Patricia L. Kennedy

The Effects of Forest Fuel-Reduction Treatments in the United States

The current conditions of many seasonally dry forests in the western and southern United States, especially those that once experienced low- to moderate-intensity fire regimes, leave them uncharacteristically susceptible to high-severity wildfire. Both prescribed fire and its mechanical surrogates are generally successful in meeting short-term fuel-reduction objectives such that treated stands are more resilient to high-intensity wildfire. Most available evidence suggests that these objectives are typically accomplished with few unintended consequences, since most ecosystem components (vegetation, soils, wildlife, bark beetles, carbon sequestration) exhibit very subtle effects or no measurable effects at all. Although mechanical treatments do not serve as complete surrogates for fire, their application can help mitigate costs and liability in some areas. Desired treatment effects on fire hazards are transient, which indicates that after fuel-reduction management starts, managers need to be persistent with repeated treatment, especially in the faster-growing forests in the southern United States.

Managing the whole landscape: historical, hybrid, and novel ecosystems

The reality confronting ecosystem managers today is one of heterogeneous, rapidly transforming landscapes, particularly in the areas more affected by urban and agricultural development. A landscape management framework that incorporates all systems, across the spectrum of degrees of alteration, provides a fuller set of options for how and when to intervene, uses limited resources more effectively, and increases the chances of achieving management goals. That many ecosystems have departed so substantially from their historical trajectory that they defy conventional restoration is not in dispute. Acknowledging novel ecosystems need not constitute a threat to existing policy and management approaches. Rather, the development of an integrated approach to management interventions can provide options that are in tune with the current reality of rapid ecosystem change.

Performance and Accuracy Evaluation of Small Satellite Transmitters

Recent technological advances have resulted in small (30 g) satellite platform transmitter terminals (PTTs) that can be used to track animals with masses as little as 900-1,000 g. While larger PTTs (>80 g) often yield locations accurate to within hundreds of meters, the location accuracy of smaller PTTs has not been tested. We did these tests while using the PTTs to document migration routes and nonbreeding areas of American peregrine falcons (Falco peregrinus anatum). We PTT-tagged 42 female peregrines from 2 breeding areas (upper Yukon River in eastcentral Alaska and Lake Powell on the Colorado Plateau in southern Utah and northern Arizona) late in the breeding seasons of 1993-95. Only 2 of the PTTs failed prematurely (4.7% failure rate). Active PTTs (i.e., PTTs on live birds that eventually stopped transmitting due to battery exhaustion) averaged 280 transmission hours for 1993-94 (n = 3), 380 transmission hours for 1994-95 (n = 7), and 430 transmission hours for 1995-96 (n = 15). Using an estimate of maximum ground speed of peregrines (104 km/ hr) based on empirical observations and aerodynamic calculations, we determined that 4.48% of all locations provided to us by Argos (n = 2.323) were biologically implausible. We also received many poor-quality locations (68% of records were in Argos location classes 0, A. and B) typical of small, relatively underpowered PTTs. To estimate location accuracy of these poor-quality locations, we compared Argos-estimated locations with known locations of 11 rock doves (Columba livia) tagged with PTTs. The location types with the highest precision averaged 4 km from the true location, while the location types with the lowest precision averaged 35 km from the true location. These results indicate the PTT locations were sufficient to document animal movements over broad spatial scales such as identifying migration routes and nonbreeding areas of birds. This technology is more efficient and less biased than the current approaches used to obtain this information (mark-resighting of banded animals or standard radiotelemetry techniques). However, the PTTs currently available are not suitable when position accuracy <35 km is needed.

Meta‐analysis of avian and small‐mammal response to fire severity and fire surrogate treatments in U.S. fire‐prone forests

Management in fire‐prone ecosystems relies widely upon application of prescribed fire and/or fire surrogate (e.g., forest thinning) treatments to maintain biodiversity and ecosystem function. Recently, published literature examining wildlife response to fire and fire management has increased rapidly. However, none of this literature has been synthesized quantitatively, precluding assessment of consistent patterns of wildlife response among treatment types. Using meta‐analysis, we examined the scientific literature on vertebrate demographic responses to burn severity (low/moderate, high), fire surrogates (forest thinning), and fire and fire surrogate combined treatments in the most extensively studied fire‐prone, forested biome (forests of the United States). Effect sizes (magnitude of response) and their 95% confidence limits (response consistency) were estimated for each species‐by‐treatment combination with two or more observations. We found 41 studies of 119 bird and 17 small‐mammal species that examined short‐term responses (≤4 years) to thinning, low/moderate‐ and high‐severity fire, and thinning plus prescribed fire; data on other taxa and at longer time scales were too sparse to permit quantitative assessment. At the stand scale (<50 ha), thinning and low/moderate‐severity fire demonstrated similar response patterns in these forests. Combined thinning plus prescribed fire produced a higher percentage of positive responses. High‐severity fire provoked stronger responses, with a majority of species possessing higher or lower effect sizes relative to fires of lower severity. In the short term and at fine spatial scales, fire surrogate forest‐thinning treatments appear to effectively mimic low/moderate‐severity fire, whereas low/moderate‐severity fire is not a substitute for high‐severity fire. The varied response of taxa to each of the four conditions considered makes it clear that the full range of fire‐based disturbances (or their surrogates) is necessary to maintain a full complement of vertebrate species, including fire‐sensitive taxa. This is especially true for high‐severity fire, where positive responses from many avian taxa suggest that this disturbance (either as wildfire or prescribed fire) should be included in management plans where it is consistent with historic fire regimes and where maintenance of regional vertebrate biodiversity is a goal.

AVIFAUNAL RESPONSES TO FIRE IN SOUTHWESTERN MONTANE FORESTS ALONG A BURN SEVERITY GRADIENT

The effects of burn severity on avian communities are poorly understood, yet this information is crucial to fire management programs. To quantify avian response patterns along a burn severity gradient, we sampled 49 random plots (2001-2002) at the 17351-ha Cerro Grande Fire (2000) in New Mexico, USA. Additionally, pre-fire avian surveys (1986-1988, 1990) created a unique opportunity to quantify avifaunal changes in 13 pre-fire transects (resampled in 2002) and to compare two designs for analyzing the effects of unplanned disturbances: after-only analysis and before-after comparisons. Distance analysis was used to calculate densities. We analyzed after-only densities for 21 species using gradient analysis, which detected a broad range of responses to increasing burn severity: (I) large significant declines, (II) weak, but significant declines, (III) no significant density changes, (IV) peak densities in low- or moderate-severity patches, (V) weak, but significant increases, and (VI) large significant increases. Overall, 71% of the species included in the after-only gradient analysis exhibited either positive or neutral density responses to fire effects across all or portions of the severity gradient (responses III-VI). We used pre/post pairs analysis to quantify density changes for 15 species using before-after comparisons; spatiotemporal variation in densities was large and confounded fire effects for most species. Only four species demonstrated significant effects of burn severity, and their densities were all higher in burned compared to unburned forests. Pre- and post-fire community similarity was high except in high-severity areas. Species richness was similar pre- and post-fire across all burn severities. Thus, ecosystem restoration programs based on the assumption that recent severe fires in Southwestern ponderosa pine forests have overriding negative ecological effects are not supported by our study of post-fire avian communities. This study illustrates the importance of quantifying burn severity and controlling confounding sources of spatiotemporal variation in studies of fire effects. After-only gradient analysis can be an efficient tool for quantifying fire effects. This analysis can also augment historical data sets that have small samples sizes coupled with high non-process variation, which limits the power of before-after comparisons.

Responsiveness of nesting northern goshawks to taped broadcasts of 3 conspecific calls

Because locating nest sites of forest-dwelling raptors is difficult and time-consuming, we determined if broadcasting conspecific vocalizations of northern goshawks (Accipiter gentilis) increased goshawk detectability during the nesting season in northcentral New Mexico (NM) and northcentral Arizona (AZ). We recorded responses of goshawks to an observer who was either broadcasting alarm, wail, or juvenile begging calls, or was not broadcasting at all while walking transects. We sampled 215 transects at 27 goshawk nests during sampling periods associated with courtship, nestling, and fledgling-dependency periods during 1990. Goshawk responses to taped conspecific calls were higher (P = 0.02) than their responses to an observer without a tape

EFFECTS OF SUPPLEMENTAL FOOD ON SIZE AND SURVIVAL OF JUVENILE NORTHERN GOSHAWKS

In 1992 and 1993, 28 Northern Goshawk (Accipiter gentills) broods in north- central New Mexico were used in a supplemental-feeding experiment to determine if there was a causal relationship between food availability and survival of young goshawks. We randomly assigned 28 nests as treatments or controls. Every two days (from hatching (late April) until juvenile dispersal (mid-October)) we visited control nest stands and provided food at treatment nest stands. We measured morphological characteristics and attached tarsal- mounted transmitters with mortality switches to 42 nestling Northern Goshawks when they were 21 days old. In both 1992 and 1993, we relocated birds via telemetry every other day until mid-August. We located birds at least once a week from mid-August until mid-October in 1992, and until late-November 1993. There were no significant differences in nestling size. Treatment birds had a significantly higher survival rate during the nestling period in 1993, but not in 1992. Because most control nestlings died from predation, we attribute higher nestling survival to increased time spent in nest stands by adult females, whose presence probably deterred predators. Received 25 April 1995, accepted 20 August 1995.

DOES HABITAT FRAGMENTATION INFLUENCE NEST PREDATION IN THE SHORTGRASS PRAIRIE

Abstract We examined the effects of habitat fragmentation and vegetation structure of shortgrass prairie and Conservation Reserve Program (CRP) lands on predation rates of artificial and natural nests in northeastern Colorado. The CRP provides federal payments to landowners to take highly erodible cropland out of agricultural production. In our study area, CRP lands have been reseeded primarily with non-native grasses, and this vegetation is taller than native shortgrass prairie. We measured three indices of habitat fragmentation (patch size, degree of matrix fragmentation, and distance from edge), none of which influenced mortality rates of artificial or natural nests. Vegetation structure did influence predation rates of artificial nests; daily mortality decreased significantly with increasing vegetation height. Vegetation structure did not influence predation rates of natural nests. CRP lands and shortgrass sites did not differ with respect to mortality rates of artificial nests. Our study area is only moderately fragmented; 62% of the study area is occupied by native grassland. We conclude that the extent of habitat fragmentation in our study area does not result in increased predation in remaining patches of shortgrass prairie habitat. ¿La Fragmentación de Hábitat Influencia la Depredación de Nidos en Praderas de Pasto Corto? Resumen. Examinamos los efectos de fragmentación de hábitat y estructura de la vegetación sobre la tasa de depredación de nidos artificiales y naturales en praderas de pasto corto y tierras del Programa de Reserva de Conservación (CRP) en el noreste de Colorado. El CRP proporciona pagos federales para que los dueños de las tierras retiren sus cultivos de áreas agrícolas altamente erosionables. En nuestra área de estudio, las tierras de CRP han sido vueltas a sembrar principalmente con céspedes no nativos que son más altos que la vegetación nativa de las praderas de pasto corto. Medimos tres índices de fragmentación de hábitat (tamaño del parche, grado de fragmentación de la matriz, y distancia al borde), ninguno de los cuales influyó sobre la tasa de mortalidad de nidos artificiales o naturales. La estructura de la vegetación influenció la tasa de depredación de nidos artificiales: la mortalidad diaria disminuyó significativamente con incrementos en la altura de la vegetación. La estructura de la vegetación no influenció la tasa de depredación de nidos naturales. Los sitios de CRP y de pastos cortos no difirieron con respecto a la tasa de mortalidad de nidos artificiales. Nuestra área de estudio es sólo moderadamente fragmentada pues el 62% del área es ocupada por prado nativo. Concluimos que el grado de fragmentación de hábitat en nuestra área del estudio no causa aumentos en la depredación en los parches de hábitat remanentes.

Forest structural characteristics of Accipiter nesting habitat : is there an allometric relationship ?

In montane forests of the western United States, a general correlation of Accipiter body size and scaling of the vegetation component of nesting sites and nest trees used by sympatric Accipiter species has been reported. We evaluated this pattern with vegetation data collected at Northern Goshawk (Accipiter gentilis), Coopers Hawk (A. cooperii), and Sharp-shinned Hawk (A. striatus) nest sites in the Jemez Mountains and Pajarito Plateau of north-central New Mexico. We selected habitat variables at the nest tree and nest site scale that would allow us to evaluate the prediction that accipiters use nesting habitat in which their body size is positively correlated with tree size and tree spacing, and inversely correlated with tree density, basal area, and percent canopy closure. At the nest-site level, density of larger diameter trees should be positively correlated with body size, and density of smaller diameter trees should be inversely correlated with body size. Our results suggest that nest tree height and diameter support body size predictions about nesting habitat for accipiter hawks. None of the nest-site parameters measured in this study supported the body size predictions due to a large amount of intra-specific variation. As a result ofthis variation, it was difficult to differentiate between Coopers Hawk and Northern Goshawk nest sites for most site variables. These results suggest there is a correlation between accipiter size and nest tree size, but that a correlation between nest site structural size and accipiter body size may not be a widespread phenomenon for all vegetation variables for all three species. Many commonly measured forest stand structural characteristics such as basal area and total tree densities may not be adequate for predicting suitable accipiter nesting habitat in all areas, particularly in the absence of comparisons with available habitat.

Raptor Electrocution Rates for a Utility in the Intermountain Western United States

Abstract We estimated electrocution rates for raptors and common ravens (Corvus corax) for the Moon Lake Electrical Association in northeastern Utah and northwestern Colorado, USA. From July 2001 to May 2003, we conducted mortality searches at randomly selected distribution line segments and poles within 3 regions, but rate estimates (0.0036–0.0112 deaths/pole/yr) may have been biased by the effects of scavengers and by long sampling intervals (≥3 months), which prevented us from determining the cause of death for most birds because of advanced decay. In 2002–2003, we conducted carcass removal experiments in the Rangely Oil Field (ROF) in northwestern Colorado to estimate scavenging effects, and in 2003–2004, we reduced sampling intervals to 1 month and searched for dead birds at all distribution poles in the ROF. The shorter sampling interval nearly tripled the number of birds suitable for necropsy, but we were still unable to establish cause of death for >40% of our sample. Instead of eliminating the unknowns from rate estimates, we estimated minimum annual electrocution rates using only confirmed electrocutions and maximum annual electrocution rates based on all available mortalities, including mortalities without known causes. Golden eagles (Aquila chrysaetos) accounted for 63% of dead birds found in 2003–2004, but they were removed by scavengers at rates well below hawks and owls (6.8% vs. 55.6%). We compared maximum rates for the ROF in 2003–2004 with the rates estimated from a survey conducted at the same poles in 1999 to assess the effects of retrofitting conducted by Moon Lake from 1999 to 2003. Electrocution rates in 2003–2004 were 47% lower than those in 1999. Raptor densities in the ROF did not change during our study, suggesting the reduction was not the result of changes in raptor populations. However, estimates of raptor densities in 1999 were not available, and we cannot be sure that numbers of birds using the oil field in 1999 were similar to those in 2003–2004. Our research emphasizes the difficulties of estimating electrocution rates precisely but suggests that utilities will have the greatest effect on mortality by monitoring power lines at large scales and focusing subsequent mitigation efforts in areas that pose the greatest risk to the greatest number of birds.