Complex tuition-fee arrangements in different parts of the UK are restricting movement by penning some students in their home countries, analysis suggests.
Final application data for courses with a 15 October deadline show that Northern Irish students are shunning Great Britain, and fewer English students are applying to Scotland.
Across the UK, the number of applicants for courses starting in 2012 at the universities of Oxford and Cambridge, plus medicine, dentistry and veterinary courses elsewhere - which all have an early deadline - fell just 0.8 per cent compared with 2011 figures.
Yet the number of Northern Irish applicants opting for courses in England, Wales or Scotland decreased by 15.2 per cent.
From 2012, Northern Irish students will pay £3,465 per year if they study in their own region, but up to £9,000 for courses in the rest of the UK.
Meanwhile, the number of Scottish applicants - who will pay nothing to study in Scotland but up to £9,000 everywhere else - applying to courses with a 15 October deadline in England fell 13.7 per cent.
A spokeswoman for Universities Scotland said that using figures for 15 October programmes was "far more reliable" than using data for all 2012 courses as, for other programmes, students have until 15 January to apply.
She said that "to a certain extent the cross-border exchange (between England and Scotland) does seem to be slowing" and predicted that the 13.7 per cent drop will be greater still by January, since "if you're dead set on Oxford and Cambridge you're set on Oxford and Cambridge, regardless of fees".
English applicants, who will have to pay up to £9,000 wherever they study in the UK, have continued to turn their backs on Scottish universities. The number of English applicants to Scotland has dropped 7.6 per cent, following a 14.9 per cent drop in early-deadline applications the previous year.
Four-year courses mean that gaining a degree north of the border will, on average, be more expensive for English students, partly due to additional living costs.
The number of English students applying to Welsh universities for courses with a 15 October deadline also declined 7.4 per cent, despite universities in Wales charging just £400 more on average than English institutions.
A spokesman for Higher Education Wales said that while "nobody is being complacent", the changes were "relatively modest on courses that are massively oversubscribed".
In 2009-10, Welsh universities relied on English students for more than 40 per cent of their undergraduate intake.
In a separate development, Queen's University Belfast has set fees for rest-of-UK students at £9,000 a year, with a £2,500 annual bursary for those who achieve AAB at A level. It follows the University of Ulster's decision to set fees of between £6,000 and £8,000 for rest-of-UK students.