Habitat use and activity patterns of northern porcupine (Erethizon dorsatum) in northwestern Chihuahua, Mexico.
The North American porcupine is a little known species in Mexico, it has been reported in a few locations north of the country and is considered an endangered species.
The design of the collar turned very suitable for this species, webbing sling adapted very well to the porcupine’s body which is full of spines
The project is under the direction of Gerardo Ceballos Ph. D., Rurik List Ph.D., biologists Jesus Pacheco and Eduardo Ponce from Wildlife Ecology Conservation Laboratory, Institute of Ecology UNAM, and Gerardo Suzan Ph. D., from Faculty of Veterinary Sciences, UNAM and it is funded by T & E Inc, JM Kaplan and IDEAWILD.
The North American porcupine is a little known species in Mexico. Although it is a species with a wide distribution in the United States and Canada, Mexico has been reported in a few locations north of the country and is considered an endangered species (SEMARNAT, 2002). The only breeding population registered in the country is located northwest of Chihuahua. During the last decades both livestock and agriculture have been the dominant activities in the region, which has caused serious problems of habitat fragmentation for many species. The purpose of the study is to generate information on the ecology of the porcupine, such as use and habitat selection, activity patterns and assess whether or not populations of this species have been affected by habitat fragmentation.
Although porcupines are considered generalist herbivores, they may show preferences for certain tree species either as their main food source or as a place of rest. Six individuals have been fitted with a radio transmitter (TXE-311CB, TELENAX), in order to identify the sites used by porcupines as resting, reproduction, protection and / or feeding. They have been followed for up to one year with a three-element Yagi antenna.
The average weight and length of adults was 7.1 kg and 69 cm, of the offspring was 2 kg and 48 cm. Porcupines were found in riparian vegetation, oak forest, rocky slopes and mainly arid scrub mesquite. During sampling, preferences for the type of vegetation changed, in the winter, when the females are pregnant and there is less availability of food, their home range was lower than in summer and not far away from the burrows . During spring born calves stayed very close to the mother during the following months. Porcupines were mainly active at night, but sometimes as a result of weather conditions such as rain or snow they were active during the morning.
Trees and shrubs usage
During the day porcupines were found either resting on the branch of a tree or at the base of a bush. The species used were trees like sycamore (Platanus wrightii), ash (Fraxinus velutina), Chinese (Celtis reticulata), poplar (Populus angustifolia), oak (Quercus emory and Quercus spp.), Walnut (Juglans major) and shrubs such as mesquite (Prosopis glandulosa), juniper (Juniperus depeana and J. spp.), manzanita (Artoctaphylos spp.) and cholla (Opuntia imbricata). The Sycamores are important because they provide burrows and protection, mesquites are also important because these bushes provide food and effective protection against predators, especially when the young is very small.
Tracking porcupines with a three element Yagi TELENAX antenna.
The northern porcupine can be found resting in the shade of a tree or at the base of a bush. They have primarily nocturnal habits.
The collar Model TXE-311CB from Telenax was designed with two sling straps allowing the collar to adapt to the individual spines.
During May-June 2007 were placed six collars that worked well emitting very good signal for 14 months. After this period they occasionally emit a different sound, which were like 5 beeps per second, and sometimes emitted a very low signal. One of the collars apparently stopped working at 12 months and we could not recover it (Note from Telenax: This model has an expected life between 9.6 and 14 months depending on activity of the animal because more activity drains more power from the activity-inactivity-mortality sensor) . In 2008 we replaced two collars. Antennas and receivers have worked very well, have very practical functions that facilitate the work to follow up.
The signal was very good, as the terrain where porcupines move is mostly a plateau. The reception distance also depends on the position of the porcupine, when he was at ground level the range was about 2 km (1.25 miles), when they are in the mountains the reception was very low because the animals shelter in rocky canyons. Overall we had no trouble locating individuals, except for the times when the animals were in an underground burrow.
I am satisfied with the equipment that we acquired as it allowed me to meet the objectives of the project by knowing more movements of this species which is threatened by habitat loss and fragmentation, and evaluating the likely causes that limit its distribution. The design of the collar turned very suitable for this species, webbing sling adapted very well to the body which is full of porcupine spines. The weight of 33 grams was excellent for the 7.3 kg average adult’s weight. And the weight of the receiver and antenna at around 1.5 kg were good for us to work with.
It was a good experience to work in the field for almost two years with the equipment. Groups of researchers, writers, photographers and cowboys have participated as volunteers in tracking and catching porcupines, with whom we promote the values and respect for nature. We were surprised by storms, high winds, rattlesnakes, peccaries, bobcats. The ranch owners are very interested in learning more about the life of porcupines and other flora and fauna.
By tracking we discovered the months in which the offspring is born, how they move in the first months of life, the places where they have their burrows and their use of habitats in different seasons of the year.
The study has determined the movements of six animals and their relation to habitat fragmentation that exists in that region (Photo Veronica Solis)
Management of porcupine. Once tranquilized, each individual is weighed, measured and sex determined before putting on a radio.
Preparing for releasing.
Article submitted by Biologist Eduardo Ponce from the National University of Mexico (UNAM)
Telenax wishes to thank Eduardo Ponce, Gerardo Ceballos, Rurik List and the UNAM for sharing this article.