Kapust H.Q.W.,111 Washington Street SE |
McAllister K.R.,10 Maple Park Avenue SE |
Hayes M.P.,00 Capitol Way North
Herpetological Conservation and Biology | Year: 2012
Invasive Reed Canarygrass (Phalaris arundinacea) is widespread in the Pacific Northwest, USA and develops dense, tall stands in shallow wetland habitats. Oregon Spotted Frogs (Rana pretiosa) are a species of conservation concern, and lay eggs in clusters in seasonally flooded margins of emergent wetlands. We hypothesized that reducing Reed Canarygrass might favor Oregon Spotted Frog oviposition in invaded shallows. In a Reed Canarygrass-dominated marsh, we examined probability of oviposition and thermal attributes in 32 pairs of mowed and unmowed plots. Oregon Spotted Frogs laid one cluster of egg masses in each of two mowed plots but no egg masses in unmowed plots, an unlikely result based on a binomial function (P = 0.006). We also recorded three separate Oregon Spotted Frog egg mass clusters outside of study plots, but exclusively in habitat that appeared structurally similar to mowed plots. We conclude that mowing may enhance oviposition habitat for Oregon Spotted Frogs in Reed Canarygrass-dominated wetlands. However, to have confidence in the response given our limited data, this manipulation should be repeated before this management strategy is broadly applied. Future manipulations of this system should consider how such treatments influence other Oregon Spotted Frog life stages and co-occurring species. © 2012. Heather Kapust. All Rights Reserved.
Tidwell K.S.,Portland State University |
Hayes M.P.,00 Capitol Way North
Herpetological Conservation and Biology | Year: 2013
Observations that recently metamorphosed oregon spotted frogs (Rana pretiosa) appear to allow close approach before fleeing led us to contrast their flight initiation distances with those of introduced american Bullfrogs (Lithobates catesbeianus) in order to determine whether this anti-predator variable had the potential to make R. pretiosa vulnerable to predation. using a rangefinder radio-linked to a high-resolution global positioning system unit, we quantified flight initiation distance for recently metamorphosed juveniles of both species using a controlled approach at conboy lake national wildlife refuge, washington state, USA. recently metamorphosed R. pretiosa typically allowed extremely close approach (median flight initiation distance, = 0.07 m, range: 0-6.5 m) with over 30% of frogs approached allowing themselves to be touched prior to fleeing. in contrast, recently metamorphosed L. catesbeianus typically did not allow close approach, always fleeing at distances 3 1.7 m (flight initiation distance, = 6.1 m, range: 1.7-13.9 m). the close approach tactic of R. pretiosa would be consistent with a crypsis-based anti-predator strategy; whereas, L. catesbeianus uses a flight-oriented method of avoiding predation. permitting close approach may place recently metamorphosed R. pretiosa within the typical predatory strike range of L. catesbeianus, which may explain the disappearance of R. pretiosa in areas invaded by L. catesbeianus. Rana pretiosa at conboy lake represents a unique instance of long-term co-occurrence with L. catesbeianus, raising questions about the basis of this co-occurrence.