A Video Surveillance System to Monitor Breeding Colonies of Common Terns (Sterna Hirundo)
Summary
This paper describes a protocol that uses a remote video monitoring surveillance system to continuously monitor breeding colonies of ground-nesting waterbirds. The system includes five cameras monitoring individual nests and one camera monitoring the colony as a whole, and is powered by car batteries that are recharged via solar panels.
Abstract
Many waterbird populations have faced declines over the last century, including the common tern (Sterna hirundo), a waterbird species with a widespread breeding distribution, that has been recently listed as endangered in some habitats of its range. Waterbird monitoring programs exist to track populations through time; however, some of the more intensive approaches require entering colonies and can be disruptive to nesting populations. This paper describes a protocol that utilizes a minimally invasive surveillance system to continuously monitor common tern nesting behavior in typical ground-nesting colonies. The video monitoring system utilizes wireless cameras focused on individual nests as well as over the colony as a whole, and allows for observation without entering the colony. The video system is powered with several 12 V car batteries that are continuously recharged using solar panels. Footage is recorded using a digital video recorder (DVR) connected to a hard drive, which can be replaced when full. The DVR may be placed outside of the colony to reduce disturbance. In this study, 3,624 h of footage recorded over 63 days in weather conditions ranging from 12.8 °C to 35.0 °C produced 3,006 h (83%) of usable behavioral data. The types of data retrieved from the recorded video can vary; we used it to detect external disturbances and measure nesting behavior during incubation. Although the protocol detailed here was designed for ground-nesting waterbirds, the principal system could easily be modified to accommodate alternative scenarios, such as colonial arboreal nesting species, making it widely applicable to a variety of research needs.
Introduction
Common terns (Sterna hirundo, hereafter COTE), a waterbird species with a widespread breeding distribution, have become a flagship example of the need for conservation and monitoring programs1. Once harvested to near extirpation for the millinery trade, federal legislation in the 1900s enabled populations to rebound. However, declining population trends in the Chesapeake Bay have prompted increased concern over COTE, in addition to many other waterbirds2. COTE are currently listed as a Maryland state endangered species due to reductions in both breeding numbers and active breeding colonies3. Stressors including flooding and washouts of breeding sites4,5,6, anthropogenic disturbance, competition/predation with gulls7,8, and predation by great horned owls (Bubo virginianus) and red foxes (Vulpes vulpes)9,10, are believed to have contributed to current population declines; however, the relative contributions of individual stressors are not known. Understanding stressors associated with different stages of the breeding cycle, such as incubation, post-hatch, and fledging success are important but can be intensive and include frequent surveys that require entry into the nesting colony11. Such monitoring techniques can be disruptive to tern populations, and in some cases may result in nest abandonment and/or reductions in reproductive success12,13,14.
While the impact of researchers on common terns is well documented, intensive monitoring can impact a number of additional ground-nesting colonial species, such as short tailed shearwaters (Puffinus tenuirostris)15, common eiders (Somateria mollissima)16, black skimmers (Rynchops niger)17, and Fiordland crested penguins (Eudyptes pachyrhynchus)18. For instance, a study on short tailed shearwaters found that monitoring intensity had an inverse relationship on hatching success, and can exacerbate population declines. These examples illustrate the increasing need to reduce disturbance while maintaining comprehensive monitoring programs. With the video system outlined in this paper, we aimed to obtain information on nest attentiveness and observation of predators in a manner that would reduce the physical presence of humans within the colony.
Our study was located at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island (38°46′01″N, 76°22′54″W, hereafter Poplar Island), one of the few known nesting sites for COTE in Maryland. Ongoing monitoring programs on Poplar Island have identified consistent nesting by COTE, albeit with variable levels of success depending on presence of avian or mammalian predators19,20. Due to these factors, Poplar Island was identified as an ideal location to conduct this study.
While the ability to monitor waterbird populations with video technology has clear benefits to the species under observation21,22, a number of technical considerations must be taken into account when implementing such an approach. For instance, video resolution must be sufficient to identify items of interest to the researcher, such as food items, nest markings, or colored leg bands for individual identification. Additionally, the physical components must be durable enough to withstand both weather events and wildlife interactions. Wireless security cameras were chosen due to their high definition picture quality, color display with wireless and infrared capabilities, outdoor durability, and overall cost effectiveness23.
The objective of this study was to design a video monitoring system that would allow for the remote observation of a ground-nesting colonial species while causing minimal disturbance to those individuals and the colony. This paper outlines the specific video system used to collect data.
Protocol
Representative Results
Discussion
Monitoring waterbirds can be disruptive, and investigator disturbance while monitoring waterbirds has been linked to nest abandonment and decreases in reproductive success12,13,14. The protocol presented here offers a minimally invasive monitoring approach that allows researchers to establish and document the nesting behavior of ground-nesting waterbirds through continuous video footage.
Because this …
Declarações
The authors have nothing to disclose.
Acknowledgements
All data reported in this manuscript were collected in accordance with protocol approved by the Patuxent Wildlife Research Center Animal Care and Use Committee. This project was funded by the Maryland Department of Natural Resources and supported by the USGS Ecosystems Mission Area. Video production was funded by The Chesapeake Bay Trust and Friends of Patuxent. We would like to thank the U.S. Army Corps of Engineers, Maryland Environmental Service, and Maryland Department of Transportation Maryland Port Administration for general logistical support and allowing video filming on site. We would like to acknowledge Dr. Bill Bowerman and Dr. Daniel Gruner from the University of Maryland for their input into system design and implementation. We would also like to acknowledge Bill Schultz, Kaitlyn Reintsma and Katie DeVoss for their help in troubleshooting and in field set-up in summer 2017. Finally, we would to thank Michael Glow (internal review) and anonymous reviewers for their input. The use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Materials
| Morningstar SS-20L-12V (2) | Morningstar Corporation | 3680192 | Charge controller |
| Renogy 100 W 12V Panel (4) | Renogy | RNG-100D | Solar panel |
| LOREX LW3211 (6) | Lorex | LW3211-2PK | Wireless camera with receivers |
| Sawhorse (4) | HDX | SH106 | |
| LOREX DV7082 | Lorex | DV7082W | 8ch 1080p HD DVR; Comes with computer mouse |
| 12V dry cell Absorbent Glass Mat (AGM) car batteries (6) | Optima | DS46B24R | |
| TCT LCD color monitor | Kuman | X0013XAI51 | Mini display monitor |
| 22 in. display monitor | Dell | S2218H | For office |
| 18 gallon plastic bin (2) | Sterilite | 1446 | Plastic container |
| Black copper insulated 10 AWG wire | Southwire | 22973257 | Black electrical wire |
| Red copper insulated 10 AWG wire | Southwire | 37113803 | Red electrical wire |
| 3/8 in. ring terminals | Autocraft | 85417 | |
| 5/16 in. ring terminals | AutoCraft | 85445 | |
| Winged wire connectors (red) | Commercial Electric | 775304 | Connector is large enough to accommodate 3 10AWG wires inside |
| 12V male DC adapter (2) | Avue | 162537 | |
| Male DC 2.1 x 5.5 mm power plugs for CCTV (4) | WinBook | 231001 | |
| Four port DC power splitters, 1 female to 4 | ClearView | PWRSPIDER4 | |
| 1.5 ft. wooden board (5) | Home Depot | 461443 | |
| 5 ft. wooden board | Vigoro | RC 85N | |
| 1/4 in. x 2 in. eye bolt (8) | Everbilt | 816721 | |
| 5/16 in. hex nuts (16) | Everbilt | 804886 | |
| 5/16 in. washers (16) | Everbilt | 807220 | |
| SAE size 6 stainless steel clamps (8) | Everbilt | 670655E | |
| 60ft. BNC extension cables (6) | WinBook | 432377 | |
| 2 ft. x 4 ft. wooden plywood | Home Depot | 1502104 | Cut to 1 ft. x 2 ft. |
| 5 ft. metal rebar (8) | Weyerhaeuser | 35616 | |
| Bungee cord (2) | HDX | 56128 | For securing lid |
| 15 ft. x 3/4 in. sticky back tape | Velcro | 239540 | |
| Duct tape | Duck | 392875 | |
| Permanent Marker | Sharpie | 35010 | |
| 1/4 in. x 400 ft. white diamond braid nylon rope | Everbilt | 72716 | |
| Weatherproof electrical tape | Scotch | 6143-BA-10 | |
| Schumacher 6A 12V automatic battery charger/ Carquest battery charger 8A | Schumacher/ Carquest | SP6/ CQ-80CR | Two possible car battery chargers |
| 6 in. nails (14) | Grip-Rite | 60HGC | |
| 18 Volt 1/2 in. Drill-Driver | Ryobi | P208B | Drill |
| 25 watt standard duty soldering iron | Weller | SP25NKUS | Soldering iron |
| Leaded rosin core solder | Bernzomatic | 354123 | Solder |
| Wire cutter | Stanley | 84-199 | |
| Screwdriver | Husky | 146340142 | Came from 14 piece set of Phillips and flathead drivers |
| 15 in. aggressive tooth saw | Home Depot | 122SS159 | |
| Rubber mallet | HDX | 31030 | |
| Post driver | Everbilt | 901147EB |
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- . LW3211 series specs Available from: https://www.lorextechnology.com/downloads/wireless-security-cameras/LW3211-Series/LW3211_Series_Spec_R1.pdf (2017)
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- . 720P Wireless digital security camera LW3211 series quick start guide Available from: https://www.lorextechnology.com/downloads/wireless-security-cameras/LW3211-Series/LW3211_SERIES_QSG_EN_R1.pdf (2017)
