Ryan Jonnes - Academia.edu (original) (raw)

Papers by Ryan Jonnes

Journal of Field Ornithology, 2020

Forest Science, 2016

The Mexican spotted owl (Strix occidentalis lucida) was listed as a threatened species in 1993, p... more The Mexican spotted owl (Strix occidentalis lucida) was listed as a threatened species in 1993, primarily because of concerns over the loss of late seral forest habitat to timber harvest and wildfire. A recovery plan prepared for this owl subspecies explicitly assumed that nesting (and/or roosting) habitat was a primary factor limiting distribution of Mexican spotted owls and provided four desired conditions for identifying and managing potential owl nesting/roosting habitat in forested habitat. We used data collected at nest sites of Mexican spotted owls in the Sacramento Mountains, New Mexico, to evaluate how well these desired conditions and associated forest structural attributes described nesting habitat in this area. All nest sites included in our analyses successfully fledged young during the study. These nest sites generally featured higher levels of the structural attributes included in the desired conditions (total basal area, density of trees Ͼ46 cm in dbh, percentage of basal area in trees 30-46 cm dbh, and percentage of basal area in trees Ͼ46 cm dbh) than the surrounding stand, yet only 46-87% of sampled nest sites met single desired conditions and only 22% met all four conditions simultaneously. The best generalized linear models using combinations of these four structural attributes plus canopy cover to distinguish between nest sites and random sites within owl home ranges all contained canopy cover and percentage of basal area in trees Ͼ46 cm dbh. Relative importance values were high for both of these attributes (1.000 and 0.983, respectively), and confidence intervals around parameter estimates included zero for all other attributes. The present combination of four desired conditions did not consistently identify nesting habitat in this area, required managing for levels of structural attributes that were greater than levels typically observed at successful owl nest sites, and did not include canopy cover, which was the single best predictor in the Sacramento Mountains. We recommend revising the desired conditions in the Sacramento Mountains to emphasize canopy cover and some attribute measuring the large tree component. We also recommend repeating this assessment in other geographic areas to determine how well the desired conditions for those areas describe nesting habitat for owls.

The Wilson Journal of Ornithology, 2014

Dispersal is a key process influencing population dynamics and gene flow in species. Despite this... more Dispersal is a key process influencing population dynamics and gene flow in species. Despite this, little is known about breeding dispersal in threatened Mexican Spotted Owls (Strix occidentalis lucida), here defined as movement of a non-juvenile owl between territories where it had the opportunity to breed. We observed 28 cases of breeding dispersal during a study of color-banded Mexican Spotted Owls in the Sacramento Mountains, New Mexico, 2003-2011. This represented 4.9% of total opportunities to disperse (n 5 575 observed occasions, range 5 0-9.0% of owls dispersing per yr). Breeding dispersal probability was greater for single owls and paired owls whose mate disappeared or moved than for paired owls whose mate remained in the original territory, greater for subadult than for adult owls, and greater for owls that failed to reproduce the year prior to dispersing than for owls that reproduced successfully. There was some evidence that dispersal probability was greater for female owls and that females dispersed greater distances than males, but dispersal distances generally were small for both sexes of owls (mean distance 5 5.1 and 3.6 km for females and males, respectively). All dispersing owls were paired the first year they were observed in their new territory. Breeding dispersal appeared to occur regularly but at relatively low levels in this population, and dispersal probability appeared to be associated with owl social status, reproductive status, and age prior to dispersal. Because most dispersing owls either were unpaired or lost their mate, and because most failed to reproduce the year prior to dispersal, these owls generally were able to improve their social status and reproductive success by dispersing.

Journal of Raptor Research, 2014

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

The Journal of Wildlife Management, 2013

Information on population dynamics is key to gauging the status of threatened or endangered speci... more Information on population dynamics is key to gauging the status of threatened or endangered species. We monitored demography of a population of threatened Mexican spotted owls (Strix occidentalis lucida) in the Sacramento Mountains, New Mexico from 2003 to 2011. We estimated reproductive output for territorial pairs of owls; used mark-recapture methodology and Pradel's reparameterized Jolly-Seber models to estimate annual apparent survival rates, recapture rates, recruitment rates, and annual rate of population change (l RJS) for 2005-2009; and used estimates of l RJS to assess short-term population viability. Reproductive output was highly variable for 2004-2011, whereas annual apparent survival and recapture rates were less variable among years. Annual rates of population change exceeded 1.0 for both sexes from 2005 to 2009, and empirical observations of numbers of territorial owls supported the model-based trend estimate. Abundance of territorial owls was strongly related to reproduction within the study area, suggesting that population change was driven largely by internal processes. Population viability analyses suggested that population growth was likely to continue in the short term if current conditions persist. The positive growth rates observed in our study populations are encouraging, and may indicate that current recommendations for recovering this owl are succeeding. However, our estimates of l RJS covered a very short time period, given both the potential lifespan of Mexican spotted owls and the extent of temporal variability in weather typical of the southwestern United States. Longer studies of owl demography than we present will be required to understand long-term population trends, and such studies should extend across the range of the subspecies.

The Journal of Wildlife Management, 2013

Understanding the habitat relationships of rare species is critical to conserving populations and... more Understanding the habitat relationships of rare species is critical to conserving populations and habitats of those species. Nesting habitat is suspected to limit distribution of the threatened Mexican spotted owl (Strix occidentalis lucida), and may vary among geographic regions. We studied selection of nesting habitat by Mexican spotted owls within their home ranges in the Sacramento Mountains, New Mexico. We compared characteristics of owl nest trees and nest sites to characteristics of randomly located trees and sites at 2 spatial scales: the general nest vicinity and within activity centers used by spotted owls. Owls nested primarily in mixed-conifer forest (92%), and most nested in cavities in trees or snags (48%), or in dwarf mistletoe (Arceuthobium spp.) witches' brooms (36%). Owl nest trees had greater levels of dwarf mistletoe infection and were larger in diameter than random trees at both of the evaluated spatial scales. Nest trees also were more likely than random trees to be in white fir (Abies concolor) or Douglas-fir (Pseudotsuga menziesii), and in trees or snags with broken tops. Differences between owl nest sites and random sites differed with the scale at which we selected random sites, but at both scales examined, owl nest sites had greater canopy cover and more basal area contributed by large trees and white fir than random sites. In addition, most nest sites occurred in drainage bottoms or on the lower 2 thirds of north-or east-facing slopes. Conservation of owl nesting habitat in this area will require retaining forest patches with high canopy cover and large trees containing cavities or large dwarf mistletoe witches' brooms. Locating forest management treatments on ridgetops or the upper third of slopes and/or on south-or west-facing slopes may reduce impacts to owl nesting habitat while simultaneously targeting the drier forest types most in need of restoration.

Journal of Raptor Research, 2014

A Recovery Plan developed for the threatened Mexican Spotted Owl (Strix occidentalis lucida) reco... more A Recovery Plan developed for the threatened Mexican Spotted Owl (Strix occidentalis lucida) recommended designating Protected Activity Centers (PACs) with a minimum size of 243 ha to conserve core use areas of territorial owls. The plan assumed that areas of this size would protect ''… the nest site, several roost sites, and the most proximal and highly-used foraging areas.'' The PAC concept remains an important component of the recovery strategy nineteen years later, although use of designated PACs by territorial owls has never been evaluated. We assessed use of PACs for nesting and roosting by Mexican Spotted Owls in the Sacramento Mountains, New Mexico, using location data obtained during a study of owl demography from 2004-2011. High proportions of both nest and roost locations were located within the PAC boundary for most, but not all, PACs. Many locations outside of PAC boundaries were adjacent to those boundaries, but some occurred .1 km from PAC boundaries. Proportions of roost locations within the PAC also were high for most, but not all, individual owls of both sexes, and in all years of the study. Proportions of locations within PACs remained relatively high for periods of up to 24 yr following PAC establishment, suggesting that owls continued to use these areas over relatively long periods. A number of vacant PACs were recolonized by owls during the study, and these owls also used PAC areas at high levels in most, but not all, cases. It would be desirable to assess PAC use over longer time periods, in other geographic areas, and to incorporate foraging use in such evaluations. In the meantime, however, our 1 Email address: jganey@fs.fed.us J. Raptor Res. 48(3):210-218

Journal of Field Ornithology, 2020

Forest Science, 2016

The Mexican spotted owl (Strix occidentalis lucida) was listed as a threatened species in 1993, p... more The Mexican spotted owl (Strix occidentalis lucida) was listed as a threatened species in 1993, primarily because of concerns over the loss of late seral forest habitat to timber harvest and wildfire. A recovery plan prepared for this owl subspecies explicitly assumed that nesting (and/or roosting) habitat was a primary factor limiting distribution of Mexican spotted owls and provided four desired conditions for identifying and managing potential owl nesting/roosting habitat in forested habitat. We used data collected at nest sites of Mexican spotted owls in the Sacramento Mountains, New Mexico, to evaluate how well these desired conditions and associated forest structural attributes described nesting habitat in this area. All nest sites included in our analyses successfully fledged young during the study. These nest sites generally featured higher levels of the structural attributes included in the desired conditions (total basal area, density of trees Ͼ46 cm in dbh, percentage of basal area in trees 30-46 cm dbh, and percentage of basal area in trees Ͼ46 cm dbh) than the surrounding stand, yet only 46-87% of sampled nest sites met single desired conditions and only 22% met all four conditions simultaneously. The best generalized linear models using combinations of these four structural attributes plus canopy cover to distinguish between nest sites and random sites within owl home ranges all contained canopy cover and percentage of basal area in trees Ͼ46 cm dbh. Relative importance values were high for both of these attributes (1.000 and 0.983, respectively), and confidence intervals around parameter estimates included zero for all other attributes. The present combination of four desired conditions did not consistently identify nesting habitat in this area, required managing for levels of structural attributes that were greater than levels typically observed at successful owl nest sites, and did not include canopy cover, which was the single best predictor in the Sacramento Mountains. We recommend revising the desired conditions in the Sacramento Mountains to emphasize canopy cover and some attribute measuring the large tree component. We also recommend repeating this assessment in other geographic areas to determine how well the desired conditions for those areas describe nesting habitat for owls.

The Wilson Journal of Ornithology, 2014

Dispersal is a key process influencing population dynamics and gene flow in species. Despite this... more Dispersal is a key process influencing population dynamics and gene flow in species. Despite this, little is known about breeding dispersal in threatened Mexican Spotted Owls (Strix occidentalis lucida), here defined as movement of a non-juvenile owl between territories where it had the opportunity to breed. We observed 28 cases of breeding dispersal during a study of color-banded Mexican Spotted Owls in the Sacramento Mountains, New Mexico, 2003-2011. This represented 4.9% of total opportunities to disperse (n 5 575 observed occasions, range 5 0-9.0% of owls dispersing per yr). Breeding dispersal probability was greater for single owls and paired owls whose mate disappeared or moved than for paired owls whose mate remained in the original territory, greater for subadult than for adult owls, and greater for owls that failed to reproduce the year prior to dispersing than for owls that reproduced successfully. There was some evidence that dispersal probability was greater for female owls and that females dispersed greater distances than males, but dispersal distances generally were small for both sexes of owls (mean distance 5 5.1 and 3.6 km for females and males, respectively). All dispersing owls were paired the first year they were observed in their new territory. Breeding dispersal appeared to occur regularly but at relatively low levels in this population, and dispersal probability appeared to be associated with owl social status, reproductive status, and age prior to dispersal. Because most dispersing owls either were unpaired or lost their mate, and because most failed to reproduce the year prior to dispersal, these owls generally were able to improve their social status and reproductive success by dispersing.

Journal of Raptor Research, 2014

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

The Journal of Wildlife Management, 2013

Information on population dynamics is key to gauging the status of threatened or endangered speci... more Information on population dynamics is key to gauging the status of threatened or endangered species. We monitored demography of a population of threatened Mexican spotted owls (Strix occidentalis lucida) in the Sacramento Mountains, New Mexico from 2003 to 2011. We estimated reproductive output for territorial pairs of owls; used mark-recapture methodology and Pradel's reparameterized Jolly-Seber models to estimate annual apparent survival rates, recapture rates, recruitment rates, and annual rate of population change (l RJS) for 2005-2009; and used estimates of l RJS to assess short-term population viability. Reproductive output was highly variable for 2004-2011, whereas annual apparent survival and recapture rates were less variable among years. Annual rates of population change exceeded 1.0 for both sexes from 2005 to 2009, and empirical observations of numbers of territorial owls supported the model-based trend estimate. Abundance of territorial owls was strongly related to reproduction within the study area, suggesting that population change was driven largely by internal processes. Population viability analyses suggested that population growth was likely to continue in the short term if current conditions persist. The positive growth rates observed in our study populations are encouraging, and may indicate that current recommendations for recovering this owl are succeeding. However, our estimates of l RJS covered a very short time period, given both the potential lifespan of Mexican spotted owls and the extent of temporal variability in weather typical of the southwestern United States. Longer studies of owl demography than we present will be required to understand long-term population trends, and such studies should extend across the range of the subspecies.

The Journal of Wildlife Management, 2013

Understanding the habitat relationships of rare species is critical to conserving populations and... more Understanding the habitat relationships of rare species is critical to conserving populations and habitats of those species. Nesting habitat is suspected to limit distribution of the threatened Mexican spotted owl (Strix occidentalis lucida), and may vary among geographic regions. We studied selection of nesting habitat by Mexican spotted owls within their home ranges in the Sacramento Mountains, New Mexico. We compared characteristics of owl nest trees and nest sites to characteristics of randomly located trees and sites at 2 spatial scales: the general nest vicinity and within activity centers used by spotted owls. Owls nested primarily in mixed-conifer forest (92%), and most nested in cavities in trees or snags (48%), or in dwarf mistletoe (Arceuthobium spp.) witches' brooms (36%). Owl nest trees had greater levels of dwarf mistletoe infection and were larger in diameter than random trees at both of the evaluated spatial scales. Nest trees also were more likely than random trees to be in white fir (Abies concolor) or Douglas-fir (Pseudotsuga menziesii), and in trees or snags with broken tops. Differences between owl nest sites and random sites differed with the scale at which we selected random sites, but at both scales examined, owl nest sites had greater canopy cover and more basal area contributed by large trees and white fir than random sites. In addition, most nest sites occurred in drainage bottoms or on the lower 2 thirds of north-or east-facing slopes. Conservation of owl nesting habitat in this area will require retaining forest patches with high canopy cover and large trees containing cavities or large dwarf mistletoe witches' brooms. Locating forest management treatments on ridgetops or the upper third of slopes and/or on south-or west-facing slopes may reduce impacts to owl nesting habitat while simultaneously targeting the drier forest types most in need of restoration.

Journal of Raptor Research, 2014

A Recovery Plan developed for the threatened Mexican Spotted Owl (Strix occidentalis lucida) reco... more A Recovery Plan developed for the threatened Mexican Spotted Owl (Strix occidentalis lucida) recommended designating Protected Activity Centers (PACs) with a minimum size of 243 ha to conserve core use areas of territorial owls. The plan assumed that areas of this size would protect ''… the nest site, several roost sites, and the most proximal and highly-used foraging areas.'' The PAC concept remains an important component of the recovery strategy nineteen years later, although use of designated PACs by territorial owls has never been evaluated. We assessed use of PACs for nesting and roosting by Mexican Spotted Owls in the Sacramento Mountains, New Mexico, using location data obtained during a study of owl demography from 2004-2011. High proportions of both nest and roost locations were located within the PAC boundary for most, but not all, PACs. Many locations outside of PAC boundaries were adjacent to those boundaries, but some occurred .1 km from PAC boundaries. Proportions of roost locations within the PAC also were high for most, but not all, individual owls of both sexes, and in all years of the study. Proportions of locations within PACs remained relatively high for periods of up to 24 yr following PAC establishment, suggesting that owls continued to use these areas over relatively long periods. A number of vacant PACs were recolonized by owls during the study, and these owls also used PAC areas at high levels in most, but not all, cases. It would be desirable to assess PAC use over longer time periods, in other geographic areas, and to incorporate foraging use in such evaluations. In the meantime, however, our 1 Email address: jganey@fs.fed.us J. Raptor Res. 48(3):210-218