The savannah sparrow territorial system: can habitat features be related to breeding success?

1984 ◽  
Vol 62 (9) ◽  
pp. 1819-1828 ◽  
Author(s):  
Jean Bédard ◽  
Gisèle LaPointe
Keyword(s):  
Breeding Success ◽  
Plant Cover ◽  
Territory Size ◽  
Breeding Performance ◽  
Mating Status ◽  
Passerculus Sandwichensis ◽  
Habitat Features ◽  
Savannah Sparrow ◽  
Territory Holder ◽  
Selection Of

We studied the biology of the savannah sparrow (Passerculus sandwichensis) in a tidal marsh – abandoned fields ecotone at Isle Verte, Québec, from 1976 to 1981 in an attempt to relate habitat features of the territories (size, vegetation structure and height, food abundance, and an index of foraging opportunities) with breeding success (success in attracting a mate and in fledging at least one young). The height of plant cover did not influence the selection of nesting areas by females. The index of foraging opportunities was highly variable and could not be related to the age of the territory holder (yearling or older), his mating status (breeder or bachelor), or to his breeding success (success in fledging at least one young). Territory size was not consistently influenced by these factors. We propose several reasons for the lack of relation between breeding performance and those features of habitat quality that we studied.

scholarly journals Effects of Plant Cover Improvements for Nesting Ducks on Grassland Songbirds

2003 ◽  
Vol 117 (2) ◽  
pp. 167
Author(s):  
Stéphane Lapointe ◽  
Luc Bélanger ◽  
Jean-François Giroux ◽  
Bernard Filion
Keyword(s):  
Plant Cover ◽  
Abundant Species ◽  
Major Effect ◽  
Passerculus Sandwichensis ◽  
Dolichonyx Oryzivorus ◽  
Forage Plants ◽  
Grazing System ◽  
Savannah Sparrow ◽  
Grassland Songbirds ◽  
St Lawrence River

Several islands located along the St. Lawrence River in southern Quebec have been used as natural pastureland by cattle for decades. Recently, a rest-rotation grazing system and dense nesting cover were established on four islands near Varennes to improve duck nesting conditions. The effects of these two plant cover improvements on the abundance of grassland songbirds were assessed through four treatments: (1) idle fields with no vegetation improvement but exclusion of cattle (IDLE), (2) improved pastures with seeding of forage plants for cattle (IMPP), (3) dense seeded nesting cover fields improved for ducks and where cattle were excluded (DNC), and (4) natural or unimproved pastures grazed by cattle after the duck nesting season (UIPP). The overall abundance of birds was similar among treatments before cover improvements as well as two years after. The abundance of Bobolinks (Dolichonyx oryzivorus) was significantly greater in DNC and UIPP two years after treatments while Red-winged Blackbirds (Agelaius phoeniceus) were more abundant in DNC and IDLE. Plant cover improvements had little impact on Savannah Sparrow (Passerculus sandwichensis) abundance. Furthermore, few annual or treatment-related changes were observed for less abundant species. On the short-term, duck nesting cover improvements in natural pastures did not have any major effect on grassland songbirds on Varennes islands.

Song characters as reliable indicators of male reproductive quality in the Savannah Sparrow (Passerculus sandwichensis)

2020 ◽  
Vol 98 (1) ◽  
pp. 32-38
Author(s):  
Ha-Cheol Sung ◽  
Paul Handford
Keyword(s):  
Sexual Selection ◽  
Reproductive Performance ◽  
Territory Size ◽  
Male Mating ◽  
Combined Effects ◽  
Male Quality ◽  
Passerculus Sandwichensis ◽  
Song Variation ◽  
Savannah Sparrow ◽  
Savannah Sparrows

Bird song may provide female birds with signals of male quality. To investigate this potential for sexual selection via female choice, we assessed the relationships between male song variation and male mating and reproductive success of the Savannah Sparrow (Passerculus sandwichensis (J.F. Gmelin, 1789)) over 3 years (2001–2003) in a population of Savannah Sparrows near London, Ontario, Canada. We measured song rate, as well as temporal and frequency attributes of song structure, as possible predictors of male quality, and then related these measures to attributes of male reproductive performance (mating and breeding success and territory size of males). We found significant correlations between male reproductive performance and several song features, such that the combined effects of two trill sections could potentially play an important role: males possessing such songs arrived and paired earlier and had higher fledging success. The results suggested that the trill segments of the song may signal important aspects of male quality. Possible reasons for significant roles of such songs in open-habitat birds are discussed.

Territoriality and habitat selection of female snowy owls (Nyctea scandiaca) in winter

1982 ◽  
Vol 60 (10) ◽  
pp. 2344-2350 ◽  
Author(s):  
Peter C. Boxall ◽  
M. Ross Lein
Keyword(s):  
Habitat Selection ◽  
Prey Availability ◽  
Constant Level ◽  
Territory Size ◽  
Small Areas ◽  
Edge Habitat ◽  
Adult Females ◽  
Resource Poor ◽  
Territory Holder ◽  
Selection Of

Territoriality of snowy owls (Nyctea scandiaca) was investigated near Calgary, Alberta, in the winters of 1976–1977 and 1977–1978. Males appeared to be nomadic, although some individuals remained in small areas for periods of up to 17 days. Many females defended territories of 150–450 ha for periods of up to 80 days. Territories of females contained some habitats in excess of their proportion on the study area. This represents selection of habitats with high prey availability. Owls spent more time in such habitats than in resource-poor habitats within their territories. Territory size was inversely related to the proportion of stubble field and the amount of "edge" habitat bordering stubble fields, on the territories. These findings are consistent with an earlier hypothesis that the size of feeding territories is regulated to provide the territory holder with a constant level of food. Juvenile females defended larger territories than did adult females, with higher proportions of nonpreferred habitats. We suggest that these differences result from the inexperience of juveniles in selecting and defending optimal winter territories.

scholarly journals Habitat, food, and small mammal community structure in Namaqualand

Koedoe ◽  
2006 ◽  
Vol 49 (1) ◽  
Author(s):  
M. Van Deventer ◽  
J.A.J. Nel
Keyword(s):  
Species Richness ◽  
Food Availability ◽  
Small Mammal ◽  
Plant Cover ◽  
Plant Litter ◽  
Shrub Cover ◽  
Habitat Features ◽  
Habitat Differences ◽  
Elephant Shrew ◽  
Density And Biomass

The effect of habitat differences and food availability on small mammal (rodent and elephant shrew) species richness, diversity, density and biomass was investigated in Namaqualand, South Africa. Species richness in the three habitats sampled, namely Upland Succulent Karoo, Dry Riverine Shrub and North-western Mountain Renosterveld was low, with only 2–4 species per habitat. Rodents trapped were predominantly Gerbillurus paeba and Aethomys namaquensis, with fewer Mus minutoides and Petromyscus sp. The only non-rodent was the elephant shrew Elephantulus edwardii. Ten habitat features, the percentage of total plant cover, tree cover, shrub cover, grass cover, plant litter, total basal cover, sand, gravel or rock cover, and the dominant plant height were recorded at 30 randomly chosen points on five sampling grids in each habitat. Small mammal density and biomass was significantly correlated with food availability (green foliage cover, seeds, and relative density and biomass of insects). Species richness and diversity of small mammals were significantly correlated with shrub cover. Numbers and biomass of specific species correlated significantly with different habitat features in each case.

scholarly journals Habitat selection when killing primary versus alternative prey species supports prey specialization in an apex predator

2020 ◽  
Author(s):  
B Cristescu ◽  
S Bose ◽  
LM Elbroch ◽  
ML Allen ◽  
Heiko Wittmer
Keyword(s):  
Habitat Selection ◽  
Prey Species ◽  
Puma Concolor ◽  
Apparent Competition ◽  
Selection Function ◽  
Alternative Prey ◽  
Odocoileus Hemionus Columbianus ◽  
Ecological Processes ◽  
Habitat Features ◽  
Selection Of

© 2019 The Zoological Society of London Many predators specialize on one or several prey species that they select from the range of potential prey. Predator specialization on primary versus alternative prey is driven in part by encounter rates with prey and a predator’s habitat selection. Although habitat selection changes with behavioural state, this has not been well-recognized in the resource selection function (RSF) literature to date, often because auxiliary data on the predator’s behavioural states (e.g. hunting) are absent. We monitored habitat selection of pumas Puma concolor in a multi-prey system in northern California, where pumas specialized on black-tailed deer Odocoileus hemionus columbianus. We employed multiple RSF analyses on different datasets to test the following three hypotheses: (1) Pumas utilize habitats in proportion to their availability; (2) Pumas select specific habitat features when killing black-tailed deer, their primary prey; (3) Pumas do not select distinct habitats from those identified under hypothesis 1 when killing alternative prey. We found that pumas in our study selected for specific habitats and habitat features in general, but that their selection was more pronounced when killing black-tailed deer. In summer, kill sites of deer were associated with rugged terrain, but gentle slopes and northerly aspects. In winter, pumas killed deer at low elevations, on gentle slopes and on northerly and westerly aspects. Overall, evidence suggested that pumas tracked their primary prey across seasonal migrations, which were short in distance but resulted in pronounced changes in elevation. When killing alternative prey, pumas showed little evidence of habitat selection, suggesting they may kill alternative prey opportunistically. Our results hold implications for how data should be partitioned when modelling baseline habitat selection of predators, hunting habitat selection and predation risk for prey species, as well as for how we model ecological processes such as apparent competition.

Pike predation affects breeding success and habitat selection of ducks

2010 ◽  
Vol 56 (3) ◽  
pp. 579-589 ◽  
Author(s):  
LISA DESSBORN ◽  
JOHAN ELMBERG ◽  
GÖRAN ENGLUND
Keyword(s):  
Habitat Selection ◽  
Breeding Success ◽  
Selection Of

Effects of agriculture upon populations of native passerine birds of an Alberta fescue grassland

1973 ◽  
Vol 51 (7) ◽  
pp. 697-713 ◽  
Author(s):  
R. A. Owens ◽  
M. T. Myres
Keyword(s):  
Passerine Birds ◽  
Passerculus Sandwichensis ◽  
Disturbed Areas ◽  
Native Grassland ◽  
Savannah Sparrow ◽  
Anthus Spragueii ◽  
Agricultural Use ◽  
Horned Lark ◽  
Sprague's Pipit ◽  
Avian Populations

The effects of several forms of agricultural use of native fescue (Festuca scabrella) grasslands upon populations of native passerine birds were studied in the Hand Hills of southern Alberta in 1970.Censuses of avian populations were carried out on twelve 40-acre (16.2 ha) study plots as well as on two 10-mi (16.1 km) long roadside routes. The vegetation on the study plots and along the roadside routes was described.Native fescue grasslands, undisturbed for 3 years, supported a passerine community consisting of Baird's sparrow (Ammodramus bairdii), Sprague's pipit (Anthus spragueii), savannah sparrow (Passerculus sandwichensis), clay-colored sparrow (Spizella pallida), and western meadowlark (Sturnella neglecta). Incomplete disturbance of fescue grasslands, by mowing for hay or grazing by cattle, reduced or eliminated Baird's sparrow and Sprague's pipit but permitted the ingress of horned lark (Eremophila alpestris) and chestnut-collared longspur (Calcarius ornatus). Total elimination of the native grassland, by ploughing and cultivation for cereal crops, eliminated all passerine species except the horned lark. Peripheral disturbed areas resulting from cultivation, such as held boundaries and roadside ditches, may have benefited several species that tend to occur in ecotonal habitats: savannah sparrow, clay-colored sparrow, and vesper sparrow (Pooecetes gramineus).

Pounce site characteristics of the Western Yellow Robin Eopsaltria griseogularis: the importance of assessing foraging microhabitat

2004 ◽  
Vol 10 (1) ◽  
pp. 21 ◽  
Author(s):  
Jarrad a. Cousin
Keyword(s):  
Leaf Litter ◽  
Substrate Composition ◽  
Habitat Features ◽  
Invertebrate Prey ◽  
Conservation Implications ◽  
Site Characteristics ◽  
Australian Birds ◽  
Close Proximity ◽  
Selection Of

The ground ecosystem represents an important foraging substrate for a large number of Australian birds, including the ground-pouncing Western Yellow Robin Eopsaltria griseogulari. The present study examined the foraging locations of E. griseogularis at the "extreme" microhabitat scale, by measuring ground substrate composition in a 300 mm by 300 mm area surrounding pounce sites, as well as habitat features surrounding pounce sites. Ground substrate composition of pounce sites remained relatively unchanged between seasons, and was characterized by a higher mean percentage of leaf litter and logs when compared to random points. The importance of logs was further emphasized by the closer proximity of logs to pounce sites than to random points. Selection of pounce sites in close proximity to logs and with abundant leaf litter reflects the higher abundance of invertebrate prey associated with these microhabitat attributes, although it may also represent a pounce in close proximity to a log utilized as a perch. During the warmer months of autumn, logs and their associated accumulations of leaf litter, provide sufficient moisture to maintain invertebrate prey, a resource diminished in the surrounding desiccated leaf litter. The conservation implications of these findings are discussed, as is the importance of examining foraging microhabitat in ground-foraging birds.

scholarly journals Breeding Success in the Western Gull × Glaucous-Winged Gull Complex: The Influence of Habitat and Nest-Site Characteristics

The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 353-365 ◽  
Author(s):  
Thomas P. Good
Keyword(s):  
Breeding Success ◽  
Nearest Neighbor ◽  
Physical Structure ◽  
Breeding Performance ◽  
Nesting Ecology ◽  
Larus Occidentalis ◽  
Western Gull ◽  
Hybrid Complex ◽  
Predator Exclusion ◽  
Para Determinar

AbstractThe nesting ecology of breeding pairs of the Western Gull × Glaucous-winged Gull (Larus occidentalis × glaucescens) hybrid complex was investigated at two locations in coastal Washington. In Grays Harbor, breeding performance (clutch size, hatching and fledging success) was highest in vegetated habitat where nests were most dense and where natural screens blocked the nearest neighbor. Egg loss, presumably from gull predators, was common except in areas of dense vegetation. At Tatoosh Island, egg loss was rare, and breeding performance was similar in vegetated and rock habitats. To test if physical structure around open-area nests influenced egg loss in Grays Harbor, predator-exclusion fences were erected around nests on a sandbar island lacking vegetation. Excluding predators reduced egg loss and increased hatching success relative to nests with adjacent natural screens (driftwood logs >30 cm tall) or nests lacking natural screens. Pairs that nest in habitats with adequate habitat structure appear to benefit in terms of lower egg loss and higher nesting success, especially in Grays Harbor. Increasing structure around individual nests may increase breeding success of gulls or other seabirds that experience extensive nest predation.Éxito Reproductivo en el Complejo Larus occidentalis × glaucescens: Influencia del Hábitat y las Características del Sitio de AnidaciónResumen. La ecología de anidación de parejas reproductivas del complejo híbrido Larus occidentalis × glaucescens fue investigada en dos localidades en la costa de Washington. En Grays Harbor, el desempeño reproductivo (en términos del tamaño de la nidada y el éxito de eclosión y emplumamiento) fue máximo en ambientes con vegetación donde los nidos estaban a mayor densidad y donde el vecino más cercano estaba separado por barreras naturales. La pérdida de huevos (presumiblemente ante gaviotas depredadoras) fue común excepto en áreas con vegetación densa. En la isla Tatoosh, la pérdida de huevos fue poco frecuente y el desempeño reproductivo fue similar en ambientes con vegetación y ambientes rocosos. Para determinar si la estructura física alrededor de los nidos en áreas abiertas influenciaba la pérdida de huevos en Grays Harbor, se construyeron cercas para excluir a los depredadores alrededor de nidos en una isla arenosa carente de vegetación. La exclusión de depredadores redujo la pérdida de huevos e incrementó el éxito de eclosión con relación a nidos con barreras naturales adyacentes (troncos de >30 cm de alto) y a nidos sin barreras naturales. Las parejas que anidan en ambientes con estructura de hábitat adecuada parecen beneficiarse en términos de una menor pérdida de huevos y un mayor éxito de anidación, especialmente en Grays Harbor. Incrementar la estructura alrededor de nidos individuales podría aumentar el éxito reproductivo de gaviotas u otras aves marinas sujetas a altos niveles de depredación de nidos.

Nestling foods of the savannah sparrow

1984 ◽  
Vol 62 (1) ◽  
pp. 23-27 ◽  
Author(s):  
Marie Meunier ◽  
Jean Bédard
Keyword(s):  
Breeding Season ◽  
Temporal Changes ◽  
Prey Abundance ◽  
Large Prey ◽  
Passerculus Sandwichensis ◽  
Main Prey ◽  
Savannah Sparrow ◽  
Close Relationship ◽  
Males And Females ◽  
Prey Items

The diet of savannah sparrow (Passerculus sandwichensis) nestlings was monitored at Îsle Verte, Québec, during the 1980 breeding season. Adults carried exclusively arthropods to the nest. The main prey types found were Lepidoptera and Hymenoptera larvae, larval and adult Diptera and Homoptera. The proportion of different prey types in the diet varied during the season but there was no close relationship between temporal changes in the indices of prey abundance in the habitat and the type of prey chosen by the adult birds. Both the type and size of prey brought to the nest changed with the age and number of nestlings (aged 4–10 days). The proportion of Homoptera in the diet decreased sharply with age while that of Lepidoptera and Diptera increased. Adults feeding broods of four brought a larger proportion of large prey items (Lepidoptera and Hymenoptera larvae) than those feeding broods of a lesser size; to these they brought a larger proportion of smaller items such as Diptera and adult Lepidoptera. Males and females brought the same major prey types to the nest but not in the same proportions.

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