You need to get in touch with 'Natural England' and report it... and see what they have to say. I'm sure that any destructive work like this would have had to be done by the end of February (possibly by law) and NE should have investigated before the work was carried out..and NE permission would have to be given/granted. Follow it up!
These days Natural England's statutory powers only apply to protected sites (SSSIs, SACs, SPAs) and to species protected under the EU Habitats Directive (Great crested newts, otters, Scottish wild cat, horseshoe bats).
As the site in question isn't any if the above then there is NO legal requirement for NE to have been consulted prior to felling nor any legal requirement for NE's consent.
Felling work can, in principle, be carried out all year round, however under the Wildlife and Countryside Act 1981 (as amended) which covers the protection of wildlife, including birds, their nests and eggs; wild animals, mammals and wild plants.
the law states that it is thus an offence, with certain exceptions, to:
-
'intentionally kill, injure or take any wild bird'
- 'intentionally take, damage or destroy the nest of any wild bird whilst it is in use or being built'
Additional protection is extended to species listed on Schedule 1 of the act, see here:
The RSPB: Wild birds and the law: The Schedules
So felling in March or indeed at any point in the nesting season doesn't constitute an offence - only if one of the conditions above is breached. It's not uncommon for felling on some sites to extend well into the breeding bird season - often this for good reasons such as ground conditions etc, access etc.
The only legal requirement in this case AFAIKS is for a Felling Licence (see previous comment).