The introduction of stubble cultivation rules under nitrates regulations sparked fury among tillage farmers. The practice puts huge pressure on farmers to cultivate within a two-week period of harvest.

The regulations were introduced to establish green cover quickly to take up nutrients and avoid loss to water. However, many farmers already cultivate stubbles, just in a more practical timeframe and in appropriate working conditions.

These regulations require cultivation in extremely dry or wet weather and came into place without due consideration of their impact on biodiversity.

Macra brought the impact of these regulations on endangered bird species to the Department’s attention and the rules were changed from cultivating all cereal stubble to leaving 20-25% of cereal stubble uncultivated, as well as the Department investing into research. The rules remained in place, despite the fact this research was not completed.

However, results from another survey of farmland birds in south Cork are now available. This research is completely separate to the Department of Agriculture’s research.

Farmland birds in decline

Farmland bird numbers are in dramatic decline across Ireland and Europe. The report states that several of these species are highly dependent on seed resources left after harvesting cereal crops, as well as cover crops, and wild bird cover.

The report, entitled ‘An assessment of the winter distribution, abundance and habitat associations of farmland birds on agricultural land in south Cork’, states some of these birds have declined in “abundance”.

Yellowhammer is declining in abundance.

Among these are Yellowhammer, Linnet and Skylark, while noting that more recent changes to regulations under the Nitrates Directive are impacting the area of winter stubbles available.

The project aimed to fill the gap in knowledge on habitats by assessing the diversity, abundance and habitat associations of winter farmland birds on tillage and pasture.

Farms were assessed within a total of 91 areas of 1km2 in south-east Cork. A total of 51 tillage areas were identified, which included winter stubble, cover crops, shallow cultivation and wild bird cover. There were 32 grassland fields used for comparison (see a full list of the farmland birds counted in Table 2).

These areas were visited twice. Once in November to early January and once from mid-January to early March.

Full details are available in the project report, but the birds were surveyed within standard distance bands of 0-25m, 25-100m and over 100m from surveyors. Habitat features were also recorded, like crop type and hedgerow quality. All of the data was downloaded and mapped.

Winter stubble the most important habitat

The results of this survey showed that over-winter stubble (uncultivated stubble) was extremely important for seed-dependent Birds of Conservation, such as the Skylark, Yellowhammer, Linnet, Stock Dove and wintering Snipe (see Figure 1).

The survey showed that the most important field type for winter farmland birds in terms of numbers (48%) and scale was winter stubble.

Winter stubble was the most important field type for Skylark. A percentage of 72% of all records for Skylark in the survey were on over-winter stubble.

The linnet is in decline.

Looking at other species, 56% of Yellowhammers, 39% of Linnet and 41% of Snipe surveyed were found on over-winter stubble.

Wild bird cover was not common in the survey areas, but it was clear that these crops, planted under ACRES, had the highest densities of farmland birds in the survey.

Winter stubble held the highest densities of threatened Birds of Conservation (see Table 1).

“The study strongly indicated that shallow cultivation was significantly poorer for winter farmland birds than winter stubbles,” states the report.

This appears to back up a study in the UK with similar results and it has also been commented on by surveyors carrying out studies on night time use of fields by farmland birds.

The report also stated: “Recent changes to regulations under the Nitrates Directive requiring tillage farmers to shallow cultivate fields within 14 days post-harvest, seriously reduces the extent of winter stubbles which are thought to be critical for the overwinter survival of many farmland birds as they feed on spilt grain and the seeds of arable weeds.”

They added that nothing was known about the possible impacts before the regulations were enforced.

Maintaining winter stubble is the “single most important action”

The report concluded that: “Maintaining or increasing the area of winter stubble, especially unsprayed, is the single most important action to benefit winter farmland birds at scale.

“Retaining stubble as late as possible into the spring before ploughing and sowing a new crop is also important, as late winter (January-March) is an especially hard time impacting the survival of wintering farmland birds, often called the ‘hungry gap’ when seeds left over from the previous crop run out.”

The report also explained that planting crops to feed winter farmland birds under environmental schemes is highly beneficial to these birds, as well as retaining sympathetically managed hedgerow cover for species such as the Yellowhammer.

Dr Allan Mee was the project lead for the winter farmland bird survey.

“The survey results really bring home to us how incredibly valuable a resource winter-stubbles are for farmland birds over the winter,” he said.

“Stubble acts like a large-scale bird table for red-listed and declining bird species such as Skylark and Yellowhammer. The high numbers of Snipe also using winter stubble as well as cover crops was also a real surprise to me.

“Results also clearly show that the loss of winter stubble to shallow cultivation has a seriously negative impact on farmland birds and retention of stubble is of critical importance.”

Allan commented on the interest which the farmers had in bird conservation.

He added: “Retaining winter stubble would be a win-win both for birds and for tillage farmers as it would reduce the time and effort spent having to shallow cultivate land after harvest.”

The project team included: Dr Allan Mee, project co-ordinator, survey reporting; Tom Siekaniec GIS mapping, data collation; Laura Hynes, survey habitat assessment; Laura Kavanagh Data analysis; Paul Moore farm adviser, volunteer surveyor.

The project was funded by the Department of Rural and Community Development, supported by EU Recovery Instrument funding under the rural development programme through the South Cork LAG and SECAD Partnership CLG. The project was also supported by Irish Distillers.