Infant Survival and Den Site Selection of Female

Raccoons Following Removal and Exclusion From Residences

Anthony DeNicola, Ph.D. from Purdue University, runs White Buffalo a non-profit wildlife research firm. Dr. DeNicola has graciously allowed WDC to reproduce his interim report on a raccoon study being done in Connecticut. All of Dr. DeNicola's copyrights are still in force. If you would like to contact Dr. DeNicola, you can e-mail him at

The issue being studied is what happens to raccoons after they are evicted from residing in a chimney.

This study is being done under the sponsorship of the Connecticut NWCO Association (see their web page ctnwco) and White Buffalo. We hope the study will be completed within the next two years.


Infant Survival and Den Site Selection of Female Raccoons Following Removal and Exclusion From Residences

Annual Report Permit # 9899009

Submitted By White Buffalo Inc.

January 8, 1999


As an obligation of receiving scientific collector's permit #9899009 the following is an interim summary of our field activities and findings. Our primary objective was to determine the fate of captured adult female raccoons and their offspring following their exclusion and subsequent release on site. We have begun assessing the success of reuniting adult females and offspring, infant survival, and selection of alternative nursery sites.



Adult female raccoons were captured using live traps in Hartford County suburban residences (in the towns of Avon, East Hartford, Enfield, Glastonbury, Manchester, Newington, and West Hartford) from 11 April - 26 June 1998. A Nuisance Wildlife Control Operator following requests from homeowners removed each raccoon and their young. All captured raccoons were handled before 1200 h. We anesthetized the adult raccoons according to the proposed protocol and fitted them with radio collars (150-151 MHz range). Adult and infant raccoons were weighed, aged, and examined to determine general condition.

Adult females were placed in a covered cage and allowed to recover from the anesthesia. Infant raccoons were placed in a covered box and left next to the adult female while she recovered. We returned after sunset to release the adult  female and to place the infant raccoons along a travel route near the residence. We followed the protocol developed by the ConnecticutRehabilitators Association for reuniting raccoon family units.

The offspring were checked daily to see if they were retrieved by the adult female. As prescribed in collector's permit, all young not retrieved within 48 hours were assumed abandoned and were euthanized according to AVMA standards. The adult raccoons were radio-tracked for 3 consecutive days following release to determine subsequent nest site selection. We then located den sites for each raccoon every 4-7 days.


Eleven adult female raccoons were captured and handled from 10 April - 26 June 1998. Three of 11 adult female raccoons were captured from 10-14 April and had litters that were 3-4 days old. The litters of the 3 raccoons captured from 26-27 April were 1-3 weeks old. Three raccoons were captured in May with 3-4 week-old offspring. One raccoon removed on 20 June had 7-8 week-old young, and the last raccoon was captured on 26 June with 2-3 week-old young. Estimated dates of parturition were 5 April 5 May, with one late litter born the first week of June.

A total of 35 offspring were handled from the 11 litters (x = 3.2 young per litter). Litter size ranged from 2-4 young. overall an equal number of males (n = 17) and females (n = 18) were produced. The weights of the young ranged from less than 200 g (3-4 days old) to 1.8 kg (7-8 weeks old). The weights of the adult females averaged 5.2 kg, and ranged from. 4.1. - 5.9 kg. All animals were in good condition, with no obvious ectoparasites. All of these data agree with published reports of raccoon weights, ages, and reproductive dates.

    Less than half (n = 4) of the adult females retrieved their young. Of these 4 adult females, 3 retrieved all of the young (all in litter sizes of 3) and the 4th retrieved half of the young (litter size of 4). Of the 11 young retrieved, 7 were female and 4 were male. All young retrieved were either <1 week old (n = 5) or 3-4 weeks old (n = 6). The adult female always required 48 hours to retrieve her offspring. Each adult female usually stayed in a temporary site the first day after release, and then moved to a longer-term den the second day, after retrieving her young.

    We were unable to locate 1 of the radio-collared raccoons. Seven of the remaining 10 raccoons returned to human-built structures (5 in chimneys and 2 Under sheds) within 2 days after removal. The 10 adult females occupied an average of 3.6 sites each during the two months post-capture. The 4 raccoons with young exhibited strong den site fidelity and occupied an average of 1.5 den sites.


Future tasks and recommendations

We believe that the handling protocol may have affected the behavior of the adult female, including retrieval of young. During the second year of the study, with the cooperation of homeowners, we plan to recapture the previously collared raccoons that occupy human-built structures. We will release them and their new litter on site. This will allow us to determine den site selection and retrieval of young with adult females that have not been anesthetized. To compare retrieval rates and den site selection of anesthetized adult female raccoons versus those that are not immobilized we plan to capture and radio-collar 10- more adult female raccoons with young during spring 1999. This also will allow us to attain our proposed sample size of adult females. All raccoons will be tracked using telemetry as described previously.

    In addition to the primary research objectives, adult raccoons will be radio-tracked at night and throughout the year to determine home ranges and measures of habitat use and den site selection. Habitat measurements will be made to determine use versus availability. Finally, relative use of various den types and home range characteristics will be compared across seasons, reproductive status, and habitat availability measurements. Mike O'Donnell, a faculty member from Trinity College's Department of Biology, and 3 senior research students will conduct this research.

White Buffalo 1999

Reprinted with Permission.



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