Question..in the time that you have resided (years?) have you noticed declines in any particular species?
Been here about 12 years or so.
Massive decline, to the point of extinction, of Rollers (I would attribute this to factors beyond LT's borders).
Also Steller's Eider as a wintering species, in my first years, flocks of 600-800 birds, as of last couple of years, effectively gone (whether this is actually a decline or simply the birds remaining further north, difficult to say without data from states to the north).
Off the top of my head, can't think of any notable declines in any other species.
On the up, Great White Egret is best example - rare vagrant when I arrived, abundant species now, flocks of 300 on occasion, breeding in several localities. Quite a few species showing slight to moderate rises. Species such as Red-backed Shrike and Wryneck seem in the last one to two years to be rising, very healthy populations of both.
I imagine the E.U. will ultimately screw the population of a few species such as Corncrake and even Montagu's Harrier - currently vast area are semi-abandoned/left fallow, but farmers are now paid by the E.U. to cut grass regardless of whether the grass is wanted/needed. Most farmers cut too early for nesting species, the result predictable. The E.U. should, but does not, link grants to later cutting (a neighbour of mine has asked permission to cut my grass to claim the money - whilst I have given him the go ahead. I stipulate the cutting time). E.U. also funds drainage scheme, so farmers can now have unused dry grass instead of unused wet meadows, the latter umpteen times richer in birds.
But by and large, the country is still incredibly rich (even more so for butterflies, etc) - farming remains low intensity and, given the population is plunging, rural depopulation should ensure it stays this way at least for the near future. Population decline in people due to (a) highest suicide rate in the western world, (b) highest murder rate (drunks killing their drinking buddies in villages), (c) second highest death rate on the roads in Europe, (d) one of the highest per capita levels of emigration (to UK and Ireland, etc).
So back to your original question, have I noticed any declines in particular species - yep, Homo sapiens litanicas (total population in c.1990, 3.7 million, total population today, c.3 million).