Greenland white-fronted geese Anser albifrons flavirostris, a protected species in Scotland, breeds in western parts of Greenland and migrates via Iceland to over winter in parts of Ireland and Scotland. The global population has continued to decline since the late 1990s, falling from approximately 36,000 to 20,000 individuals. Consequently, they are a bird of conservation concern.
Based on experience, this species can be somewhat irregular in their use of roosting sites, with several factors influencing their choice: namely, distance associated with daytime foraging locations, the weather, and human disturbance etc. Recently, whilst undertaking a dawn Vantage Point survey over a Loch in Caithness, I observed a skein of 60+ White-Fronted geese fly into the site, in total darkness. I believe they had been roosting on a nearby Loch but were disturbed by gun shots, which I had heard some minutes earlier.
There are several Lochs within Caithness, which are known roosting sites for this species, several of which are afforded statutory protection (Special Protection Areas). However, I was interested to establish where else do they roost? So, I’m currently embarking on a study of some of the other Lochs within the county.
At my first study site, I was already aware that both Whooper swans Cygnus cygnus and Greylag geese Anser anser roost there, so the objective of the survey was simple, to establish the presence or not of roosting Greenland White-Fronted geese. As a means of furthering my investigation, I decided to deploy a single acoustic recorder, in a discrete location adjacent to the shoreline, the recorder was programmed to commence recording between one hour before sunset and one hour after sunrise and was left insitu for four consecutive nights.
Upon collecting the recorder and analysing the results, White-Fronted geese were indeed recorded, Figure 1) below depicts some of their vocalisations in the form of a sonogram; together with an audio file recorded during the deployment. For each recorded file the date and time is captured, as part of the meta data, this showed they did not arrive on the study site until the third evening.
Although this deployment was straightforward in its objective, the results more than adequately demonstrate the benefits of employing Bioacoustic monitoring, in a species-specific presence / absence survey. The simplicity of deploying one recorder, compared to the cost and manhours required if traditional survey methodologies were employed, to obtain the same results.
Figure1) Greenland White-Fronted Geese
Let's Listen.
In-addition to the turkey like calls of the White-Fronted Geese, you can also hear the whistling of a Wigeon and the trumpeting of a Whooper swan.
Figure 2) SkyLark Sonogram
Some species of birds; notably, the Skylark, possesses a very complex song structure, which is clearly demonstrated on the above sonogram. I have uploaded a soundscape, which I recorded on some coastal grassland near my house. The recording not only includes a Skylark but a Curlew for good measure.
In contrast, other species possess simple structures to their vocalisations, take for example the Reed Bunting, with its simple repetitive but rather mournful call.
Figure 3) Reed Bunting Sonogram
