Harriers prefer vast open areas where grass is the dominant vegetation. They are a unique and critically endangered ecosystem.
In India large expanses of grasslands as found in Africa are nonexistent and existing patches are under severe pressure from overgrazing, burning and land use change as indicated above. In India, grasslands were never under reckoning for conservation until in recent decades when the charismatic species started to decline. Even then, the grasslands remain categorized as ‘wastelands’ in government records due to the lands being poorly productive for agriculture and forestry they have rarely received any attention or protection (Vanak et al 2013). Wastelands are easy to convert and therefore grasslands turn into farm lands, plantations, industrial conglomerations and urban real estates. In certain cases, grasslands may have also been overprotected and the absence of some forms of tolerable disturbance from human usage and grazing may also lead to their decline (Shahabuddin 2012). Many grasslands are threatened by invasive species such as Prosopis juliflora and decline of quality grassland ecosystem is posing threat to species dependent entirely on such habitats. Some threatened species that are dependent on grasslands and facing severe pressure are the Great Indian Bustard (Ardeotis nigriceps) and Lesser Florican (Sypheotides indicus). Large roosts of harriers recorded from grasslands such as Rollapadu Bustard Sanctuary have also seen a decline in numbers over the last decade.
Harrier and grasslands
India had large tracts of grass and fallow land intermixed with farm lands that supported not only high density of livestock but also harboured some charismatic species of the landscape such as the Wolf, Blackbuck, Great India Bustards, Floricans and many others like the Indian Fox, Coursers, Sandgrouse, Larks, raptors such as Short-eared Owls, Kestrels, Harriers etc.While many of the charismatic species are on decline for various reasons, we know very little about the others.
Harriers require grasslands for roosting and in addition also require grasslands, open scrub and agricultural matrix for foraging. Their population can be linked to the extent and quality of habitat available in the wintering areas.The decline in the European population of some harriers which was suspected to be due to changes in the breeding locations, are now attributed to the changes that may be happening in the wintering habitats (Trierweiler et al 2014).Conversion of the steppe grasslands into farm lands in Europe and northern asia is a major threat for Pallid harriers which is a threatened species. Similarly Montagu Harrier in most parts of Europe remain under constant threat from over-use of pesticides, improved locust control, agricultural intensification and destruction of nests by farm machinery and loss of small mammal and bird prey species (Ferguson-Lees and Christie 2001).
In passage over western asia and other places many migratory birds including harriers are shot while in the wintering grounds, the loss of roosts outside protected areas is a constant threat to harriers. This becomes even more critical when grass quality is poor due to drought and over grazing. In years of good rain also grasslands are transformed to agricultural fields which leaves very little for grassland birds to breed.
Harriers and agriculture have coexisted for centuries, but shifting in agricultural practices is affecting the birds. Harriers feed on locusts/grasshoppers that could be harmful to agriculture. Roger Clarke in a brief survey of harriers in Velavadhar NP estimated harriers to consume in excess of 1.5 million locusts per year in India and also feed on rodents (Clarke 2002). However, use of excessive and potent pesticides may be causing severe damage to the birds. One of the large roosts in South India at Rollapadu around which chemical pesticides are extensively used, no longer seem to support a large population of the birds (Mathew 2007).However, these have to be investigated in detail to understand thelong term impact on Harriers and how their migratory populations are affected.
It well known but less appreciated that grasslands themselves provide key ecosystems services. They prevent soil erosion, store carbon underground and help in water conservation in low rainfall areas apart from the services to local and pastoral communities such as provision of fodder, pastures, materials for roof making, broom making, providing medicinal plants and supporting large herds of sheep and other livestock that are the primary source for the growing meat industry.
In spite of fall in habitat quality, loss of habitat and persecution on passage during migration not everything is lost as far as harriers are considered. In the Netherlands, Montagu Harrier remain under constant threat from over-use of pesticides, improved locust control, agricultural intensification and destruction of nests by farm machinery and loss of small mammal and bird prey species (Ferguson-Lees and Christie 2001).
However, the conservation community there has designed practices that would allow Montagu’s Harrier to breed successfully in such areas before fields are harvested (Koks and Visser 2002). Finding such ways of mutual co-existence is possible, even in India, but requires enhanced cooperation between multiple stakeholders for instance devising ways for protection of harrier roosts in agricultural areas can be one approach of engagement with the farmers.