Pembrokeshire used for farming, compared with 60 per cent for Wales as a whole. Pembrokeshire has a number of seasonal seabird breeding sites, including for razorbill, guillemot, puffin and Manx shearwater, and rare endemic species such as the red-billed chough. Grassholm Island has a large gannet colony. The county's wildlife is diverse, with marine, estuary, ancient woodland, moorland and farmland habitats all within the county. An appeal for otter sightings in 2014 yielded more than 100 responses. Seals, whales, dolphins and porpoises can be seen frequently off the Pembrokeshire coast. Pembrokeshire has numerous prehistoric (such as Pentre Ifan) and historic places,
Pembrokeshire to its proximity to the relatively warm Atlantic Ocean. Inland, average temperatures tend to fall 0.5 °C for each 100 metres increase in height. The air pollution rating of Pembrokeshire is "Good", the lowest rating. The rocks in the county were formed between 600 and 290 million years ago. More recent rock formations were eroded when sea levels rose 80 million years ago, at the end of the Cretaceous Period. Around 60 million years ago, the Pembrokeshire landmass emerged through a combination of uplift and falling sea levels; the youngest rocks, from the Carboniferous Period, contain the Pembrokeshire Coalfield. The