The UN derives its data from satellite photography, taken in December each year, backed up by field visits to sample sites.

ECONOMIST: Coca and cocaine in the Andes

Officials will continue to investigate animal deaths where appropriate, carrying out field visits and collecting carcases for post mortem at the Veterinary Laboratories Agency.

BBC: 'Big cat' probe after sheep death in Pembrokeshire

This was followed by field visits by experts to assess the situation in the Dolo Ado refugee camp in the southeast of the country from 4 to 10 November and in the Fafen upper valley from 12 to 14 November ( see map).

UNESCO: Combating drought in the Horn of Africa

Lessons include in-school visits from local entrepreneurs and field trips to Junior Achievement centers where kids learn financial lessons such as opening a bank account.

WSJ: Making Young Kids Smarter About Finance

Each year, Hennessy visits four to five freshman dormitories to field questions.

NEWYORKER: Get Rich U.

Identify, communicate and organize visits to the Centre of leading experts in the field as well as young scientists from developing countries.

UNESCO: Vacancy : Senior Research Scientist (31/5/2011) (EU/TP/ITA/SC/0856 - (P4))

The course will combine presentations with practical examples, technical visits, as well as the application of service design and consumer touchpoints in the field to support and ensure successful biodiversity-based tourism product development.

UNESCO: Call for South East European applications to the Training course on Tourism and Biodiversity | United Nations Educational, Scientific and Cultural Organization