Lakeshore Habitats Research Articles

Species Composition, Relative Abundance and Habitat Association of Avifauna in Zegie Peninsula Forest Patches and Associated Wetlands, Bahir Dar, Ethiopia

The study about species composition, relative abundance and habitat association of avian fauna in Zegie Peninsula forest patches and associated wetlands was carried out from August 2018 to March 2019, covering both the wet and dry seasons. Forest, shrub, lakeshore and wetland were habitats. Data were collected using point count and line transect methods, for 24 days. A total of 96 species of birds were identified. Out of the total, 40 species were observed during the wet season; 13 during dry and 43 species in both seasons. There was statistically significance variation of species distribution among habitats (χ2=11.89, df=3, p=0.008). During the wet season, the highest species diversity was recorded in the wetland habitat (H’=3.3) followed by forest habitat (H’= 2.9). During the dry season, avian diversity was highest in lakeshore (H’=2.58) followed by wetland (H’=2.51). Highest evenness was observed in the shrub land (E=0.87) and (E=0.84) during the wet and dry seasons, respectively .During the wet season, the highest species similarity was recorded between wetland and lakeshore habitat (SI=0.39) and during the dry season the highest species similarity was recorded between forest and shrub habitats (SI= 0.6). 64(66.66%) of the avian species were uncommon. Currently, however, the species diversity in the area decreases. This might be due to various anthropogenic activities such as deforestation of trees for timber and cutting tree for fire wood. Therefore, awareness creation should be given to the local community to reduce habitat destruction. Keywords/Phrases: Bird diversity, relative abundance, wetlands, Zegie Peninsula, DOI: 10.7176/JBAH/12-11-01 Publication date: June 30 th 2022

Development of a shore typology of Lake Constance (Germany) using spatial analyses

Population growth and tourism exert tremendous pressures on the lakeshore habitats of Lake Constance. However, great efforts have been put into shore restoration measures over the last few decades to generate a more natural state. These activities, and the importance of the littoral zone as a UNESCO world cultural heritage, increase the need for comprehensive shore typology data to provide a decision base for littoral zone management. Our approach comprises the delineation and classification of different regions of the littoral zone based on morphological features as a first step towards a comprehensive shore typology. We applied a combination of spatial and statistical analyses to classify the Lake Constance shore, based on width and slopes at different depths. We classified ten different hydro-morphological shore types, each representing homogenous areas in the littoral zone separated into sublittoral zones and potential flood areas. Validation of the typology revealed that the shorelines with steep inclinations or embankments were the shore types most likely to erode. Our findings show that the typology based on morphological features can be a useful predictor and method to link the structures and processes that interact in the shore area with the shore morphology.

Species Composition, Relative Abundance, and Habitat Association of Avifauna in Zegie Peninsula Forest Patches and Associated Wetlands, Bahir Dar, Ethiopia

Introduction. Ethiopia is one of the most avifauna rich countries in Africa. Avifaunal surveys are required to inform conservation decisions and enhance land management for biodiversity. Avifaunal surveys from Ethiopia are lacking. This study examines species composition, relative abundance, and habitat association of avian fauna in Zegie Peninsula forest patches and associated wetlands from surveys carried out from August 2018 to March 2019, covering both the wet and dry seasons. Data Collection. Forest, shrub, lakeshore, and wetland habitats were identified as ecologically relevant habitats in the study area for data collection. Data were collected using point count and line transect methods, for 24 days in total for both seasons in the morning and afternoon. Results. A total of 96 species of birds were identified during the whole study period. Out of the total, 40 species were observed during the wet season, 13 during dry and 43 species in both seasons. There was significant variation of species distribution among habitats. During the wet season, the highest species diversity was recorded in the wetland habitat followed by forest habitat. During the dry season, avian diversity was the highest in the lakeshore followed by wetlands. The highest evenness was observed in the shrubland during both the wet and dry seasons. During the wet season, the highest species similarity was recorded between wetland and lakeshore habitats, and during the dry season, the highest species similarity was recorded between forest and shrub habitats. Based on encounter rate data, 64 (66.66%) of the avian species were uncommon. Conclusions. Compared to previous studies conducted in the study area, species diversity was lower. This might be due to various anthropogenic activities such as deforestation of trees for timber and cutting trees for firewood. Therefore, awareness creation should be given to the local community to reduce habitat destruction due to various human-induced factors.

Distinct microhabitats affect the relative balance of ecological processes shaping the spatial distribution of bacterial communities in lakeshore habitats

Abstract The lakeshore habitat, which is an interface zone between lake and land, harbours various organic particles providing nutrient‐rich microhabitats for bacterial colonisation. Revealing the mechanisms maintaining the bacterial diversity generated on these particles is vital for understanding the biogeochemical processes within lakeshore habitats. To date, however, the bacterial communities within lakeshore habitats have been rarely explored, and knowledge of the ecological processes associated with their spatial distribution is limited. Here, we employed amplicon‐based high throughput sequencing technology to investigate the composition, co‐occurrence patterns, spatial distribution, and assembly processes of free‐living and particle‐attached bacterial communities (FLBC vs. PABC) across 29 lakeshore zones within freshwater lakes from two typical regions: Middle–Lower Yangtze River Plain and Yunnan–Kweichow Plateau. We found significant community dissimilarity between both bacterial lifestyles and regions. PABC exhibited higher community dissimilarity between the plain and plateau regions than FLBC did. Furthermore, eight operational taxonomic units were detected as a core bacterial community within the lakeshore habitats across the plain and plateau regions. Network analysis revealed that bacterial taxa preferring a particle‐attached lifestyle exhibited more co‐occurrence associations for both intra‐ and inter‐community than the free‐living lifestyle. Both FLBC and PABC showed significant distance–decay relationships in these two regions. Dispersal limitation was the most important process associated with patterns in the spatial distribution of FLBC and PABC, whereas the relative importance of variable and homogeneous selection differed between the assembly of FLBC and PABC because of differences in their microhabitats. Our results highlight that dispersal limitation may be strongly associated with the spatial distribution of lakeshore bacterial communities at a regional scale. However, lifestyle differences influence the relative balance between the processes of dispersal, selection, and biotic interaction that influence these bacterial communities. This study reveals potential interactions between bacterial taxa with different lifestyles as well as indicating which ecological processes may lie behind the spatial distribution of bacterial communities in lakeshore habitats. Knowledge of potential assembly mechanisms of bacterial communities within different microhabitats help us understand how bacterial communities in different microhabitats are generated and their different roles in biogeochemical processes in lakeshore habitats.

Reproductive success and health of breeding Bank Swallows (Riparia riparia) in aggregate (sand and gravel) pit and natural lakeshore habitats

Abstract Bank Swallows (Riparia riparia) are designated as Threatened in Canada, in part due to loss of natural breeding habitat along lakeshores and rivers. Excavation in sand and gravel pits (aka aggregate pits) has increased availability of potential nesting habitat away from lakes and rivers, and these substitute habitats may be important to stabilize the decline experienced by some Bank Swallow populations. Over 2 yr, we collected data on Bank Swallow reproductive success from 2 natural lakeshore habitat sites along bluffs of the north shore of Lake Ontario and 7 aggregate pits in southern Ontario, within 100 km of the lakeshore. Nests at the lakeshore habitat were initiated earlier than in aggregate pits, 8 days earlier in 2014 and 13 days earlier in 2015. Neither clutch size nor number of nestlings were different between the 2 habitat types. There were differences in the number of fledglings produced between the habitat types, with Bank Swallows nesting in aggregate pits raising more fledglings per successful nest. However, birds nesting in aggregate pits also had significantly more nests that raised no fledglings, even though eggs in those nests hatched. Breeding adults from aggregate pits were initially heavier than those from the lakeshore habitat, but their mass decreased significantly over the nesting season. Fledgling masses were not significantly different between habitat types. Parasite loads on fledgling Bank Swallows from aggregate pits were significantly lower than on fledglings from the lakeshore. These indicators suggest that aggregate pits can provide at least equivalent habitat for Bank Swallows to that provided by natural lakeshore habitat, making them potentially key for the recovery of this species in Ontario.

Contrasting patterns of macroinvertebrates inshore vs. offshore in a plateau eutrophic lake: Implications for lake management

Worldwide there has been deterioration of lakeshore habitat and increasing eutrophication. These stresses have impacted littoral macroinvertebrate communities. However, bioassessment and rehabilitation have been largely carried out offshore, and the inshore macroinvertebrates have received less attention especially in shallow plateau lakes. In this study, we compared inshore and offshore macroinvertebrate communities in a shallow plateau lake, Lake Dianchi, China. The environmental parameters determining the distribution of macroinvertebrates were analyzed with partial redundancy analysis. Our results showed that macroinvertebrate communities differed significantly between inshore and offshore. Taxonomic richness was much higher inshore than offshore, due to higher habitat heterogeneity. By contrast, both density and biomass inshore were significantly lower than those of offshore. Generally, vegetation and substrate type were the key environmental parameters shaping macroinvertebrate communities. Eutrophication exerted great effect on offshore communities, while its impacts on inshore communities varied spatially. Shoreline degradation and seasonal eutrophication effects resulted in the limited density and biomass of inshore communities. Our results emphasized the significance of inshore habitats for macroinvertebrates in Lake Dianchi, and provided important implications for bioassessment and ecological rehabilitation in shallow lakes.

Effects of Scale and Gender on Winter Habitat Selection by American Mink

Mammalian carnivores have adapted to successfully occupy a wide range of environments spanning tropical to polar ecosystems. Some species, however, have evolved in ways that constrain their ability to thrive in extreme environmental conditions. For example many members of the Family Mustelidae are vulnerable to extreme temperatures resulting from their tubular body shape. The American mink (Neovison vison) likely faces these temperature constraints, being a smaller-bodied mustelid that ranges over a large portion of North America. Mink are largely understudied in its native range with knowledge being particularly sparse with respect to winter ecology. During 2011–2012 we conducted winter telemetry on seven adult mink and used resource selection function models to assess habitat selection patterns while considering spatial extent and gender. We found that at a larger extent, the animals' use of habitat was strongly linked to riparian features, whereas this effect was less noticeable at a finer scale. The larger males selected more lakeshore habitat, whereas the smaller females generally were near smaller streams with both selecting for beaver modified habitat. While we recognize the limited sample size in our study, we speculate that this spatial separation could be linked to higher energetic costs for females to forage aquatically in winter because of their smaller body size. This may make females more sensitive to competition from other forest carnivores (e.g. American marten) as well as impacts from resource development activities.

Restoring hardwood trees to lake riparian areas using three planting treatments

AbstractLake riparian areas provide wildlife habitat for a wide variety of species. Residential development throughout such lakeshore areas of the United States has increased exponentially in recent decades. Awareness of the vulnerability and importance of lakeshore ecosystems has increased concurrently. Lakeshore habitat restoration projects have been implemented to mitigate some of the negative impacts of human shoreline development, and containerized (CT) trees are frequently one of the highest costs associated with such restoration projects. As an alternative, we tested the effectiveness of using dormant bare‐root (BR) trees in restoration projects along two lakeshores in northern Wisconsin, U.S.A. In addition, we experimented using BR stock that was incorporated into gravel medium at a local nursery and planted later in the summer months. We monitored growth and survival of four native tree species in these three planting treatments over a 3–4‐year period. CT red maple (Acer rubra), paper birch (Betula paperifera), and northern red oak (Quercus rubra) increased in size significantly faster than BR and/or gravel culture (GC) counterparts, whereas CT showy mountain ash (Sorbus decora) growth rates were similar to those of BR and GC stock. Mortality was generally low, but for those species/planting treatments with higher mortality (paper birch and red oak), CT trees were more likely to survive than BR or GC trees. Our results show that the success of deciduous BR and/or GC tree stock relative to CT trees is species dependent, and for some species, CT trees' higher growth rates and survivorship could offset their higher costs.

Conifer restoration on lakeshores using 3 planting techniques

Interest in lakeshore habitat restoration has increased concomitant with growing awareness of the importance of these areas for maintaining water quality and for providing terrestrial and aquatic wildlife habitat. Lakeshore restoration efforts are often limited by the high cost of suitable plant material. We compare the effectiveness of containerized and more cost-effective bareroot and innovative gravel-culture planting techniques for 5 conifer species: balsam fir ( Abies balsamea (L.) Mill. [Pinaceae]), white spruce ( Picea glauca (Moench) Voss [Pinaceae]), red pine ( Pinus resinosa Aiton [Pinaceae]), eastern white pine ( Pinus strobus L. [Pinaceae]), and northern white cedar ( Thuja occidentalis L. [Cupressaceae]). Plantings were monitored for 4 growing seasons (year of planting and 3 subsequent). Annual growth rates for 4 of the 5 species did not differ significantly among planting techniques. The exception was containerized balsam fir, which experienced a greater height growth rate than did bareroot and gravel-culture stock. Survival of gravel-culture stock was greater than that of bareroot stock and similar to that of containerized stock for all of the conifers examined, except for red pine. Red pine gravel-culture stock had the lowest survival of any species or treatment (29%), suggesting that this technique is poorly suited for this species. We conclude that the time frame for bareroot native conifer planting may be extended for most of the species examined through the midsummer months by growing bareroot stock in irrigated gravel medium until lifting and planting. For some species, however, neither bareroot planting technique is likely to equal or exceed the growth and survival of containerized stock in lakeshore restoration. Haskell DE, Bales AL, Webster CR, Flaspohler DJ, Meyer MW. 2017. Conifer restoration on lakeshores using 3 planting techniques. Native Plants Journal 18(3):235–244.

Pleistocene footprints show intensive use of lake margin habitats by Homo erectus groups

Reconstructing hominin paleoecology is critical for understanding our ancestors’ diets, social organizations and interactions with other animals. Most paleoecological models lack fine-scale resolution due to fossil hominin scarcity and the time-averaged accumulation of faunal assemblages. Here we present data from 481 fossil tracks from northwestern Kenya, including 97 hominin footprints attributed to Homo erectus. These tracks are found in multiple sedimentary layers spanning approximately 20 thousand years. Taphonomic experiments show that each of these trackways represents minutes to no more than a few days in the lives of the individuals moving across these paleolandscapes. The geology and associated vertebrate fauna place these tracks in a deltaic setting, near a lakeshore bordered by open grasslands. Hominin footprints are disproportionately abundant in this lake margin environment, relative to hominin skeletal fossil frequency in the same deposits. Accounting for preservation bias, this abundance of hominin footprints indicates repeated use of lakeshore habitats by Homo erectus. Clusters of very large prints moving in the same direction further suggest these hominins traversed this lakeshore in multi-male groups. Such reliance on near water environments, and possibly aquatic-linked foods, may have influenced hominin foraging behavior and migratory routes across and out of Africa.

Impact of changing flood regime on a lakeshore plant community: Long-term observations and individual-based simulation

Disturbance events shape plant communities depending on the disturbance regime as well as on the properties of the species constituting the community. We studied a lakeshore community at Lake Constance, a pre-alpine lake in Central Europe, where disturbance by flooding has a strong impact as the water level is almost not regulated by man. The lakeshore habitats are shaped by annual summer flooding during the vegetation period of plants, with seasonal course and magnitude of water-level fluctuations varying considerably between years. By a combination of field work and modelling we examined (1) whether flooding tolerance and interactions between individuals can explain zonation and species coexistence at lakeshore, (2) how strongly invasive species are affecting habitat specific species, and (3) whether changing flooding regimes due to potential climate changes will affect species composition.The study was based on a long-term monitoring record (23 years; 1988–2005) of presence/absence of six species along two transects in a species-poor community at Lake Constance and on detailed records of annual flooding. We succeeded in parameterizing a spatially explicit individual-based life-cycle model of community dynamics on a pattern-oriented basis. This gave results on species demography, dispersal, and interactions. The parameterized model could be verified along additional data recorded in 2011.The results of model parameterization showed that the habitat specialists (characteristic species for the studied lakeshore community) will be able to coexist with stable zonation over the coming decades, mainly due to a contrast between flood tolerance and strength of competitive interactions forming a variant of the competition–colonization trade-off model of coexistence. As a consequence, long-term shortening of the average flooding period, as predicted for the future, should negatively affect flood-tolerant but weakly competing habitat specialists. Here, an avoiding strategy, a shift of flood-tolerant plant species to lower parts of the lakeshore beyond transect boundary and hence beyond present model range, is to be expected.The modelling results revealed that two native but invasive species will have an increasing impact on the community, and they are predicted to endanger habitat specialists on a long run. This was verified already by the re-examination in 2011. Following the parameter values, invasive species threatening the lakeshore community are both flood-tolerant and competitive. Their expected importance for the fate of the community even exceeds that of possible changes in flood duration.The study demonstrates that an individual-based model can be developed on the basis of nonstationary, temporally and spatially changing local abundance data. Such a model goes beyond conventional matrix modelling by the inclusion of nonlinear features as a consequence of individual interactions, and such features turn out to be decisive factor for dealing with species coexistence and displacement in a plant community.

Estimating the risks of multiple, covarying stressors in the National Lakes Assessment

AbstractThe National Lakes Assessment (NLA) used relative and attributable risks to measure the apparent nationwide effects of excess N, reduced lakeshore habitat, and other stressors on planktonic assemblages in lakes. The risk measures, borrowed from human health research, use nontechnical language to compare the apparent effects of disparate lake stressors, thereby helping the public and policymakers identify stressors of greatest national concern. However, the investigators for the NLA and similar prior surveys of streams did not adjust their risk estimates of each stressor for possible confounding by other covarying stressors. As a result, the NLA point estimates overstate the risks of individual stressors and, thus, are unreliable for assessing their importance relative to that of closely related stressors. I used NLA data from 966 lakes to illustrate existing statistical methods of risk adjustment. Point estimates of adjusted relative risk for 7 stressor variables were 15 to 64% lower than unadjust...

Developmental plasticity of immune defence in two life-history ecotypes of the garter snake, Thamnophis elegans - a common-environment experiment

1. Ecoimmunological theory predicts a link between life-history and immune-defence strategies such that fast-living organisms should rely more on constitutive innate defences compared to slow-living organisms. An untested assumption of this hypothesis is that the variation in immune defence associated with variation in life history has a genetic basis. 2. Replicate populations of two life-history ecotypes of the garter snake Thamnophis elegans provide an ideal system in which to test this assumption. Free-ranging snakes of the fast-living ecotype, which reside in lakeshore habitats, show higher levels of three measures of constitutive innate immunity than those of the slow-living ecotype, which inhabit meadows around the lake. Although this pattern is consistent with the ecoimmunological pace-of-life hypothesis, environmental differences between the lakeshore and meadow habitats could also explain the observed differences in immune defence. 3. We performed a common-environment experiment to distinguish between these alternatives. Snakes born and raised in common-environment conditions reflected the immune phenotype of their native habitats when sampled at 4 months of age (i.e. fast-living lakeshore snakes showed higher levels of natural antibodies, complement activity and bactericidal competence than slow-living meadow snakes), but no longer showed differences when 19 months old. 4. This suggests that the differences in innate immunity observed between the two ecotypes have an important - and likely age-specific - environmental influence, with these immune components showing developmental plasticity. A genetic effect in early life may also be present, but further research is needed to confirm this possibility and therefore provide a more definitive test of the ecoimmunological pace-of-life hypothesis in this system.

Stopover Habitat Along the Shoreline of Northern Lake Huron, Michigan: Emergent Aquatic Insects as a Food Resource for Spring Migrating Landbirds

AbstractRecent work in Michigan's eastern Upper Peninsula suggests that terrestrial areas bordering northern Lake Huron provide important stopover habitat for spring migrating landbirds, principally because of the presence of emergent aquatic midges (Diptera: Chironomidae). Migrants were concentrated in lakeshore habitats abundant with midges during spring migration. American Redstarts (Setophaga ruticilla) and Black-throated Green Warblers (Dendroica virens) foraged and used habitat differently, depending on their distance from the lakeshore. Here, we describe results of an integrative study in which we sampled resources, quantified American Redstart foraging behavior, and estimated mass change in American Redstarts and five other common migrant landbird species to evaluate the importance of adult midges as an early season resource for spring migrants. Resource sampling and American Redstart foraging behavior suggested that more food was available in shoreline habitats than inland during spring migration. Furthermore, migrants gained mass in shoreline habitat during stopover, which supports the argument that nearshore areas provide important stopover habitat for spring migrants. Finally, resource sampling, mass change estimates, and American Redstart foraging behavior suggested that midges and spiders (Araneae: Arachnidae) provided an important early season resource for migrating landbirds. Evidence suggests that midges were responsible for elevated spider abundance at the shoreline and that birds foraged on both midges and spiders. Midges appear to play an important role in providing high-quality stopover habitat for landbirds migrating through Michigan's eastern Upper Peninsula.Hábitat de las Paradas Migratorias a lo Largo de la Costa Norte del Lago Huron, Michigan: Insectos Acuáticos Emergentes como Recurso Alimenticio para las Aves Terrestres Migratorias Durante la Primavera

STOPOVER HABITAT ALONG THE SHORELINE OF NORTHERN LAKE HURON, MICHIGAN: EMERGENT AQUATIC INSECTS AS A FOOD RESOURCE FOR SPRING MIGRATING LANDBIRDS

Abstract Recent work in Michigan's eastern Upper Peninsula suggests that terrestrial areas bordering northern Lake Huron provide important stopover habitat for spring migrating landbirds, principally because of the presence of emergent aquatic midges (Diptera: Chironomidae). Migrants were concentrated in lakeshore habitats abundant with midges during spring migration. American Redstarts (Setophaga ruticilla) and Black-throated Green Warblers (Dendroica virens) foraged and used habitat differently, depending on their distance from the lakeshore. Here, we describe results of an integrative study in which we sampled resources, quantified American Redstart foraging behavior, and estimated mass change in American Redstarts and five other common migrant landbird species to evaluate the importance of adult midges as an early season resource for spring migrants. Resource sampling and American Redstart foraging behavior suggested that more food was available in shoreline habitats than inland during spring migratio...

Germination characteristics of lakeshore plants under an artificially stabilized water regime

To examine the possibility of the failure of lakeshore plants to germinate under an anthropogenically controlled water regime, we investigated physiological germination responses to temperature and inundation among 25 lakeshore plant species from Lake Kasumigaura, Japan. The requirement of low temperature for dormancy breakage, which is common in spring-germinators, was seen in 14 species. Eight species showed sensitivity to temperature fluctuation, which is thought to be relevant to bare ground detection for germination. Seed germination of most species was significantly reduced under inundation. Seedling emergencies under outdoor conditions in which the wet and inundated conditions of the natural lakeshore habitat were simulated showed that the timing of all species was concentrated in spring. A significant reduction of emergence in the inundated condition was observed in 19 species. Therefore, most of the lakeshore plant species are adapted to germinate in spring on exposed bare ground during low-water periods. The recent imposition of water level control with a winter-spring elevation possibly prevents regeneration of most common lakeshore plants through the loss of seasonal safe sites for germination.

European lake shores in danger — concepts for a sustainable development

In Europe, when small (> 0.01 km 2) lakes are considered, approximately 500,000 natural lakes occur. This considerable number points to the fact that lakeshore habitats and ecosystems are of significant importance to the total biodiversity of European landscapes, not only because of their expanse, but also because they are ecotones between land and water, which attract many kinds of wildlife, economical, cultural and recreational uses and human settlement. These very considerable stretches of shore are not currently registered, mapped or evaluated anywhere. Apart from providing habitat, the littoral biocoenosis performs a string of additional functions in the ecosystem, of which several are also of great importance to people, such as self purification, buffer zone, erosion protection and recreation scenery. In particular, the recreational function provides a main economic base for many lake areas and even whole countries in Europe. However, human interests have resulted in lake shore deterioration, such that many European lakes are now bare natural shores or retain only relics of them. Apart from the loss of the ecological functions, this also leads to a substantial loss of economic benefits. This precipitates the need for a responsible management, which can be done only on the base of a sound assessment method and a continuous monitoring of the status of lake shore areas. On a European scale, the European Water Framework Directive (WFD, 2000/60/EC) and the Habitat Directive (92/43/EEC) provide the frame for the assessment and monitoring of the status of littoral habitats of lakes. The WFD focuses on entire surface water bodies, including their associated wetlands under influence of their natural water-level fluctuations. However, the provided set of quality elements has to be adapted for an approach specific to lake shores. Apart from quality elements indicating the natural spatial pre-requisites, biocoenotic diversity and integrity, and ecosystem function and dynamics, also quality elements representing the human pressure of land use and the social and economic value of the lake shore zone should be included in an integrated lakeshore assessment and monitoring concept. However, the application of such an integrated quality assessment scheme requires an integrated administrative counterpart, just as the WFD requires for water management aspects on a catchment scale. Only by overcoming the splitting of competence among a variety of authorities and planning corporations can an integrated approach to sustainable shore development be translated into action.

Influence of lakeshore development on breeding bird communities in a mixed northern forest

We report findings of a 2-year study (1996–1997) surveying breeding birds in lacustrine habitats of northern Wisconsin, USA. This area has seen marked increases in lakeshore housing development in recent years, and other studies indicate significant lakeshore habitat alteration. We paired developed and undeveloped lakes of similar physical characteristics and performed point-counts around the perimeter of each to assess bird community structure. Our results showed no significant differences between developed and undeveloped lakes in bird abundance, richness or species diversity. However, several species and some resource-guilds were commonly associated with one lake-type or the other. We found a significantly higher diversity of diet guilds on developed lakes. Significant declines in the prevalence of insectivorous and ground-nesting birds were documented on developed lakes, contrasting with increased prevalence of seed-eating birds and deciduous-tree nesting birds. Levels of development on lakeshores in northern Wisconsin appear to affect the composition of avian communities, which is of concern for the health of these forested lacustrine habitats. We outline several factors associated with development which may be linked to these observed bird community changes and suggest measures landowners might take to minimize impact on native breeding bird communities.

Experimental evidence for the adaptive evolution of growth rate in the garter snake Thamnophis elegans.

The western terrestrial garter snake (Thamnophis elegans) varies significantly in individual growth rates and life-history traits (maturation, reproduction, and survival) among adjacent populations in nature. This study focuses on assessing the genetic and environmental components of the substantial among-population variation in growth rates. Litters of neonates from nine populations inhabiting either mountain meadow or lakeshore habitat were reared for one year in a common-garden experiment with two temperature treatments. Diet, frequency of feeding, light exposure, and daytime temperatures were identical for all individuals. The two different nighttime temperatures (20 degrees C and 25 degrees C) were chosen to mirror field differences in nighttime thermoregulatory constraints for mountain-meadow and lakeshore snakes, respectively. Temperature and source habitat interacted to affect first-year growth rate. Neonates from meadow dams grew fastest in the cooler treatment, whereas those from lakeshore dams grew fastest in the warmer treatment. The observation that naive neonates, which were gestated and raised under identical conditions, grew fastest in environments characteristic of their natal population is evidence both that there are genetic differences among populations for growth and that these differences reflect adaptation to local habitats at a very small geographic scale. In addition, significant directional selection for large birthweight was measured for neonates from all populations. These results are considered in the context of population colonization history, migration and selection, and competing models for growth rate variation.

Seed dormancy/germination traits of seven Persicaria species and their implication in soil seed‐bank strategy

In order to predict species‐specific potential to form persistent soil seed‐banks and to characterize the dynamics of their seed‐banks, the seed dormancy/germination traits of seven Persicaria (Polygonum s.lat.) species sharing lakeshore habitats in central Japan were examined. Strict light requirements for seed germination were not observed in any of the species examined. Although all species required moist chilling (0–6 weeks) to break seed dormancy and were sensitive to temperature fluctuation, the degree of both responses varied between species. Seed germination of Persicaria hydropiper (L.) Spach, Persicaria lapathifolia (L.) S.F. Gray, and Persicaria longiseta (De Bruyn) Kitag. was more accelerated by temperature fluctuation and required shorter chilling periods compared with Persicaria japonica (Meisn.) H. Gross, Persicaria maackiana (Regel) Nakai, Persicaria thunbergii (Sieb. et Zucc.) H. Gross, and Persicaria sieboldi (Maisn.) Onki. Secondary dormancy was induced in all species at higher temperatures (24 and 30°C). A persistent seed‐bank strategy suggested by the dormancy/germination traits of the studied species was also demonstrated by seedling emergence from surface soils collected from the natural habitat immediately before seed dispersal, as well as by viable seed persistence for 13 months in the field in a seed burial experiment. In the natural habitat, the species with longer chilling requirements occurred in various microhabitats, including the interior of moist tall grasslands, whereas the species having higher sensitivity to temperature fluctuation were most frequently found in sparsely vegetated microhabitats.