The results shown in this report demonstrate a strong correlation between raptor abundance and dune height and can therefore infer that it supports the hypothesis being tested.
A primary mechanism for why raptors use taller dunes may be for efficient flight patterns. Previous literature has focused on avian scavengers and their physical morphologies, for the adaptation of soaring flight rather than flapping. They utilise strong winds (thermals) in high mountain ranges to aid in soaring patterns (Ruxton & Houston 2004). In addition to this, other types of raptors make use of orographic lift components (Bohrer et al.
2012). A comparison can be made to the raptors recorded in this study in that they exploit the higher dunes in the same manner, to minimise energy costs.
Another mechanism that raptors use higher dunes is for nesting and perching sites. Previous observations of white-bellied sea eagles (Haliaeetus leucogaster) have recorded nests located high up within tall trees (18-28m). Thirty percent of nests were recorded at the highest elevation between 31-100m (O’Donnell & Debus 2012).
Raptors documented in the present study may follow the same nest site selection while still being closely located to their dietary resources. Higher dunes could also provide larger territory areas away from competition. Moreover, higher dunes may prove to be less frequently inhabited by people, whereas smaller dunes may have camping and other recreation facilities. Previous studies have identified that raptors were heavily present on non-urban beaches compared to a significantly decreased presence on urban beaches (Huijbers et al.
2015). Therefore, higher dunes essentially lead to enhanced breeding success and overall survival.
Other important literature has focused on coastal seabirds as conduits for improved terrestrial ecological productivity. Raptors can transport nutrients to the sand dunes through multiple channels such as their excrement, moulting and their own carrion. This in turn can provide fertilisation for increased vegetation which feeds detritivores and herbivores. Sequentially, this also fuels higher numbers of predators (e.g. lizards, spiders, birds) (S?nchez-Pi?ero & Polis 2000).
In regards to improvements of the study design, better definitions of human inhabited areas (such as access points) are needed, along with longer survey times to adequately identify each variable measured.
Consequently, this study supports the necessity that elevated dune habitat should be heavily protected and are identified as essential nature reserves. There should be restrictions placed on human use of these areas to positively impact the conservation of coastal keystone species such as raptors.