IELTS® Academic Reading Practice 59

The answer is x. Section A describes the fluctuation of the bittern population over time: from being considered extinct in the UK, to recolonization, decline, and finally increasing numbers thanks to conservation efforts. The passage traces the rise and fall and rise again of the population, which matches heading (x) 'fluctuation in bittern population'.

Associated Text:
Bitterns, which are heron-like birds, once prized as a dish for medieval banquets, were considered extinct as a breeding species in the UK by the 1870s. They recolonised the UK in the early 20th century, with a peak of about 80 booming males in the 1950s, but then numbers slid to fewer than 20 in the 1990s. By 1997, the species was facing extinction in the UK again, with there being just 11 males, mainly in Norfolk and Suffolk, with a small outlying population at Leighton Moss, Lancashire. In 2007, the bittern numbers are at a record high.

The answer is v. Section B discusses how researchers developed methods to monitor bittern numbers, focusing on their distinctive 'boom' vocalization during the breeding season. This perfectly matches heading (v) 'Boom vocalizations used to evaluate population'.

Associated Text:
The call, or boom of the male bittern is its most distinctive feature during the breeding season, and we developed a method to count them using the sound patterns unique to each individual one. This not only allows us to be much more certain of the number of booming males in the UK, but also enables us to estimate local survival of males from one year to the next.

The answer is viii. Section C describes how researchers compared different reedbed sites to understand the habitat needs of breeding bitterns and make recommendations for management. This is consistent with heading (viii) 'Identifying the habitat'.

Associated Text:
Our first direct understanding of the habitat needs of breeding bitterns came from comparisons of reedbed sites that had lost their booming birds with those that retained them. This research showed that bitterns had been retained in reedbeds where the natural process of succession, or drying out, had been slowed through management.

The answer is i. Section D details the data collected on the habitat preferences for both male and female bitterns, including nest locations and feeding areas, which clearly aligns with heading (i) 'Collection of data on the habitat'.

Associated Text:
To refine these recommendations and provide fine-scale, quantitative habitat prescriptions on the bitterns preferred feeding habitat, we radio-tracked male bitterns on the RSPB’s Minsmere and Leighton Moss reserves...Over the course of our research, we located 87 bittern nests and found that female bitterns preferred to nest in areas of continuous vegetation, well into the reedbed, but where water was still present during the driest part of the breeding season.

The answer is vii. Section E describes the results after implementing reedbed management techniques, specifically highlighting the technique of 'reedbed lowering' and the subsequent increase in booming bittern numbers. This aligns directly with heading (vii) 'Management technique implemented proved successful'.

Associated Text:
The success of the habitat prescriptions developed from this research has been spectacular. For instance, at Minsmere, booming bittern numbers gradually increased from one to 10 following reedbed lowering, a management technique designed to halt the drying out process.

The answer is iii. Section F focuses on young bitterns, explaining research on chick survival, feeding, and the importance of food (fish) for their survival. This is described in heading (iii) 'A focus on food for young bitterns'.

Associated Text:
The final phase of research involved understanding the diet, survival and dispersal of bittern chicks. To do this we fitted small radio tags to young bittern chicks in the nest, to determine their fate through to fledging and beyond. Many chicks did not survive to fledging and starvation was found to be the most likely reason for their demise.

The answer is iv. Section G covers the development of a network of 19 new sites designed to provide sustainable breeding areas for bitterns beyond their traditional range, aligning with heading (iv) 'Developing new sites to improve successful breeding'.

Associated Text:
A network of 19 sites developed through this partnership project will secure a more sustainable UK bittern population with successful breeding outside of the core area, less vulnerable to chance events and sea level rise.

The answer is vi. Section H provides evidence for a positive trend: increased bittern numbers and extensive reedbed restoration, showing the successful outcome of management efforts, matching heading (vi) 'Positive outcome of bittern population and reedbed area'.

Associated Text:
By 2004, the number of booming male bitterns in the UK had increased to 55, with almost all the increase being on those sites undertaking management based on advice derived from our research...To date nearly 275,000 seedlings have been planted and reed cover is extensive.

The answer is ix. Section I describes the presence of bitterns throughout the winter season and their lingering into the spring, which matches heading (ix) 'Bittern present throughout one season and into the next'.

Associated Text:
Bitterns now regularly winter on the site and there is some indication that they are staying longer into the spring. No breeding has yet occurred, but a booming male was present in the spring of 2004.