A review into the felling of trees beside Britain's railway tracks has been ordered by the Government amid environmental concerns.
Rail minister Jo Johnson told Network Rail to suspend the cutting down of trees during the current bird nesting season except where it was "safety critical".
He warned that "more can be done" to ensure a "gold standard" of vegetation management is applied across the 20,000 miles of tracks managed by Network Rail.
Transport Secretary Chris Grayling told the Press Association: "We want to make doubly sure they're doing it properly. Jo Johnson is looking over their shoulder."
Mr Johnson and Environment Secretary Michael Gove met Network Rail boss Mark Carne on Wednesday to discuss the issue.
An internal Network Rail document shows it is planning to carry out an "enhanced level of clearance" along lines from 2019 to 2024, according to The Guardian.
Mr Johnson said: "How we manage our trees and vegetation - and protect the wildlife that lives in and around them - is an important issue and I understand the concerns of members of the public about how Network Rail does this."
He acknowledged that trees which could be dangerous or cause disruption should be removed, but added: "Cutting back trees can alarm people who enjoy these environments and can especially raise concerns over the effect on birds during nesting season."
Mr Johnson has commissioned a review into vegetation management which will consider whether Network Rail has the ability to carry out work in a way that "minimises harm to wildlife" and whether staff need more training to identify approaches that would be "better than felling".
Tony Whitehead of RSPB in the South West said: "We recognise the need to manage vegetation, especially for urgent safety reasons.
"In fact, selective felling and thinning can provide a habitat mix that is good for wildlife.
"But our call is, please, if it's non-urgent, simply don't do it during the breeding season when birds are nesting."
Network Rail works with the Tree Council and the Woodland Trust in relation to tree felling.
It insisted that the only upcoming alteration to its "policy and standards" was to increase the distance it managed vegetation from five metres to 6.5 metres either side of track with overhead electric wires.
A spokesman said more than 400 trains collided with fallen trees and a further 1,000 incidents were recorded where they caused delays to services, costing the industry over £100 million.
He went on: "We have well thought out standards and policies in place that have been developed over many years with the help of experts that we believe strike the right balance and maintain a safe and biodiverse line side.
"Most of the time when putting those standards and policies into action we get it right, but sometimes we don't."
The spokesman added: "We welcome the review announced by Jo Johnson and the opportunity to further improve."