An official website of the United States government
Abstract Large carnivores were persecuted in Yellowstone National Park, WY, USA, during the late 1800s and early 1900s, leading to extirpation of grey wolves (Canis lupus) and cougars (Puma concolor). Soon thereafter increased herbivory of riparian plant communities by Rocky Mountain Elk (Cervus elaphus) became widespread in the park's northern ungulate winter range or “northern range.” Wolves were reintroduced in 1995–1996, again completing the park's large carnivore guild. In 2004 and 2017, we sampled Geyer willow (Salix geyeriana), a commonly occurring tall willow, along the West and East Forks of Blacktail Deer Creek in the central portion of the northern range. Results indicated high levels of elk herbivory in the 1990s, as in previous decades, not only continued to keep willows short, generally ≤52 cm in height, but also resulted in stream widening and incision, leading to “oversized” channel cross‐sections and a drastically reduced frequency of overbank flows. However, by 2017, willow heights ≥200 cm ( = 310 cm) were prevalent, and canopy cover over the stream, essentially absent in 1995, had increased to 43% and 93% along the West Fork and East Fork, respectively. These recent increases in tall willow heights, greater canopy cover, well‐vegetated streambanks, and the recent development of an inset floodplain all pointed towards a riparian/aquatic ecosystem beginning to recover. Overall, results were consistent with a landscape‐scale trophic cascade, whereby reintroduced wolves, operating in concert with other large carnivores, appear to have sufficiently reduced elk herbivory in riparian areas to initiate the recovery of Blacktail Deer Creek's riparian plant communities and stream channels.
more »
« less
Potential case of pseudo-hermaphroditism in Elk (Cervus canadensis) in Alberta, Canada
Cases of true and pseudo-hermaphroditism, in which animals possess both ovaries and testes or have a single chromosomal and gonadal sex but secondary features of the other sex, have been documented in several cervids, including Odocoileus (deer) and Capreolus (roe deer) species. Another form of intersexuality that has been well documented in Domestic Cattle (Bos taurus) and induced in Red Deer (Cervus elaphus) is freemartinism, where blood is shared between heterosexual twins leading to XX/XY chimeras. We report the first case of pseudo-hermaphroditism in wild Elk (Cervus canadensis), observed in the central east slopes of the Rocky Mountains of Alberta, Canada, from September through December 2019. The Elk had no antlers, exhibited female external genitalia, and displayed male secondary sexual characteristics, including colouring and breeding behaviour. To determine whether this is a case of true hermaphroditism, pseudo-hermaphroditism, or freemartinism would require blood analysis and inspection of internal sex organs by necropsy.
more »
« less
- PAR ID:
- 10322842
- Date Published:
- Journal Name:
- The Canadian Field-Naturalist
- Volume:
- 134
- Issue:
- 3
- ISSN:
- 0008-3550
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Sea urchins are usually gonochoristic, with all of their five gonads either testes or ovaries. Here, we report an unusual case of hermaphroditism in the purple sea urchin, Strongylocentrotus purpuratus. The hermaphrodite is self-fertile, and one of the gonads is an ovotestis; it is largely an ovary with a small segment containing fully mature sperm. Molecular analysis demonstrated that each gonad producedviable gametes, and we identified for the first time a somatic sex-specific marker in this phylum: Doublesex and mab-3 related transcription factor 1 (DMRT1). This finding also enabled us to analyze the somatic tissues of the hermaphrodite, and we found that the oral tissues (including gut) were out of register with the aboral tissues (including tube feet) enabling a genetic lineage analysis. Results from this study support a genetic basis of sex determination in sea urchins, the viability of hermaphroditism, and distinguish gonad determination from somatic tissue organization in the adult.more » « less
-
Abstract Ecosystem structure and processes of coastal temperate rainforests of the Pacific Northwest are thought to be strongly influenced by herbivory primarily of Roosevelt elk (Cervus elaphus roosevelti) and secondarily of Columbian black‐tailed deer (Odocoileus hemionus columbianus). Two large (0.5‐ha) exclosures were built in old‐growth coniferous rainforest communities in Olympic National Park, Washington, during 1979 to study these effects. Cover of shrubs, ferns, herbs, and graminoids and numbers of tree seedlings were described over 36 yr. Results show a sequence following ungulate exclusion of early release of shrubs, ferns, and herbs followed by eventual dominance of shrubs as other vegetation layers become shaded. Short‐term responses of individual species reflected functional traits related to ability to avoid or tolerate herbivory. Over the longer term, effects reflected changing competitive relationships among vegetation layers and other ecosystem dynamics such as the provision of fallen trees in the appropriate decay class to serve as establishment substrate for tree seedlings. In aggregate, vegetation composition shifted after 36 yr from a system dominated by herbaceous cover with a major graminoid component to one dominated by shrubs (5‐ to 6‐fold absolute increase) and ferns (5–7% increase in absolute cover), less absolute herb cover (15–20% loss), and almost no graminoids (<1.5% cover remaining in any plot) after 36 yr. These changes represented a substantial loss in plant community diversity with a loss of 46 of 74 species. Elk abundance outside of the exclosures began to decline in the 1990s leading to parallel changes in plant community trajectories outside of exclosures to those initially seen inside. While this suggests plant community responses inside the exclosures were also driven by elk exclusion, the strength of this response depends on elk abundance.more » « less
-
Anurans can display a host of intriguing sexual syndromes, including hermaphroditism and sex reversal. Using a multifaceted approach for diagnosing and characterising hermaphroditism in the endangered anuran species Rana mucosa, we tracked changes in female reproductive status using hormone monitoring, ultrasound examinations, individual life history, fertilisation records and post-mortem findings. Seven individuals originally sexed as females developed secondary male sexual characteristics, behaviour and hormone profiles and, in some cases, had testicular tissue despite having previously laid eggs. Our results suggest that reproductive technologies can shed light on life history patterns and reproductive anomalies that may affect endangered anuran survival.more » « less
-
Bark beetle outbreaks have impacted millions of acres of conifer forests in Colorado and across western North America, which has altered forest structure and function. These alterations may have significant impacts on the ability of forests to fulfill resource requirements for species that utilize them or modify how they use forests to meet these needs. Ungulates in the southern Rocky Mountains utilize conifer forests to fulfill different aspects of their ecologies. However, there is currently a limited understanding of the unique impacts bark beetle outbreaks have on each species. Using GPS location data for mule deer (Odocoilus hemionus), elk (Cervus canadensis), and bighorn sheep (Ovis canadensis) we created third and fourth order resource selection functions using a use-availability framework. Measures of the beetle kill, along with topographic covariates, were derived from remotely sensed data. Preliminary results suggest that measures of outbreak age, size, severity, and heterogeneity all impact ungulate use of forested areas, however these patterns vary across scale and by species. General trends indicate that older and more severe patches of beetle kill forests with moderate outbreak heterogeneity are selected for by ungulates. Understanding the dynamics of ungulate resource selection under these circumstances is critical to inform both wildlife and forest management strategies, as the impacts of beetle-kill continue to evolve and expand across the west.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.22621/cfn.v134i3.2481
