virginianus (Northern Bobwhite) populations showed signs of decline beginning in the early 1900s and are part of a growing list of wildlife species dependent on early successional habitat whose populations are suffering similar fates. Among the numerous factors that contributed to these range-wide declines, most significant are habitat loss and fragmentation due to changes in land use and land cover. In an effort to document landscape composition and cover-type changes, we mapped and analyzed landscape features along 7 breeding bird survey routes on Maryland's Eastern Shore in 2 different years spaced 55 years apart, 1964 and 2019. We calculated total patch area and conducted a randomization test for paired study design to test for differences in land cover after 55 years between the 5 landscape attributes that influence populations dependent on early successional vegetation within an agriculture-dominated landscape. The 5 landscape attributes were agriculture, forest cover, hedgerow length, early successional habitat, and development. In the 55-year span, agricultural land declined from 58.4% to 48.8% and had the largest change in cover area across the 5 landscape attributes. Developed land increased from 7.5% to 12.2%, while forested land remained the same at 24.4%.

Lack of experience in young adult birds may exacerbate the costs of parental care. Thus, birds may modify their behavior over time to balance the costs and benefits of parental care. We observed a population of Spizella pusilla (Field Sparrow) with individuals of known age and identity over multiple years to examine how age of parents affected feeding rates and overall nesting success. Parents fed larger and older broods at higher rates. Feeding rates of paired individuals were also correlated with one another. However, males provisioned offspring at a consistently faster rate than females. Ordinal date and year were the only factors that influenced nest success, with nests failing more frequently early in the summer. These findings may indicate that environmental factors—and less so intrinsic factors—may dictate overall nest success. Although we were unable to detect an effect of parent age on feeding rates, our ability to detect such trends is likely limited by considerable behavioral variation in the population and relatively few birds that were monitored across consecutive years.

The incidence of extra-pair paternity (EPP) is highly variable across bird taxa. While EPP is known to affect reproductive variance, the causes of temporal variation in rates of EPP are poorly studied. Breeding density has often been proposed as an important factor influencing EPP variation, but it has received mixed support. Over a 5-year period we examined the rate of EPP in a socially monogamous Grasshopper Sparrow (Ammodramus savannarum) population on a restored grassland in Maryland. Of 124 broods, 62.1% had extra-pair young (EPY), and of 448 nestlings, 36.8% were the result of extra-pair fertilizations. Over the 5-year study, percent EPY ranged from 26% to 60%. EPP rates were positively correlated with the local density of territorial males, supporting the density hypothesis, and 81% of the EPY were from neighboring males. Male within-pair mating success was related to extra-pair mating, suggesting an active behavioral tradeoff between within-and extra-pair matings, especially at high densities. By examining males at the individual level, we found males that were not cuckolded also had the most genetic offspring (within-pair and extra-pair), whereas males that were cuckolded also failed to sire many extra-pair offspring. Here we show that density plays an important role in the availability of mates, EPP, and the opportunity for sexual selection.

The post-fledging period is a critical life stage for young grassland birds. Habitat selection by recently fledged birds may differ from that of adults and may change as juveniles transition from the care and protection of parents to independence. To describe patterns of habitat selection during these important life stages, we studied habitat use by juvenile Grasshopper Sparrows (Ammodramus savannarum) in a Conservation Reserve Program grassland in Maryland. We used radio-telemetry to track daily movement patterns of two age classes of Grasshopper Sparrows during the post-fledging period. Sparrows were classified as either dependent (<32-d-old) or independent (32-d-old). We characterized the vegetation at 780 vegetation plots (390 plots where birds were located and 390 paired random plots). Microhabitats where dependent birds were found had significantly more bare ground, litter, and plant species richness than paired random plots. In addition, dependent birds were found in plots with less bare ground, more warm-season grass cover, more total vegetation cover, and more forb cover than plots used by independent birds. Plots where independent birds were located also had significantly more bare ground than random plots. Dependent birds are less able to escape from predators because their flight feathers are not fully grown so they may benefit from remaining in areas of greater vegetation cover. However, juveniles transitioning from dependence to independence must forage on their own, possibly explaining their increased use of more open areas where foraging may be easier. To properly manage habitat for grassland birds, management strategies must consider the changing needs of birds during different stages of development. Our results highlight the importance of diverse grassland ecosystems for juvenile grassland birds during the transition to independence.RESUMEN El uso del habitat y patrones de movimiento por dependientes e independientes Ammodramus savannarum floridanus jovenes en el periodo despues de dejar el nido El periodo despues de dejar el nido es una etapa critica de la vida de las aves jovenes de pastizal. Seleccion de habitat por aves que recien dejaron el nido pueden diferir en el uso del habitat de los adultos y puede cambiar a medida cuando los jovenes pierden la atencion y proteccion de los padres en la transicion a la independencia. Para describir los patrones del seleccion de habitat durante las etapas importantes de la vida, se estudio el uso del habitat por Ammodramus savannarum floridanus jovenes en un pastizal Conservation Reserve Program en Maryland, EEUU. Se utilizo la radio telemetria para rastrear los patrones de movimiento diario de dos clases de edad de A. savannarum floridanus durante el periodo despues de dejar el nido. Gorriones fueron clasificados como dependientes (< 32 dias de vida) o independientes ( 32 dias de edad). Hemos caracterizado la vegetacion en 780 parcelas de vegetacion (390 parcelas donde se encontraban las aves y 390 emparejados parcelas al azar). Los micro habitats, donde se encontraron las aves dependientes, tenian significativamente mas suelo desnudo, hojarasca, y un mayor riqueza de especies de plantas en comparacion con las parcelas al azar pareados. Ademas, las aves dependientes fueron encontrados en las parcelas con menos suelo desnudo, mas cobertura de pasto de temporadas calientes, mas cobertura de vegetal, y mas cobertura de hierbas en comparacion con las parcelas utilizadas por las aves independientes. Las parcelas donde se encontraron las aves independientes tambien tenian el suelo significativamente mas desnudo que las parcelas al azar. Aves dependientes tienen menos capacidad de escapar de los depredadores porque sus plumas de vuelo no se han desarrollado completamente, entonces los aves dependientes se puedan beneficiarse de quedar en las zonas de mayor cobertura vegetal. Sin embargo, los jovenes en transicion de la dependencia a la independencia deben alimentarse de manera independiente, lo cual quiza explique el incremento del uso de las zonas mas abiertas donde el forrajeo puede ser mas facil. Para gestionar adecuadamente el habitat para las aves de pastizal, las estrategias de gestion deben tener en cuenta las cambiantes necesidades de las aves durante las diferentes etapas de desarrollo. Nuestros resultados resaltan la importancia de los diversos ecosistemas de pastizales para las aves jovenes de pastizal durante la transicion a la independencia.

Little is known about the post-fledging period in most bird species, and almost nothing has been reported for the family Emberizidae, including New World sparrows. We report here, for the first time, the sizes (wing length and body weight) of, and the distances traveled by fledgling Grasshopper Sparrows within their hatch summer in a restored Atlantic Coastal grassland in Maryland. In the years 2002-2009, we recaptured 24.3% of the 799 banded nestlings in the grasslands at least once within their hatch year. Body weight was not correlated with wing length, wing length did not change with time of recapture, and the average fledgling gained weight by 14% in 100 days. Smaller than average birds were missing from late summer recaptures. As expected, the distance traveled increased significantly with time, but the average fledgling was recaptured 346 m from its nest. The average time of recapture was 33 days after fledging; the youngest recapture was 5 days after fledging and it dispersed a net 580 m from its nest; the longest and fastest distance recorded was 1,615 m from the natal nest in no more than 20 days; the longest recorded retention was 97 days by a local that moved a net distance of 753 m. We conclude that most fledglings in this population of Grasshopper Sparrows remain within their natal habitat for most of the months prior to their pre-formative molt, and that at least 1:4 of them survive at remarkably high rates.

Spiza americana (Dickcissel) colonized a restored Conservation Reserve Program grassland in Maryland during the second year of restoration and has continued to return in subsequent years. In 2000-2010, we banded 125 adult and hatch-year birds; during this period the population ranged annually from one to 16 individuals. Twenty-one percent of adult male Dickcissels (n = 38) returned in a subsequent nesting season, 30% of adult females (n = 20) returned, and 1.7% (n = 67) of the banded hatch-year individuals returned. A female Dickcissel returned to these grasslands after being banded as a nestling the previous year; this bird is the first nestling Dickcissel ever to be re-sighted in a subsequent year across this species range. This same female Dickcissel nested an average of 196.5 m (range = 84-297 m) from her natal site over four breeding seasons, and now holds the longevity record (4 yrs, 11 months) for the species; she also became the first known female Dickcissel to return to a breeding site in Maryland. At our study site, whether adult Dickcissels returned the following summer was not related to their nesting experience (success or failure) the previous year. However, males that were unsuccessful in procuring mates often did not return the following year, and females returned at a greater rate than males.

We studied the breeding biology of Grasshopper Sparrows (Ammodramus savannarum) on restored grasslands in Maryland from 1999 to present. We report the first documented cases of social polygyny in this species. Polygyny increased reproductive success for males in two of four cases, but its rarity suggests it is only a facultative behavior for this usually socially monogamous species Received 31 January 2009. Accepted 3 June 2009.