Quick Search:

uzh logo
Browse by:

Zurich Open Repository and Archive

Maintenance: Tuesday, 5.7.2016, 07:00-08:00

Maintenance work on ZORA and JDB on Tuesday, 5th July, 07h00-08h00. During this time there will be a brief unavailability for about 1 hour. Please be patient.

Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-35256

Burlet, P; Hegglin, D; Deplazes, P (2010). Efficient age determination: how freezing affects eye lens weight of the small rodent species Arvicola terrestris. European Journal of Wildlife Research, 56(4):685-688.

[img] PDF - Registered users only
View at publisher
Accepted Version


Age determination of animals by measuring the
weight of their eye lenses is a widely used method in
wildlife biology. In general, it is recommended to prepare
lenses immediately after trapping to avoid errors in the age
estimation due to decomposition of lens tissue. However, in
many field studies, large numbers of animals need to be
trapped over long periods of time in huge areas and by
many different field workers. Therefore, the immediate
preparation of eye lenses imposes a considerable logistic
constraint that could be avoided by prior freezing of trapped animals. To assess the impact of freezing, weights of lens of frozen and unfrozen eyes of 114 Arvicola terrestris were compared pair wise. The frozen lenses weighed at average 3.3% (95% CI: 2.4–4.1%) more than the unfrozen ones from the same animals. Freezing time, weight of lenses and mean temperature of the trapping day as an indicator of decomposition speed did not affect the freezing-induced weight increase. Age estimates based on weights of unfrozen lenses varied between 24 and 445 days. Estimates based on frozen lenses were systematically higher.
Applying a constant correction factor of 1.033−1 for the weight of frozen lenses corrects this overestimation of age. We conclude that age determination with frozen lenses of small rodents can yield valid age estimates if a correction factor for freezing is applied. Thus, age determination can be organised much more efficiently in field studies, which is highly advantageous for many ecological, agricultural and epidemiological research projects.


3 citations in Web of Science®
3 citations in Scopus®
Google Scholar™



92 downloads since deposited on 30 Jul 2010
17 downloads since 12 months

Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Institute of Parasitology
04 Faculty of Medicine > Institute of Parasitology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
600 Technology
Uncontrolled Keywords:Short Communication
Date:August 2010
Deposited On:30 Jul 2010 11:19
Last Modified:05 Apr 2016 14:12
Additional Information:The final publication is available at www.springerlink.com
Publisher DOI:10.1007/s10344-010-0390-0

Users (please log in): suggest update or correction for this item

Repository Staff Only: item control page