false candidates and for classification tasks.

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“…Groom et al, 2013). The gyro-static camera platform is connected with a computer system that triggers shutter release, stores the incoming image files and, at the same time, operates the flight management system (AeroTopoL) and the logging of geographic position and altitude from the GNSS-INS sensors (Kemper, 2012).…”

Section: Camera Technologymentioning

confidence: 99%

Monitoring Seabirds and Marine Mammals by Georeferenced Aerial Photography

Kemper¹,

Weidauer²,

Coppack³

2016

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:The assessment of anthropogenic impacts on the marine environment is challenged by the accessibility, accuracy and validity of biogeographical information. Offshore wind farm projects require large-scale ecological surveys before, during and after construction, in order to assess potential effects on the distribution and abundance of protected species. The robustness of site-specific population estimates depends largely on the extent and design of spatial coverage and the accuracy of the applied census technique. Standard environmental assessment studies in Germany have so far included aerial visual surveys to evaluate potential impacts of offshore wind farms on seabirds and marine mammals. However, low flight altitudes, necessary for the visual classification of species, disturb sensitive bird species and also hold significant safety risks for the observers. Thus, aerial surveys based on high-resolution digital imagery, which can be carried out at higher (safer) flight altitudes (beyond the rotor-swept zone of the wind turbines) have become a mandatory requirement, technically solving the problem of distant-related observation bias. A purpose-assembled imagery system including medium-format cameras in conjunction with a dedicated geo-positioning platform delivers series of orthogonal digital images that meet the current technical requirements of authorities for surveying marine wildlife at a comparatively low cost. At a flight altitude of 425 m, a focal length of 110 mm, implemented forward motion compensation (FMC) and exposure times ranging between 1/1600 and 1/1000 s, the twin-camera system generates high quality 16 bit RGB images with a ground sampling distance (GSD) of 2 cm and an image footprint of 155 x 410 m. The image files are readily transferrable to a GIS environment for further editing, taking overlapping image areas and areas affected by glare into account. The imagery can be routinely screened by the human eye guided by purpose-programmed software to distinguish biological from non-biological signals. Each detected seabird or marine mammal signal is identified to species level or assigned to a species group and automatically saved into a geo-database for subsequent quality assurance, geo-statistical analyses and data export to third-party users. The relative size of a detected object can be accurately measured which provides key information for species-identification. During the development and testing of this system until 2015, more than 40 surveys have produced around 500.000 digital aerial images, of which some were taken in specially protected areas (SPA) of the Baltic Sea and thus include a wide range of relevant species. Here, we present the technical principles of this comparatively new survey approach and discuss the key methodological challenges related to optimizing survey design and workflow in view of the pending regulatory requirements for effective environmental impact assessments.

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Remote sensing image data and automated analysis to describe marine bird distributions and abundances

Cited by 45 publications

References 27 publications

Visitor noise at a nesting colony alters the behavior of a coastal seabird

Visitor noise at a nesting colony alters the behavior of a coastal seabird

Automatic Sea Bird Detection From High Resolution Aerial Imagery

Monitoring Seabirds and Marine Mammals by Georeferenced Aerial Photography

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