Electronic books were introduced in 2011 and e-audiobooks the following year.
What started as a small fraction of the service’s lending had grown year by year to about 13% of checkouts last year, a Dunedin City Council spokesman said.
E-audiobooks, or talking books, were the most common form of digital content on offer.
Digital content and licensing restrictions have been the source of some tension in the United States between publishers and libraries, resulting in lawsuits.
Also, rather than sell copies of works, some companies in the US were leasing them to libraries — an approach librarians had labelled "the Netflix model", which they said was more expensive.
Dunedin Public Libraries buys downloadable e-books, e-audiobooks and e-magazines through the digital platform Borrowbox, which negotiates with publishers for rights to make electronic titles available for libraries to lend to borrowers.
A variety of licensing models were used by publishers, the spokesman said.
In most cases, licences allowed library customers to borrow a title a certain number of times, or for a certain time period, after which the licence expired.
These could then be renewed.
Most titles could be used by one person, one at a time, just like a regular library book.
The council spokesman said the approach to lending e-books and other digital content had been in place for some time.
"The range of titles available has increased significantly, which is positive, but we have to balance decisions to purchase and budget limitations, as with all book purchases," he said.
"Some titles remain unavailable for libraries, or prohibitively expensive, so there is room for further improvement in the e-content space."
Dunedin’s service partnered with other libraries to spread costs.
It aimed to provide access to a range of reading and visual material across various formats — including large print, talking books and DVDs — and electronic content was part of the mix.
"These are all important ways of providing for our community, especially for those who do not have access to the internet or digital devices at home," the spokesman said.
"Our staff are also on hand to help members of the public needing assistance, and we can even help with access to low-cost internet modems through the Skinny Jump programme."
