A survey of secondary headteachers and deputes by School Leaders Scotland, in conjunction with TESS, reveals widespread concern about the quality and availability of supply and permanent staff, at both promoted and unpromoted level.
The findings underline the growing crisis around supply cover as the Scottish Negotiating Committee for Teachers continues to wrangle over improved pay for short-term supply teachers.
They also highlight the impact of pension reform, budget cuts and tighter staffing on the recruitment and retention of senior staff.
The survey on staff recruitment was distributed to all 700 SLS members and received 92 responses. That response rate was closer to one in four, said SLS general secretary Ken Cunningham, as the association has members in 380 secondaries and only one member per school was likely to respond.
No respondents find it easy to find supply cover, with 25 per cent finding it "difficult" and 66.3 per cent "very difficult".
Comments attached to the survey reveal the impact of the supply problem, with heads and deputes having to take classes every week.
"There are a number of subject areas where it is impossible to get supply. Since the change to the level of pay for short-term supply the problem has increased significantly," said one respondent.
Another said: "The pay adjustment last session has decimated a previously willing workforce, who feel that they are being taken for granted. It will take years to repair the damage.
"At this stage of implementing Curriculum for Excellence, the lack of supply staff to support developments has been a major hindrance. It has further damaged ethos and staff morale at a crucial moment, making the jobs of senior leaders harder."
Others report that subject-specialist cover is increasingly difficult to find, so teachers are "baby-sitting" classes. Some reveal that certain authorities are continuing to pay the "old" full rate for supply, creating an uneven playing field in the competition for cover staff.
But recruitment problems are not confined to supply: 41 per cent said the quality of applicants for senior posts had worsened in the past four years, while a number of responses complained about appointment processes, with interview leets being drawn up before headteacher references were made available.
"There is too much emphasis on interview performance and an almost disregard of their competency or track record," reported one.
While certain subjects have traditionally been shortage areas, notably home economics and Gaelic, many other posts are now proving difficult to fill, including all the sciences, modern languages, drama, English, technical, business, computing and maths.
The question "Which levels of post does your school have problems recruiting for?" elicited a variety of responses: from temporary posts to unpromoted and supply, all the way up to faculty heads and senior leadership.
"There is also a limited pool of applicants for depute posts that have a strong curriculum background," said one.
Another responded: "We're OK re numbers of applicants. It's the quality that concerns me at times."
Mr Cunningham attributed recruitment difficulties at senior and middle management level to a range of factors - pension changes, job-sizing, workload and accountability responsibilities, changes to child benefit payments and the loss of salary conservation in 2016. He called on education authorities and the government to give senior managers greater moral support in areas such as parental complaints and staff grievance.
Has the quality of applicants for senior posts improved, or otherwise, in the past four years?
- Improved 5.6%
- Stayed the same 37.8%
- Worsened 41.1%
- Don't know 15.6%