Various techniques for bird monitoring already exist and some of them are more time-consuming and expensive than others. Direct observation is the simplest and oldest technique and may differentiate migratory birds based on size, color, song and flight characteristics [14]. Slight modifications allow also Sorafenib Tosylate mechanism night observations (moon-watching Inhibitors,Modulators,Libraries technique [14,15]) by applying terrestrial vertical light beam or ceilometer techniques [16]. The use of passive infrared cameras (measuring avian body heat) allows cloudy night observation and reduces Inhibitors,Modulators,Libraries disturbances due to artificial light [17,18]. Capture-recapture techniques also can provide valuable information about bird migration [14,19] but less than 1% of the non-hunted species are ever recorded again [14]. Radio tracking or telemetry is another method to monitor birds [20,21].

A small radio transmitter is attached to the bird and sends a periodic beep signal which is tracked down. Birds, however, with an attached device have a significantly lower survival rate. More recently this technique evolved to GPS-tracking which rules out some of the limitations of radio tracking [12,22]. Another approach for bird detection is Inhibitors,Modulators,Libraries the use of acoustic based technology to identify bird specific signatures such as drums from woodpeckers [23]. Also radar based monitoring technology is used for bird detection, although the coarse spatial resolution is a limiting factor [24].Novel tools for bird monitoring are using distance retrieval from stereo vision and motion detection.

Stereo vision is used in several domains where depth is essential, for instance in robot-computer Inhibitors,Modulators,Libraries vision [25], traffic flow control [26] or in ecological studies such as fish size measuring [27,28] or to rediscover extinct birds such as the Ivory-billed Woodpecker (Campephilus principalis) in the US [23]. Most methods are based on the knowledge of the disparity and the angle between the cameras and the object [28]. Background subtraction is a Carfilzomib common approach to detect moving objects in a sequence of images or videos. It consists of comparing each frame with background model and retaining the foreground pixels that differ significantly from the background. This technique is often implemented in computer vision applications, video surveillances, traffic monitoring and human tracking [30�C32].In this study the potential of permanent cameras such as webcams for bird detection is analyzed.

Webcams are low-cost cameras, can be adapted to be robust to weather sellckchem conditions, and have the ability of remotely-control and unsupervised operation capabilities. As such, they can be used as first analysis tool for tracking moving objects. With this demonstration study, we aim to sensitize readers on the potentials of webcams for a variety of applications of monitoring moving objects.