http://www.ace-eco.org/rss/ The twenty most current aticles published. en Sun, 26 May 2013 03:09:42 EDT http://blogs.law.harvard.edu/tech/rss RA Publishing Systems 2.0.0 managing_editor@ecologyandsociety.org pmorrill@ecologyandsociety.org http://www.ace-eco.org/vol8/iss1/art4/ Silvicultural treatments have been shown to alter the composition of species assemblages in numerous taxa. However, the intensity and persistence of these effects have rarely been documented. We used a before-after, control-impact (BACI) paired design, i.e., five pairs of 25-ha study plots, 1-control and 1-treated plot, to quantify changes in the density of eight forest bird species in response to selection harvesting over six breeding seasons, one year pre- and five years postharvest. Focal species included mature forest associates, i.e., Northern Parula (Setophaga americana) and Black-throated Green Warbler (Setophaga virens), forest generalists, i.e., Yellow-bellied Sapsucker (Sphyrapicus varius) and Swainson’s Thrush (Catharus ustulatus), early-seral specialists, i.e., Mourning Warbler (Geothlypis philadelphia) and Chestnut-sided Warbler (Setophaga pensylvanica), species associated with shrubby forest gaps, i.e., Black-throated Blue Warbler (Setophaga caerulescens), and mid-seral species, i.e., American Redstart (Setophaga ruticilla). As predicted, we found a negative numerical response to the treatment in the Black-throated Green Warbler, no treatment effect in the Yellow-bellied Sapsucker, and a positive treatment effect in early-seral specialists. We only detected a year effect in the Northern Parula and the American Redstart. There was evidence for a positive treatment effect on the Swainson’s Thrush when the regeneration started to reach the pole stage, i.e., fifth year postharvest. These findings suggest that selection harvesting has the potential to maintain diverse avian assemblages while allowing sustainable management of timber supply, but future studies should determine whether mature-forest associates can sustain second- and third-entry selection harvest treatments. Research Paper Fri, 24 May 2013 14:00:48 EDTHache, S., Villard, M., P?try, T. http://www.ace-eco.org/vol8/iss1/art3/ Individual behavior that reduces vulnerability to predation can affect population dynamics of animals. Temperate-nesting Canada Geese (Branta canadensis maxima) have increased steadily throughout the Atlantic flyway and have become a nuisance in some parts of their range. The objective of our study was to describe movements and habitat use during the postbreeding period of Canada Geese recently established in southern Québec. More specifically, we wanted to determine whether geese were using areas where hunting was allowed to assess the potential of harvest to control the number of geese. We tracked a sample of geese fitted with radio or conventional alphanumeric collars throughout the fall in three zones characterized by different habitats and hunting pressure. Before the hunting season, geese left the breeding area where hunting was allowed to reach suburban areas where firearm discharge was prohibited or hunters’ numbers were low. These postbreeding movements occurred when juveniles were approximately three months old. We observed few local movements among zones once migrant geese from northern breeding populations reached the study area. Radio-collared geese used mainly natural habitats (75.4 ± 2.6%), followed by urban (14.4 ± 2.7%), and agricultural habitats (10.3 ± 0.8%). They were located 73.8 ± 6.2% of the time in areas where hunting was prohibited. Geese that attended their juveniles during brood rearing were more prone to use areas where firearm discharge was restricted than geese that had abandoned or lost their brood. This study shows that under the prevailing regulations, the potential of hunting to manage the increasing breeding population of Canada Geese in southern Québec is limited. Research Paper Wed, 24 Apr 2013 13:50:41 EDTBeaumont, M., Rodrigue, J., Giroux, J. http://www.ace-eco.org/vol8/iss1/art2/ We hypothesized that although large populations may appear able to withstand predation and disturbance, added stochasticity in population growth rate (λ) increases the risk of dramatic population declines. Approximately half of the Aleutian Islands' population of Least Auklets (Aethia pusilla) breed at one large colony at Kiska Island in the presence of introduced Norway rats (Rattus norvegicus) whose population erupts periodically. We evaluated two management plans, do nothing or eradicate rats, for this colony, and performed stochastic elasticity analysis to focus future research and management. Our results indicated that Least Auklets breeding at Kiska Island had the lowest absolute value of growth rate and more variable λ's (neither statistically significant) during 2001-2010, when compared with rat-free colonies at Buldir and Kasatochi islands. We found variability in the annual proportional change in population size among islands with Kiska Island having the fastest rate of decline, 78% over 20 years. Under the assumption that the eradication of rats would result in vital rates similar to those observed at rat-free Buldir and Kasatochi islands, we found the projected population decline decreased from 78% to 24% over 20 years. Overall, eradicating rats at Kiska Island is not likely to increase Least Auklet vital rates, but will decrease the amount of variation in λ, resulting in a significantly slower rate of population decline. We recommend the eradication of rats from Kiska Island to decrease the probability of dramatic population declines and ensure the future persistence of this important colony. Research Paper Wed, 24 Apr 2013 09:28:23 EDTMajor, H. L., Bond, A. L., Jones, I. L., Eggleston, C. J. http://www.ace-eco.org/vol8/iss1/art1/ Reproductive success of Common Loons (Gavia immer) is a powerful indicator of aquatic ecosystem health, especially in relation to mercury and acid precipitation. We examined relationships between Common Loon reproductive success and longitude, year, lake area, and pH across southern Canada using data collected from 1992 to 2010 by participants in Bird Studies Canada?s Canadian Lakes Loon Survey. Our goal was to indirectly describe the health of lakes in southern Canada with respect to mercury and acid precipitation. The overall model-predicted number of six-week-old young per pair per year was 0.59 (95% confidence limits: 0.56?0.62). Six-week-old young per pair per year decreased by 0.19 from west-to-east (−127? to −52? longitude), decreased by 0.14 between 1992 and 2010, increased by 0.22 as lake area increased from 10 to 3000 ha, and increased by 0.43 as acidity decreased from pH 5 to 9. The relationships were likely linked to acid- and temperature-mediated exposure to methylmercury and/or acid-induced reductions in forage fish. The temporal decrease was unexpectedly steeper in southwestern than in southeastern Canada. Projections suggested that reproductive success across southern Canada may not drop below the demographic source-sink threshold until ~2016 (range: 2009-2029). Reproductive success on pH 6.0 lakes, however, may have passed below the source-sink threshold as early as ~2001 (1995-2009), whereas reproductive success on pH 8.0 lakes may not pass below the threshold until ~2034 (2019-2062). There were ~0.1 more six-week-old young per pair per year on 2500 ha lakes than on 20 ha lakes. Reproductive success crossed below the source-sink threshold on 20 ha lakes at pH 6.4 (5.8?7.1) and on 2500 ha lakes at pH 5.5 (4.1?6.6). Our results show that citizen science is powerful for monitoring ecosystem health and indirectly support further action to abate emissions of mercury and the harmful components of acid precipitation throughout North America and globally. Research Paper Tue, 26 Mar 2013 11:21:19 EDTTozer, D. C., Falconer, C. Myles, Badzinski, D. S. http://www.ace-eco.org/vol7/iss2/art7/ Editorial Sun, 30 Dec 2012 10:52:58 ESTHobson, K. A., Norris, D., Goldsborough, G., Sealy, S. G. http://www.ace-eco.org/vol7/iss2/art6/ One possible factor that may have contributed to the decline of grassland bird populations is edge avoidance. In the mixed-grass prairie, habitat fragmentation is often caused by juxtaposition of habitats with vegetation that is structurally similar to prairie, making it difficult to understand why birds avoid habitat edges. We hypothesized that display height or resource-use strategy, i.e., the degree to which a species depends on grassland habitat, might explain variation in sensitivity to habitat edges among different species of grassland birds. To test our hypotheses, we used data on the abundance of grassland birds in native mixed-grass prairie fields in southern Alberta, Canada, from 2000 to 2002. Point counts were conducted up to 4.1 km from croplands, 2.2 km from roads, and 1.8 km from wetlands. We used nonlinear regression models to determine the distance at which relative abundance of 12 bird species changed in response to edge, and linear regression to determine if display height or resource-use strategy explained variation in response to different types of edges. Variation in response to edge was not explained by display height or resource-use strategy. However, six species avoided wetland edges, two avoided roads, and four avoided cropland. Two species of conservation concern, Chestnut-collared Longspurs (Calcarius ornatus) and Sprague?s Pipits (Anthus spragueii), declined in abundance by 25% or more within 1.95 km and 0.91 km, respectively, of cropland edges. Because Chestnut-collared Longspurs avoided croplands to at least 1.95 km, it will be important to prevent further fragmentation of mixed-grass prairies by agriculture. Research Paper Tue, 18 Dec 2012 09:02:46 ESTSliwinski, M. S., Koper, N. http://www.ace-eco.org/vol7/iss2/art5/ Expert knowledge-based species-habitat relationships are used extensively to guide conservation planning, particularly when data are scarce. Purported relationships describe the initial state of knowledge, but are rarely tested. We assessed support in the data for suitability rankings of vegetation types based on expert knowledge for three terrestrial avian species in the South Atlantic Coastal Plain of the United States. Experts used published studies, natural history, survey data, and field experience to rank vegetation types as optimal, suitable, and marginal. We used single-season occupancy models, coupled with land cover and Breeding Bird Survey data, to examine the hypothesis that patterns of occupancy conformed to species-habitat suitability rankings purported by experts. Purported habitat suitability was validated for two of three species. As predicted for the Eastern Wood-Pewee (Contopus virens) and Brown-headed Nuthatch (Sitta pusilla), occupancy was strongly influenced by vegetation types classified as ?optimal habitat? by the species suitability rankings for nuthatches and wood-pewees. Contrary to predictions, Red-headed Woodpecker (Melanerpes erythrocephalus) models that included vegetation types as covariates received similar support by the data as models without vegetation types. For all three species, occupancy was also related to sampling latitude. Our results suggest that covariates representing other habitat requirements might be necessary to model occurrence of generalist species like the woodpecker. The modeling approach described herein provides a means to test expert knowledge-based species-habitat relationships, and hence, help guide conservation planning. Research Paper Mon, 03 Dec 2012 10:03:40 ESTIglecia, M. N., Collazo, J. A., McKerrow, A. J. http://www.ace-eco.org/vol7/iss2/art4/ In North America, it is hypothesized that the Golden Eagle?s (Aquila chrysaetos) eastern population declined during the period 1946-1973 because of organochlorine pesticides and other anthropogenic causes of mortality. Since 1970, upward trends for the species have been observed at most eastern hawkwatches. To determine whether such positive trends can be observed on breeding grounds, Golden Eagle counts were performed to monitor nesting territory occupancy between 1994 and 2007 in the Moisie and Sainte-Marguerite River valleys, northeastern Qu?bec. Aerial surveys were conducted during seven of the 14 years. During this period, the number of known nesting territories in the study area increased from 10 to 20, while the number of pairs rose from six to 14. The increase is attributed mostly to investigators? improved experience in finding nests and to their greater familiarity with the study area, and possibly to the growth of the regional population. Occupancy of nesting territories by pairs was very stable over the years. Annual mean % of laying pairs (or laying rate) was 48.0 (SD = 19.9), and productivity (mean number of fledglings per pair) was 0.49 (SD = 0.35). Research Paper Fri, 30 Nov 2012 13:39:07 ESTMorneau, F., Gagnon, B., Poliquin, S., Lamothe, P., D'Astous, N., Tremblay, J. A. http://www.ace-eco.org/vol7/iss2/art3/ Theoretical and empirical studies suggest that well-connected networks of forest habitat facilitate animal movement and contribute to species? persistence and thereby the maintenance of biodiversity. Many structural and functional connectivity metrics have been proposed, e.g., distance to nearest neighboring patch or graph-based measures, but the relative importance of these measures in contrast to nesting habitat at fine spatial scales is not well established. With graph-based measures of connectivity, Euclidean distances between forest patches can be directly related to the preferred gap crossing distances of a bird (functional connectivity). We determined the relative predictive power of nesting habitat, forest cover, and structural or functional connectivity measures in describing the breeding distribution of Hooded Warblers (Setophaga citrina) over two successive breeding seasons in a region highly fragmented by agriculture in southern Ontario. Logistic regression models of nesting occurrence patterns were compared using Akaike?s information criterion and relative effect sizes were compared using odds ratios. Our results provide support for the expectation that nest-site characteristics are indeed related to the breeding distribution of S. citrina. However, models based on nesting habitat alone were 4.7 times less likely than a model including functional connectivity as a predictor for the breeding distribution of S. citrina. Models of nest occurrence in relation to surrounding forest cover had lower model likelihoods than models that included graph-based functional connectivity, but these measures were highly confounded. Graph-based measures of connectivity explained more variation in nest occurrence than structural measures of forest connectivity, in both 2004 and 2005. These results suggest that S. citrina selected nesting areas that were functionally connected at their preferred gap crossing distances, but nesting habitat was a critically important predictor of nest occurrence patterns. Research Paper Thu, 01 Nov 2012 10:40:04 EDTMelles, S., Fortin, M., Badzinski, D., Lindsay, K. http://www.ace-eco.org/vol7/iss2/art2/ Ecological traps are attractive population sinks created when anthropogenic habitat alteration inadvertently creates a mismatch between the attractiveness of a habitat based upon its settlement cues, and its current value for survival or reproduction. Traps represent a new threat to the conservation of native species, yet little attention has been given to developing practical approaches to eliminating them. In the northern Rocky Mountains of Montana, Olive-sided Flycatchers (Contopus cooperi) prefer to settle in patches of selectively harvested forest versus burned forest despite the lower reproductive success and higher nest predation risk associated with the former habitat. I investigated characteristics of preferred perch sites for this species and how these preferences varied between habitats and sexes. I then built on previous research to develop a range of management prescriptions for reducing the attractiveness of selectively harvested forest, thereby disarming the ecological trap. Female flycatchers preferred to forage from shorter perch trees than males, and females’ perches were shorter than other available perch trees. Both sexes preferred standing dead perch trees (snags) and these preferences were most obvious in harvested forest where snags are rarer. Because previous research shows that snag density is linked to habitat preference and spruce/fir trees are preferred nest substrate, my results suggest these two habitat components are focal habitat selection cues. I suggest alternative and complementary strategies for eliminating the ecological trap for Olive-sided Flycatchers including: (1) reduced retention and creation of snags, (2) avoiding selective harvest in spruce, fir, and larch stands, (3) avoiding retention of these tree species, and (4) selecting only even-aged canopy height trees for retention so as to reduce perch availability for female flycatchers. Because these strategies also have potential to negatively impact habitat suitability for other forest species or even create new ecological traps, we urge caution in the application of our management recommendations. Research Paper Thu, 01 Nov 2012 08:47:27 EDTRobertson, B. A. http://www.ace-eco.org/vol7/iss2/art1/ Wilson’s Warbler (Cardellina pusilla; WIWA) has been declining for several decades, possibly because of habitat loss. We compared occupancy of territorial males in two habitat types of Québec’s boreal forest, alder (Alnus spp.) scrubland and recent clear-cuts. Singing males occurred in clusters, their occupancy was similar in both habitats, but increased with the amount of alder or clear-cut within 400 m of point-count stations. A despotic distribution of males between habitats appeared unlikely, because there were no differences in morphology between males captured in clear-cuts vs. alder. Those results contrast with the prevailing view, mostly based on western populations, that WIWA are wetland or riparian specialists, and provide the first evidence for a preference for large tracts of habitat in this species. Clear-cuts in the boreal forest may benefit WIWA by supplying alternative nesting habitat. However, the role of clear-cuts as source or sink habitats needs to be addressed with data on reproduction. Research Paper Tue, 18 Sep 2012 08:14:41 EDTDesrochers, A., Tardif, J., Mazerolle, M. J. http://www.ace-eco.org/vol7/iss1/art7/ Editorial Tue, 26 Jun 2012 12:23:56 EDTNorris, D., Hobson, K. A. http://www.ace-eco.org/vol7/iss1/art6/ Native grasslands have been altered to a greater extent than any other biome in North America. The habitats and resources needed to support breeding performance of grassland birds endemic to prairie ecosystems are currently threatened by land management practices and impending climate change. Climate models for the Great Plains prairie region predict a future of hotter and drier summers with strong multiyear droughts and more frequent and severe precipitation events. We examined how fluctuations in weather conditions in eastern Colorado influenced nest survival of an avian species that has experienced recent population declines, the Mountain Plover (Charadrius montanus). Nest survival averaged 27.2% over a 7-yr period (n = 936 nests) and declined as the breeding season progressed. Nest survival was favored by dry conditions and cooler temperatures. Projected changes in regional precipitation patterns will likely influence nest survival, with positive influences of predicted declines in summer rainfall yet negative effects of more intense rain events. The interplay of climate change and land use practices within prairie ecosystems may result in Mountain Plovers shifting their distribution, changing local abundance, and adjusting fecundity to adapt to their changing environment. Research Paper Tue, 26 Jun 2012 12:01:13 EDTDreitz, V. J., Conrey, R. Yale, Skagen, S. K. http://www.ace-eco.org/vol7/iss1/art5/ Increases in Snow Goose (Chen caerulescens) populations and large-scale habitat changes in North America have contributed to the concentration of migratory waterfowl on fewer wetlands, reducing resource availability, and enhancing risks of disease transmission. Predicting wintering locations of migratory individuals is critical to guide wildlife population management and habitat restoration. We used stable carbon (δ13C), nitrogen (δ15N), and hydrogen (δ2H) isotope ratios in muscle tissue of wintering Snow Geese to discriminate four major wintering areas, the Playa Lake Region, Texas Gulf Coast, Louisiana Gulf Coast, and Arkansas, and infer the wintering locations of individuals collected later during the 2007 and 2008 spring migrations in the Rainwater Basin (RWB) of Nebraska. We predicted the wintering ground derivation of migrating Snow Geese using a likelihood-based approach. Our three-isotope analysis provided an efficient discrimination of the four wintering areas. The assignment model predicted that 53% [95% CI: 37-69] of our sample of Snow Geese from the RWB in 2007 had most likely originated in Louisiana, 38% [23-54] had wintered on Texas Gulf Coast, and 9% [0-20] in Arkansas; the assessment suggested that 89% [73-100] of our 2008 sample had most likely come from Texas Gulf Coast, 9% [0-27] from Louisiana Gulf Coast, and 2% [0-9] from Arkansas. Further segregation of wintering grounds and additional sampling of spring migrating Snow Geese would refine overall assignment and help explain interannual variations in migratory connectivity. The ability to distinguish origins of northbound geese can support the development of spatially-adaptive management strategies for the midcontinent Snow Goose population. Establishing migratory connectivity using isotope assignment techniques can be extended to other waterfowl species to determine critical habitat, evaluate population energy requirements, and inform waterfowl conservation and management strategies. Research Paper Tue, 26 Jun 2012 10:14:45 EDTH?naux, V., Powell, L. A., Vrtiska, M. P., Hobson, K. A. http://www.ace-eco.org/vol7/iss1/art4/ We predicted that bird diversity and abundance of some bird species would be higher in old-growth stands than in mature pine stands because of the greater structural diversity in old growth. We also predicted that patch size of stands should be influential. To test these predictions, we modeled counts of 79 bird species from 52 stands in 5 regions in the province of Ontario, Canada in relation to habitat at the local and landscape extents. Neither total species richness nor abundance differed between stand types. No significant difference was found in bird assemblages between stand types using ordination analysis. However, more Neotropical migrants were found in old-growth stands than in mature stands, while the reverse was true for short-distance migrants. Twenty-five species had higher counts in old-growth stands?three significantly so: Brown Creeper Certhia americana, Northern Parula Setophaga americana, and Scarlet Tanager Piranga olivacea. Supercanopy pine (> 60 cm dbh) was a significant (P < 0.05) positive predictor for Black-throated Green Warbler Setophaga virens, Northern Parula, and total species richness, while medium/large pine (> 40 cm/dbh) was a significant positive predictor for Brown Creeper, Pine Warbler Setophaga pinus, and total species richness. The density of supercanopy and medium/large pine explained a small but significant amount of variation in bird assemblages (1%), after considering age, other tree variables (9%), and landscape metrics. Patch size was significant for Evening Grosbeak Coccothraustes vespertinus and total abundance. According to receiver operating characteristic (ROC) thresholds, Brown Creeper required a minimum of 62 stems/ha of medium/large pine. Pileated Woodpecker Dryocopus pileatus and Black-throated Green Warbler required a minimum of 14 and 23 stems/ha of supercanopy pine, respectively. Blackburnian Warbler Setophaga fusca required a minimum stand age of 66 years. Current targets in shelterwood seed cuts for pine appear to be just within range for Brown Creeper?at least for the first cut, but not for subsequent cuts. We recommend that forest management seek to emulate increased old-growth characteristics in a proportion of managed stands that fall within the range of variation expected under natural variation. Research Paper Tue, 26 Jun 2012 09:45:06 EDTKirk, D. Anthony, Welsh, D. A., Baker, J. A., Thompson, I. D., Csizy, M. http://www.ace-eco.org/vol7/iss1/art3/ Data from the North American Breeding Bird Survey (BBS) suggest that populations of aerial insectivorous birds are declining, particularly in northeastern regions of the continent, and particularly since the mid-1980s. Species that use nest boxes, such as Tree Swallows (Tachycineta bicolor), may provide researchers with large data sets that better reveal finer-scale geographical patterns in population trends. We analyzed trends in occupancy rates for ca. 40,000 Tree Swallow nest-box-years from 16 sites across North America. The earliest site has been studied intensively since 1969 and the latest site since 2004. Nest box occupancy rates declined significantly at five of six (83%) sites east of -78? W longitude, whereas occupancy rates increased significantly at four of ten sites (40%) west of -78? W longitude. Decreasing box occupancy trends from the northeast were broadly consistent with aspects of a previous analysis of BBS data for Tree Swallows, but our finding of instances of increases in other parts of the continent are novel. Several questions remain, particularly with respect to causes of these broad-scale geographic changes in population densities of Tree Swallows. The broad geographic patterns are consistent with a hypothesis of widespread changes in climate on wintering, migratory, or breeding areas that in turn may differentially affect populations of aerial insects, but other explanations are possible. It is also unclear whether these changes in occupancy rates reflect an increase or decrease in overall populations of Tree Swallows. Regardless, important conservation steps will be to unravel causes of changing populations of aerial insectivores in North America. Research Paper Mon, 25 Jun 2012 16:06:43 EDTShutler, D., Hussell, D. J. T., Norris, D. R., Winkler, D. W., Robertson, R. J., Bonier, F., Rendell, W. B., B?lisle, M., Clark, R. G., Dawson, R. D., Wheelwright, N. T., Lombardo, M. P., Thorpe, P. A., Truan, M. A., Walsh, R., Leonard, M. L., Horn, A. G., Vleck, C. M., Vleck, D., Rose, A. P., Whittingham, L. A., Dunn, P. O., Hobson, K. A., Stanback, M. T. http://www.ace-eco.org/vol7/iss1/art2/ Understanding the relative influence of environmental variables, especially climate, in driving variation in species diversity is becoming increasingly important for the conservation of biodiversity. The objective of this study was to determine to what extent climate can explain the structure and diversity of forest bird communities by sampling bird abundance in homogenous mature spruce stands in the boreal forest of the Québec-Labrador peninsula using variance partitioning techniques. We also quantified the relationship among two climatic gradients, summer temperature and precipitation, and bird species richness, migratory strategy, and spring arrival phenology. For the bird community, climate factors appear to be most important in explaining species distribution and abundance because nearly 15% of the variation in the distribution of the 44 breeding birds selected for the analysis can be explained by climate. The vegetation variables we selected were responsible for a much smaller amount of the explained variation (4%). Breeding season temperature seems to be more important than precipitation in driving variation in bird species diversity at the scale of our analysis. Partial correlation analysis indicated that bird species richness distribution was determined by the temperature gradient, because the number of species increased with increasing breeding season temperature. Similar results were observed between breeding season temperature and the number of residents, short-distance and long-distance migrants, and early and late spring migrants. Our results suggest that the northern and southern range boundaries of species are not equally sensitive to the temperature gradient across the region. Research Paper Tue, 19 Jun 2012 14:45:38 EDTDesGranges, J., LeBlanc, M. http://www.ace-eco.org/vol7/iss1/art1/ The effort expended on reproduction may entail future costs, such as reduced survival or fecundity, and these costs can have an important influence on life-history optimization. For birds with precocial offspring, hypothesized costs of reproduction have typically emphasized nutritional and energetic investments in egg formation and incubation. We measured seasonal survival of 3856 radio-marked female Mallards (Anas platyrhynchos) from arrival on the breeding grounds through brood-rearing or cessation of breeding. There was a 2.5-fold direct increase in mortality risk associated with incubating nests in terrestrial habitats, whereas during brood-rearing when breeding females occupy aquatic habitats, mortality risk reached seasonal lows. Mortality risk also varied with calendar date and was highest during periods when large numbers of Mallards were nesting, suggesting that prey-switching behaviors by common predators may exacerbate risks to adults in all breeding stages. Although prior investments in egg laying and incubation affected mortality risk, most relationships were not consistent with the cost of reproduction hypothesis; birds with extensive prior investments in egg production or incubation typically survived better, suggesting that variation in individual quality drove both relationships. We conclude that for breeding female Mallards, the primary cost of reproduction is a fixed cost associated with placing oneself at risk to predators while incubating nests in terrestrial habitats. Research Paper Tue, 01 May 2012 09:50:12 EDTArnold, T. W., Roche, E. A., Devries, J. H., Howerter, D. W. http://www.ace-eco.org/vol6/iss2/art7/ Editorial Fri, 30 Dec 2011 11:27:51 ESTVillard, M., Nudds, T. D. http://www.ace-eco.org/vol6/iss2/art6/ The Marbled Murrelet (Brachyramphus marmoratus) is a threatened alcid that nests almost exclusively in old-growth forests along the Pacific coast of North America. Nesting habitat has significant economic importance. Murrelet nests are extremely difficult and costly to find, which adds uncertainty to management and conservation planning. Models based on air photo interpretation of forest cover maps or assessments by low-level helicopter flights are currently used to rank presumed Marbled Murrelet nesting habitat quality in British Columbia. These rankings are assumed to correlate with nest usage and murrelet breeding productivity. Our goal was to find the models that best predict Marbled Murrelet nesting habitat in the ground-accessible portion of the two regions studied. We generated Resource Selection Functions (RSF) using logistic regression models of ground-based forest stand variables gathered at plots around 64 nests, located using radio-telemetry, versus 82 random habitat plots. The RSF scores are proportional to the probability of nests occurring in a forest patch. The best models differed somewhat between the two regions, but include both ground variables at the patch scale (0.2-2.0 ha), such as platform tree density, height and trunk diameter of canopy trees and canopy complexity, and landscape scale variables such as elevation, aspect, and slope. Collecting ground-based habitat selection data would not be cost-effective for widespread use in forestry management; air photo interpretation and low-level aerial surveys are much more efficient methods for ranking habitat suitability on a landscape scale. This study provides one method for ground-truthing the remote methods, an essential step made possible using the numerical RSF scores generated herein. Research Paper Thu, 01 Dec 2011 07:15:24 ESTSilvergieter, M. P., Lank, D. B.