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prosecution is strongly needed (Nellemann
et al.
, 2011). This also
includes better regulation of fencing and managing the expand-
ing livestock and cropland with specific reference to protecting
wildlife migrations and seasonal habitat to avoid further declines
in wildlife populations (Ogutu
et al.
, 2011).
The effect of roads, expanding agriculture and livestock, along
with increased poaching can also be observed in South America,
such as on the wild camelids in the steppe, deserts and Andean
foothills of Argentina and Chile. Guanacos (
Lama guanicoe
) and
vicunãs (
Vicugna vicugna
) have lost 40–75 per cent of their rang-
es, and probably dropped at least 90 per cent in their numbers
over the last centuries (Cajal, 1991; Franklin
et al.
, 1997). Only a
fraction, probably less than 3 per cent of the guanaco and some
34 per cent of that of vicunãs are in protected areas (Donadio
and Buskirk, 2006). Also these species often avoid areas with
expanding livestock and have been heavily exposed to poaching.
While roads or railways rarely result in complete physical block-
age, there is ample evidence and documentation that such in-
frastructure slows, delays or reduces the frequency of crossings
substantially, increases risk of predation or poaching, causes
expansion in agriculture along road corridors and subsequently
habitat loss resulting in declines in migratory populations over
time (UNEP, 2001; Bolger
et al.
, 2008; Vistnes and Nellemann,
2009), thus impacting entire ecological networks involving a
range of species.
Also here, international collaboration on enforcement as well
as removal of barriers is critical. Indeed, migrations and habi-
tat can sometimes even be restored if barriers to migrations,
such as fences or infrastructure, are removed (Bartlam-Brooks,
2011). This even accounts for removal of trails or roads or hous-
ing (Nellemann
et al.
, 2010). In a study in Northern Botswana,
a fence constructed in 1968 persisted up to 2004, and effec-
tively hindered migration of the plains zebra (
Equus burchelli
antiquorum
) between the Okavango Delta and Makgadikgadi
grasslands (a round-trip distance of 588 km), revealed that only
after four years some zebra had already reinstated this migra-
tion (Bartlam-Brooks, 2011).