Geology topics

Chandler S. Robbins

Publications and source records attributed to Chandler S. Robbins.

At least 19 recordsLinked to original sources

USGS2016

Temporal bird community dynamics are strongly affected by landscape fragmentation in a Central American tropical forest region

Habitat loss and fragmentation are considered the main causes of species extinctions, particularly in tropical ecosystems. The objective of this work was to evaluate the temporal dynamics of tropical bird communities in landscapes with different levels of fragmentation in eastern Guatemala. We evaluated five bird community dynamic parameters for forest specialists and generalists: (1) species extinction, (2) species turnover, (3) number of colonizing species, (4) relative species richness, and (5) a homogeneity index. For each of 24 landscapes, community dynamic parameters were estimated from bird point count data, for the 1998–1999 and 2008–2009 periods, accounting for species’ detection probability. Forest specialists had higher extinction rates and a smaller number of colonizing species in landscapes with higher fragmentation, thus having lower species richness in both time periods. Alternatively, forest generalists elicited a completely different pattern, showing a curvilinear association to forest fragmentation for most parameters. Thus, greater community dynamism for forest generalists was shown in landscapes with intermediate levels of fragmentation. Our study supports general theory regarding the expected negative effects of habitat loss and fragmentation on the temporal dynamics of biotic communities, particularly for forest specialists, providing strong evidence from understudied tropical bird communities.

Biodiversity and Conservation↗

USGS2010

Landscape-level impact of tropical forest loss and fragmentation on bird occurrence in eastern Guatemala

Tropical forest destruction and fragmentation of habitat patches may reduce population persistence at the landscape level. Given the complex nature of simultaneously evaluating the effects of these factors on biotic populations, statistical presence/absence modelling has become an important tool in conservation biology. This study uses logistic regression to evaluate the independent effects of tropical forest cover and fragmentation on bird occurrence in eastern Guatemala. Logistic regression models were constructed for 10 species with varying response to habitat alteration. Predictive variables quantified forest cover, fragmentation and their interaction at three different radii (200, 500 and 1000 m scales) of 112 points where presence of target species was determined. Most species elicited a response to the 1000 m scale, which was greater than most species’ reported territory size. Thus, their presence at the landscape scale is probably regulated by extra-territorial phenomena, such as dispersal. Although proportion of forest cover was the most important predictor of species’ presence, there was strong evidence of area-independent and -dependent fragmentation effects on species presence, results that contrast with other studies from northernmost latitudes. Species’ habitat breadth was positively correlated with AIC model values, indicating a better fit for species more restricted to tropical forest. Species with a narrower habitat breadth also elicited stronger negative responses to forest loss. Habitat breadth is thus a simple measure that can be directly related to species’ vulnerability to landscape modification. Model predictive accuracy was acceptable for 4 of 10 species, which were in turn those with narrower habitat breadths.

Cerro San Gil Watershed Protection Reserve↗

USGS2008

Atlantic Flyway review: Region IV Piedmont-Coastal Plain, Fall 2007

Region IV welcomed another coastal station in 2007 with a report from Chris Snook at Charleston, South Carolina. The season was hot and dry throughout Region IV except in Florida where precipitation averaged above normal. Banders blamed their poor success on the lack of cold fronts in August, September, and the first half of October and on persistent strong east winds that blew the migrants farther inland. At Bill Baggs State Park in Miami no significant cold fronts were encountered until 25 Oct, and then on 29 Oct they banded over 100 Black-throated Blue Warblers that should have been on their West Indian wintering grounds by that date. Myrtle Warblers continued to be the most commonly banded species in Region IV, although numbers were down considerably from the previous autumn; their age ratios ranged from 25% hatching year (HY) at inland Tallahassee to 100% HY at coastal Chincoteague. Gray Catbird, which made the top ten list at all11 stations, was in second place, with percent of HYbirds ranging from 54% at Laurel to 95% at Chincoteague. Peak migration days ranged from 19 Sep in Laurel to 14 Nov at Kiptopeke, with five stations reporting their peak during 10-15 Oct. Thanks to the dedicated banders and assistants who contributed 61,825 net-hours in autumn 2007 to band 22,424 birds in Region IV. Thanks also to colleagues Deanna Dawson and John R. Sauer for their helpful comments.

North American Bird Bander↗

USGS2008

Atlantic Flyway review: Region IV Piedmont-Coastal Plain, Fall 2007: Robbins Nest, Laurel, MD (390-0765)

After a gap of two years I resumed banding at this suburban fall-line station on the Patuxent River, my 33rd fall banding season on our two-acre wooded lot. I banded three mornings per week, trying to keep the same schedule as the Patuxent powerline station five miles downstream. I used half as many nets as they did and captured only 15% as many birds. Their location in a large undeveloped area combined with their managed shrub habitat probably accounted for most of the difference. The powerline station favored warblers and kinglets; I did better on cardinals and thrushes. I have witnessed a continuing decline in warblers. In 1997 and 1998 I was still getting four species of warblers among my top ten, and then two or three warbler species through 2004; 2007 was my first year with no warblers among my top ten species. My oldest recapture was a 1 0-year-old Gray Catbird (8051-36905) banded as an AHY on 18 Aug 1998.

Maryland↗

USGS2005

Enhancing the scientific value of the Christmas Bird Count

T he C hristmas B ird C ount (CBC), conducted by the National Audubon Society (NAS) since 1900, constitutes the longest-running and geographically most widespread survey of bird life in the Western Hemisphere. Starting with 25 count locations in its first year, the program has grown continuously ever since, with 20–30 locations currently being added annually. Each CBC consists of a tally of all birds detected within a circle 24.1 km (15 miles) in diameter, on a single day within a few weeks around Christmas (current allowable dates are 14 December through 5 January). More than 50,000 observers now take part each year, in close to 2,000 count circles spread across the U.S. and its territories, southern Canada, and, increasingly, Latin America.

The Auk↗

USGS2005

[Book review] Massachusetts breeding bird atlas

A glance at the dust jacket of this handsome volume drives home the conservation message that breeding bird atlases are designed to promote—that bird populations are changing over vast areas and, unless we become aware of changes in status and take remedial action, some species will disappear from our neighborhoods and even our county or state. A case in point involves the closely related Golden-winged Warbler ( Vermivora chrysoptera ) and Blue- winged Warbler ( Vermivora pinus ). The males are shown in the atlas with their breeding distribution maps. When I was an active birder in the Boston suburbs in the 1930s, the Golden-winged Warbler was a common breeder and it was a treat to find a Blue-winged Warbler. The atlas map 40 years later (1974–1979) shows only five confirmed records statewide for the Golden-winged Warbler, compared with 73 for the Blue-winged Warbler, and the Golden-winged Warbler is now listed as endangered by the Massachusetts Division of Fisheries and Wildlife. Nationally, it is a species of management concern.

The Auk↗

USGS2005

Atlantic Flyway review: Region IV, Piedmont-Coastal Plain, Fall 2004

July, August, and September were cool and wet in the Southeast, with multiple hurricanes threatening the banding stations. Banding results ranged from poor in Laurel and Chincoteague to excellent at Chino Farms, Kiptopeke, Jekyll Island, and the Florida stations. There was little agreement on peak migration days, which ranged from 11 Oct to 6 Nov. Likewise, the date for maximum species ranged from 19 Sep to 9 Oct in Maryland and from 11 Sep to 15 Oct in states farther south. Myrtle Warbler numbers are still below normal, and warblers in general seemed scarcer except at Bill Baggs Cape Florida where warbler numbers approached those at Appalachian stations. Jekyll Island had an extraordinary total of 69 Tennessee Warblers in October, possibly pushed off course by the remnants of Hurricane Matthew in the lower Mississippi valley. Vireos are seldom mentioned in Region IV reports, but this year Blue-headed Vireo was a first for Eden Mill and was a highlight at Jug Bay. Chino Farms banded a record eight Warbling Vireos, Kiptopeke banded a Yellow-throated Vireo and the first Warbling Vireo in at least 11 years. Jekyll Island banders had two Philadelphia Vireos. Finally, Michelle Davis's report from Bill Baggs Cape Florida State Park concludes with the mention of three West Indian vagrants.

North American Bird Bander↗

USGS2005

Atlantic Flyway review: Region IV, Piedmont-Coastal Plain, Fall 2004: Robbins Nest, Laurel, MD (390-0765)

The continuing decline in migratory species is depressing. For a 'migration station' to report Northern Cardinal as the species most commonly banded during the autumn months came as a real shock, especially when the cardinal was so far ahead of second-place catbird. I caught twice as many cardinals as all sparrows combined (including juncos), and the total for cardinals came within ten birds of the total for all warblers combined. Warblers comprised only 16.8% of this fall's catch, compared with an average of 21.7% for the previous five years. Hurricanes Bonnie and Frances passed to the east of us and Charles and Ivan to the west, but none was followed by a landfall of migrants. Last year I reported the sharp drop in Tufted Titmice and Carolina Chickadees locally and the small number of returns from prior years. This year, after no overwintering titmice, numbers have returned to nearly normal, but chickadee numbers are still only half normal. I recaptured cardinals from each year back to 1999, but the only other birds more than two years old were a Carolina Wren and two titmice banded in the autumn of 2000.

Maryland↗

USGS2004

A passion for wildlife: The history of the Canadian Wildlife Service

This intimate historical account was contracted in 1996 by Environment Canada to naturalist-writer Burnett, who interviewed more than 120 present and former Canadian Wildlife Service (CWS) employees of the 1947–1997 period. Each of the 10 chapters addresses a major topic, followed by a brief account of the chief activities of a five-year period. For example, chapter 1 is on “The Genesis of the Canadian Wildlife Service,” followed by highlights of the 1947–1952 period: “Setting the Wildlife Agenda.” The other nine chapters cover the history of enforcement; work with birds, mammals, and fish; habitats; education; toxicology; endangered species; and legislation.

The Auk↗

USGS2004

Atlantic Flyway review: Region IV - Fall 2003

We welcome the Eden Mill station in northeastern Maryland to Region IV this year. With three stations reporting their worst year ever, we really need to be refreshed. After a cool and wet July, August was hot and wet in the east. Temperatures in September remained close to normal, but thanks to tropical storms Henri (6-8 Sep) and Isabel (18 Sep), rainfall was excessive in the Chesapeake Bay states. The entire Northeast had cool weather in October, starting with an early freeze on 3 Oct that triggered some good banding days in our region. Precipitation was unusually spotty in October, but plentiful at most of the Region IV stations. November temperatures were consistently well above the norm, starting with a record-breaking 81 ø in Baltimore on the 1 st . Four of the five Maryland stations had their best day on 19 or 20 Oct. One might expect some of the Virginia coastal stations, Chincoteague, Kiptopeke, and Back Bay, to share the same best day, but they did not. Three stations reported an increase in birds per net hour this year, while seven had a decline. Summarizing the changes in rank in Table 2, Gray Catbird was the species with the most (5) increases in rank (in excess of decreases), followed by junco (4) and Myrtle Warbler and Swamp Sparrow (3 each). Yellowthroat had the most decreases (5), followed by redstart (3). Myrtle Warbler (4572) was once again the most commonly banded species in Region IV, followed by White-throated Sparrow (1723), Gray Catbird (1349), and Western Palm Warbler (1090). Michelle Davis' station on Key Biscayne is the envy of the rest of us. Her top eight species were all warblers and there was not a Myrtle among them. Imagine having Parula, Prairie, and Worm-eating warblers fighting for sixth place! Not showing among the top ten, however, are other surprises. Several banders commented on Sawwhet Owls and Bicknell's Thrushes. Deanna Dawson banded a Cerulean Warbler at Patuxent. Danny Bystrak caught 138 Swamp Sparrows at Jug Bay. In addition to two Clay-colored Sparrows and two Gambel's White-crowns, Jim Gruber at Chino Farms had his first Le Conte's Sparrow and a state high of 39 Lincoln's Sparrows. Dick Roberts' new species at Chincoteague included Yellow-throated and Mourning warblers, while Jethro Runco's best birds at Kiptopeke included S edge Wren and Golden-winged Warbler. The Simpsons at Back Bay finally identified a Western Wood-Pewee after many years of trying. Unusual for Michelle Davis' warbler station on Key Biscayne were Tennessee, Chestnut-sided, and Bay-breasted warblers.

North American Bird Bander↗

USGS2004

Atlantic Flyway review: Region IV - Fall 2003: Robbins Nest, Laurel, MD (390-0765)

The most notable finding at this station in 2003 was the sharp decline in recaptures of previously banded birds and most especially a Crash in the chickadee and titmouse populations. In the autumn of 2001, I recaptured 36 birds banded in previous autumns, but I caught only 24 returns in 2002 and 17 in 2003, a 33% drop each year. In 2002, Tufted Titmouse was my fourth most common species (19 caught) and Carolina Chickadee (15)was in seventh place. This year, I had only four titmice and six chickadees, declines of 79% and 60%. Until now, only the migratory species have been of concern. We suspect West Nile virus is responsible. However, the oldest bird we recaptured this year was Blue Jay 723-42798, banded as HY in 1993, a species known to be especially vulnerable to West Nile. Half of this year's returns were cardinals, the oldest of which was only four years of age. My birds/100nh continues to drop each year without any noticeable change in surrounding habitat. The only banded migrant known to have remained here for more than a week was a Swainson's Thrush that weighed 31.9 g on 4 Oct and 41.6 g nine days later, an increase of 30%.

Maryland↗

USGS2002

Atlantic Flyway review: Piedmont-Coastal Plain, Region IV, Fall 2001

The Hollywood, Butler Island, and Wekiva Basin stations did not operate this year, but we welcome back Jekyll Island, GA, with its flagship species, Western Palm Warbler (835); and we are glad to have a report from Rock Springs Run State Reserve in Florida to replace the Wekiva Station. Except for a couple of good rains in August, the second half of the year was droughty in Maryland and Virginia, while Florida had a surplus of rain throughout the autumn. Baltimore recorded its driest fall since 1941. The 2001 stream inflow entering Chesapeake Bay was 36 percent below normal, securing the status of the region's longest running drought since the 1960s. Part of the extended drought can be blamed on two consecutive years without a hurricane making landfall in continental United States--the first time in two decades that this had happened. September and October averaged cooler than normal throughout the region, but the other months had excessive heat. The stations that opened in early August detected little movement in the first half of the .month. States to the north of us were experiencing record-breaking heat, culminating in the hottest day in the past quarter century in New York City (104 ° F) on 9 Aug. On the following day he temperature 40 feet below the surface of Lake Erie more than three miles off Cleveland reached 80 ° F for the first time in history.

North American Bird Bander↗

USGS2002

Atlantic Flyway review: Piedmont-Coastal Plain, Region IV, Fall 2001: Robbins Nest, Laurel, MD (390-0765)

I continue to band before and after work and all day on weekends on my two and a half acres along the Patuxent River gorge between highway 1-95 and the Laurel city limits. Our kids have long since flown the coop, so I have no one to run the station when I am out of town; thus, I miss some of the best flight days. The chief changes in habitat over the years have been replacement of pines by young deciduous growth, loss of dogwoods in the mature deciduous forest, and gradual replacement of lawn by shrubbery. To explore changes in fall migration patterns, I compared my banding totals for the first five years of systematic fall banding with those of the most recent five years. By coincidence the totals were nearly identical: 2175 birds in 1973-1977 and 2169 in 1997-2001. However, my net hour totals were vastly different: 9124 in the first five years compared with 26,284 for the current period. It took nearly 2.9 times the effort to catch the same number of birds I used to band. Next year, my 30 th , I'll be checking to see which species I am losing and which are maintaining their numbers. I had 35 returns of a dozen species, but all were either summer, winter, or permanent residents. The oldest this time was only four years old, a Gray Catbird. Eleven transients repeated on a subsequent day. The one longest in residence was a Gray-cheeked Thrush that l captured 10 times in 17 days; it weighed 31.0 g when banded and reached a maximum of 51.7 g 13 days later.

Maryland↗

USGS2000

Atlantic Flyway review: Piedmont-Coastal Plain, Region IV, Fall 1999

In a slight reorganization, the Mount Nebo station in the mountains of western Maryland near Oakland was moved to Region III (Western Ridge), in exchange for Lakeshore Estates in Leon County, Florida, which we welcome to Region IV. This was the year of the hurricane in Region IV, with the majority of stations commenting on summer drought, persistent easterly winds, or hurricanes. Nine of the ten stations that operated in both 1998 and 1999 banded fewer birds in the 1999 season, the notable exception being Chino Farms, which jumped from 5193 to 8225 birds and also had a 3% increase in birds per 100 net-hours. Summing across these ten stations: 27,911 birds were banded in 1998, 24,753 in 1999, a decrease of 11%. (Net-hours are not available for all sites for 1998). Yellow-rumped Warbler was again the most commonly banded, followed again by Common Yellowthroat (which was among the top ten species at all sites except Lakeshore Estates at Tallahassee), and with the American Goldfinch a surprise in third place.

North American Bird Bander↗

USGS2000

Atlantic Flyway review: Piedmont-Coastal Plain, Region IV, Fall 1999: Robbins Nest, Laurel, MD (390-0765)

This is the first of three stations along the Patuxent River. Elevation here at the edge of the Piedmont ranges from 265 ft at the house to 160 ft at the river. In spite of easterly winds and heavily overcast skies from Hurricanes Dennis, Floyd, and Irene, we suffered from drought all summer, not rain. We had only about two inches each in June and July, 4.55 in August, then a whopping 16.03 in September, and a normal 3.46 in October. This station operates all day on weekends, but only before and after work on other days. Net-hours were 5% above the 26-year mean of 3655, but way down from last year because other commitments kept me out of town on several weekends. I had only 14 days when I could net all day. Although the most birds were banded on opening day, the most per net-hour were on 19 and 15 October and 23 September. The nets caught 26 returns from prior years, the oldest being a seven-year-old Blue Jay and a seven-year-old cardinal. To illustrate how biased a sample one can obtain from netting, I captured only one junco in the nets, but caught 47 of them in baited traps on our deck. Other species taken only in the traps (and not included in the totals) were Mourning Dove, Chipping Sparrow, House Finch, Pine Siskin, and American Goldfinch.

Maryland↗

USGS1998

Atlantic Flyway review: Piedmont-Coastal Plain Region IV - Fall 1997: Robbins Nest, Laurel, MD (390-0765)

The 25th year of fall banding at this back yard station atop the Patuxent River gorge between Laurel and the 1-95 bridge netted more birds of summer and winter resident species than migrants. Myrtle Warbler was the only one of the six commonest species captured that is primarily a transient here. My 5214 net-hours, my fourth highest, were 48% above the 24-year mean of 3512, but the only species to exceed their previous high were Carolina Chickadee and Magnolia Warbler. Part of the reason for my low catch per 100 net-hours in recent years is the dieoff of dogwood from anthracnose and destruction of the shrub layer in my mature woods by an overpopulation of deer. For the first time, deer destroyed three of my nets. We also had the driest summer in decades, which killed some of the shallow-rooted vegetation this year. The greatest declines from last year were in catbird (51 to 32), Hermit Thrush ( 27 to 12 ), and Blackand-white Warbler (11 to 3), and the greatest increases were in Myrtle Warbler (2 to 34), Carolina Chickadee (6 to 36), and Tufted Titmouse (10 to 31). The biggest changes from the mean of the first five years (1973-77) to the most recent five years (1993-97), not corrected for the 147% increase in net-hours, are increases in Rubythroated Hummingbird (1.2 to 7.6 ), Black-throated Blue Warbler (1.8 to 11.6), Common Yellowthroat (5.0 to 17.6), and House Finch (0.2 to 6.0), and decreases in Swainson's Thrush (26.6 to 17.2), Gray-cheeked/Bicknell's Thrush (9.4 to 3.8), Scarlet Tanager (6.6 to 2.2), and American Goldfinch (3.0 to 0.4). The oldest of my 39 returns were a six-year-old Gray Catbird and a five-year-old Carolina Chickadee. Two birds banded here during the fall migration of 1995 were found to the northeast of here in the summer of 1997: a Ruby-throated Hummingbird (8000-85102) in Philadelphia, PA, and a Hermit Thrush (1521-58503) at Wentworth, NH. A Savannah Sparrow was the 121st species banded on our suburban wooded hectare.

Maryland↗

USGS1996

In memoriam: Harvey I. Fisher, 1916-1994

Harvey Irvin Fisher was born on 15 June 1916 in Edgar, Nebraska, and spent his youth near Blue Springs, Missouri. Following his A.A. from Kansas City in 1935, and B.S. from Kansas State University in 1937, he married Mildred Hoch; they had three sons. He received his Ph.D. from the University of California, Berkeley, in 1942. From 1942 through 1945, while at Berkeley, he was Technical Curator, Museum of Vertebrate Zoology, Biologist with the Crocker Radiation Laboratory, and Assistant Editor of The Condor . In 1944 he joined the AOU, became a Fellow in 1950, and was Editor of The Auk from 1948 to 1952 (to which he contributed numerous book reviews). He later became a Fellow of the American Association for the Advancement of Science and of the International Academy of Science.

The Auk↗

USGS1996

In memoriam: Robert Earl Stewart, Sr., 1913-1993

Robert Earl Stewart, Sr., our colleague, close friend, and mentor, was born on 16 April 1913 in Kansas City, Missouri. He graduated from high school in Grimes, Iowa, received his B.S. in Biology from the University of Iowa in 1936, and his M.S. in Zoology from the University of Michigan in 1937. His post-graduate work on the life history of the Common Yellow throat was published in the Wilson Bulletin in 1953. Bob joined the AOU in 1938, was made an Elective Member in 1949, and a Fellow in 1974. During World War II, he served with the U.S. Navy Medical Corps in the Pacific Theater.

The Auk↗