Bear habitats in Bulgaria are scattered in different parts of the country. A bear is never to meet its cousins living in another range, as this would involve passing near areas of human habitation, crossing motorways with cars and trucks streaking past, or dodging trains thundering down tracks. Thus, for example, Motorway Trakia bisects the migration route, cutting off any connection between the bear subpopulations in the Balkan range and the Rila-Rhodope mountains. This stands in the way of natural resettlement of animals from more densely populated areas with less food into other habitats where conditions are more favorable. Motorway builders should provide wooded overpasses with soundproof screens to allow wild animals to cross over to the other side; failing that, bears will need to be resettled artificially in order to keep the gene pool healthy.