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Home Range and Habitat Use of Santa Rosa Island Foxes (Urocyon littoralis santarosae)Drake, Elizabeth Marie 01 March 2013 (has links)
Island foxes (Urocyon littoralis) are currently listed as federally endangered on four of the six Channel Islands to which they are endemic. The Santa Rosa Island (SRI) population declined by 99% during the 1990’s due to non-native golden eagle (Aguila chrysaetos) predation and is currently the lowest fox population (~280) and density (0.86 foxes/km2) of any of the Channel Islands. The goals of this study were to assess new miniaturized GPS technology and to quantify home range and habitat use of the SRI population. This is only the second use of Global Positioning System (GPS) collars on Channel Island foxes and provides essential baseline data for the recovering population. These results can be used to guide management decisions and future habitat restoration efforts after the recent removal of non-native ungulates.
In fall 2009, 14 GPS collars were deployed on male foxes on the east side of SRI. Nine collars and three remote download datasets were recovered in 2010. The collars’ battery life was 40% lower than expected at an average (±SE) of 16.5 ± 1.7 weeks but had high performance in precision and fix rate. Collars yielded an average of 347 ± 33 locations with a fix rate of 82.3% ± 2.1% and 88% of locations categorized as high precision.
From these data, 95% minimum convex polygon (MCP) home ranges and 95% kernel density isopleth (KDI) home ranges were created. The average 95% MCP home range size was 3.39 ± 0.59km2 and the area of overlap with adjacent home ranges had a median of 5.3%. The average 95% KDI home range size was 3.82 ± 0.68km2 with a median overlap of 6.0%. These home range sizes are almost triple the size reported in other island fox studies, likely due to the low fox densities in the recovering SRI population.
Habitat analysis was performed using KDI home ranges and a Euclidian distance analysis (EDA) method to assess habitat selection within the study area, the home range and the core area. Results showed selection for lupine within the study area, which no previous studies have documented. There was no significant habitat selection within the home ranges or core areas. Foxes selected for valley bottom topography and for bare and grassland habitat at night. One shortcoming of EDA is that its reliance on random points for determining second order selection can lead to unused areas being identified as selected habitat. The lack of significant selection within home ranges and core areas may be attributed to small sample sizes, use of male foxes only and the timing of the study in relation to fox reproductive biology.
I recommend further investigation in the use of lupine habitat and associated resources through prey inventory studies to further assess these findings. When densities reach historic levels of 4 foxes/km2, follow up studies should be conducted to reassess home range size, overlap and habitat use to determine if home range sizes have decreased and overlap has increased. Future studies should incorporate spring and summer seasons and females to determine if foxes select a particular habitat within the core area during denning and pupping periods.
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Measuring Social Compatibility in Channel Island Foxes: How Does Intra-pair Aggression Affect Breeding Success?Calkins, Elizabeth S 01 January 2009 (has links) (PDF)
These chapters were written as three separate papers for publication. After the island fox (Urocyon littoralis) underwent a period of severe population decline, the National Park Service began a captive breeding program to increase their numbers. Here, I identify the factors influencing the breeding success of pairs in captivity to formulate strategies that could increase productivity. I compiled a database of variables including litter size, reproductive success, distance to nearest occupied pen, subspecies, exposure, female age, male age, age difference, female and male origin (wild vs. captive born), years paired, previous reproductive success by the pair, previous reproductive success by the female, mate aggression related injuries reported, and previous involvement in an aggressive pair. I performed linear multiple regression to identify factors related to litter size, and logistic regression to predict the probability of reproductive success. A larger interpen distance, higher male age, less exposure, and a smaller intra-pair age difference positively affected litter size. The probabilities of reproductive success increased with interpen distance, lower female age, fewer years paired, and less exposure. Comparatively, pairs with wild born females (vs. captive born females), previously successful pairs (vs. previously unsuccessful and new pairs), and pairs with a previously unsuccessful female (vs. untried and previously successful females) were most likely to be successful. These results suggest that the ideal situation and pairing would be to pair young wild-caught females with older males in sheltered pens that are as far from other pens as possible, while maintaining successful pairs and repairing unsuccessful pairs.
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Effective Environmental Management of the National Park Service: A Case Study of Channel Islands National ParkOlmsted, Daniel T. 01 January 2010 (has links)
The topic of protected area management serves as the focal point of my thesis. The fundamental question I seek to answer is; what constitutes effective environmental management and how is it exemplified in the National Park Service (NPS)? How exactly does the NPS continually earn the trust and confidence of the American people when so many other government agencies are viewed in a negative light? How does the Channel Islands National Park, in particular, shape the economic and political framework in which it operates to achieve its goals? How does this agency effectively manage such a complex ecosystem spanning across five unique islands and the surrounding waters? More specifically, I examine how the NPS designs and implements strategies to simultaneously monitor a variety of endemic species, some of which are on the endangered species list, into feasible tasks and fundable projects. A wealth of information exists providing salient recommendations for improving endangered species recovery efforts, but this paper provides a detailed comparison of two contemporary recovery programs dealing with independent declines of the same species: the island fox. Finally, there is an overlapping mix of jurisdiction responsible for protecting the Channel Islands and I will also be examining the collaborative processes that take place among the multiple stakeholders such as the U.S. Navy, Catalina Island Conservancy, and The Nature Conservancy. The primary purpose of this thesis is to assess the relationships the NPS develops with other agencies in order to fulfill its mission within the context of the Channel Islands.
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