Geology topics

J.E. Jonsson

Publications and source records attributed to J.E. Jonsson.

5 recordsLinked to original sources

USGS2009

Genetic differentiation between sympatric and allopatric wintering populations of Snow Geese

Blackwater National Wildlife Refuge on the Delmarva Peninsula, Maryland, USA has been the wintering area of a small population of Lesser Snow Geese (Chen caerulescens caerulescens; LSGO) since the 1930s. Snow Geese primarily pair in wintering areas and gene flow could be restricted between this and other LSGO wintering populations. Winter pair formation also could facilitate interbreeding with sympatric but morphologically differentiated Greater Snow Geese (C. c. atlantica; GSGO).We sequenced 658 bp of the mitochondrial DNA control region for 68 Snow Geese from East Coast and Louisiana wintering populations to examine the level of genetic differentiation among populations and subspecies. We found no evidence for genetic differentiation between LSGO populations but, consistent with morphological differences, LSGO and GSGO were significantly differentiated. We also found a lack of genetic differentiation between different LSGO morphotypes from Louisiana. We examined available banding data and found the breeding range of Delmarva LSGO overlaps extensively with LSGO that winter in Louisiana, and documented movements between wintering populations. Our results suggest the Delmarva population of LSGO is not a unique population unit apart from Mid-Continent Snow Geese. ?? 2009 by the Wilson Ornithological Society.

Wilson Journal of Ornithology↗

USGS2007

Does body size influence nest attendance? A comparison of Ross's geese (Chen rossii) and the larger, sympatric lesser snow geese (C. caerulescens caerulescens)

The body-size hypothesis predicts that nest attendance is positively related to body size among waterfowl and that recess duration is inversely related to body size. Several physiological and behavioral characteristics of Ross's geese (Chen rossii) suggest that females of this species should maintain high nest attendance despite their relatively small body size. Accordingly, we used 8-mm films to compare the incubation behavior of Ross's geese to that of the larger, closely-related lesser snow geese (C. caerulescens caerulescens; hereafter, snow geese) nesting sympatrically at Karrak lake, Nunavut, Canada in 1993. We found that nest attendance averaged 99% for both species. Our results offer no support for the body-size hypothesis. We suggest that temperature requirements of embryos in relation to short incubation duration and a low foraging efficiency of females select for high nest attendance in both snow geese and Ross's geese. ?? Dt. Ornithologen-Gesellschaft e.V. 2007.

Journal of Ornithology↗

USGS2006

Do geese fully develop brood patches? A histological analysis of lesser snow geese (Chen caerulescens caerulescens) and Ross's geese (C. rossii)

Most birds develop brood patches before incubation; epidermis and dermis in the brood patch region thicken, and the dermal connective tissue becomes increasingly vascularized and infiltrated by leukocytes. However, current dogma states that waterfowl incubate without modifications of skin within the brood patch region. The incubation periods of lesser snow geese (Chen caerulescens caerulescens; hereafter called snow geese) and Ross's geese (C. rossii) are 2-6 days shorter than those of other goose species; only females incubate. Thus, we hypothesized that such short incubation periods would require fully developed brood patches for sufficient heat transfer from incubating parents to eggs. We tested this hypothesis by analyzing the skin histology of abdominal regions of snow and Ross's geese collected at Karrak Lake, Nunavut, Canada. For female snow geese, we found that epidermis and dermis had thickened and vascularization of dermis was 14 times greater, on average, than that observed in males (n=5 pairs). Our results for Ross's geese (n=5 pairs) were more variable, wherein only one of five female Ross's geese fully developed a brood patch. Our results are consistent with three hypotheses about brood patch development and its relationship with different energetic cost-benefit relationships, resulting from differences in embryonic development and body size. ?? Springer-Verlag 2006.

Journal of Comparative Physiology B: Biochemical, ↗

USGS2006

Ecological and physiological factors affecting brood patch area and prolactin levels in arctic-nesting geese

We investigated effects of ecological and physiological factors on brood patch area and prolactin levels in free-ranging Lesser Snow Geese ( Chen caerulescens caerulescens ; hereafter “Snow Geese”) and Ross's Geese ( C. rossii ). On the basis of the body-size hypothesis, we predicted that the relationships between prolactin levels, brood patch area, and body condition would be stronger in Ross's Geese than in the larger Snow Geese. We found that brood patch area was positively related to clutch volume and inversely related to prolactin levels in Ross's Geese, but not in Snow Geese. Nest size, nest habitat, and first egg date did not affect brood patch area in either species. Prolactin levels increased as incubation progressed in female Snow Geese, but this relationship was not significant in Ross's Geese. Prolactin levels and body condition (as indexed by size-adjusted body mass) were inversely related in Ross's Geese, but not in Snow Geese. Our findings are consistent with the prediction that relationships between prolactin levels, brood patch area, and body condition are relatively stronger in Ross's Geese, because they mobilize endogenous reserves at faster rates than Snow Geese.

The Auk↗

USGS2006

Different time and energy budgets of Lesser Snow Geese in rice-prairies and coastal marshes in southwest Louisiana

Many bird species use human-made habitats and an important issue is whether these are equally suitable foraging habitats as are historical, natural habitats. Historically, Lesser Snow Geese (Chen caerulescens caerulescens, hereafter Snow Geese) wintered in coastal marshes in Louisiana but began using rice-prairies within the last 60 years. Time spent feeding was used as an indicator of habitat suitability and time and energy budgets of Snow Geese were compared between rice-prairies and coastal marshes in southwest Louisiana. Composite diets of Snow Geese have a lower energy density in the rice-prairies than in coastal marshes; thus, we predicted that Snow Geese would spend relatively more time feeding in rice-praires to obtain existence energy. However, time spent feeding was higher in coastal marshes and thus, not proportional to energy density of composite diets. Snow Geese in coastal marshes ingested less apparent metabolizable energy than did Snow Geese in rice-prairies. In rice-prairies, juveniles spent more time feeding than did adults; however, time spent feeding was similar between age classes in coastal marshes. Undeveloped foraging skills probably cause juvenile Snow Geese to forage less efficiently in coastal marshes than in rice-prairies. These findings are consistent with recent trends in Snow Goose numbers, which increased in rice-prairies but remained stable in coastal marshes.

Waterbirds↗