Parasite Prevalence in Dark-eyed Juncos, &lt;em&gt;Junco hyemalis&lt;/em&gt;, Breeding at Different Elevations

Bears, Heather

doi:10.22621/cfn.v118i2.919

Cited by 5 publications

(7 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One scenario is that the high workload during reproduction compromises resistance to parasites and reduces survival (Stjernman, Raberg & Nilsson 2004). In support of this idea, we found lower incidences of blood parasites in high‐ compared to low‐elevation adults and fledglings in this system (Bears 2004). Another scenario is that, if low‐elevation birds shunt energy into reproduction for an extended period, adults and fledglings may end up at a lower nutritional state by the end of the season, decreasing their chances of over‐winter survival (Badyaev 1997; Badyaev & Ghalambor 2001).…”

Section: Discussionsupporting

confidence: 63%

“…There is some evidence for trade‐offs between reproduction and survival and/or offspring quality with elevation; birds at higher elevations that have lower seasonal production may survive longer (Sandercock et al . 2005a,b), produce higher quality offspring (Badyaev & Ghalambor 2001; Bears 2002), or have fewer parasitic infections (Stabler, Kitzmiller & Braun 1974; Bears 2004). In order to evaluate shifts in overall life‐history strategies as opposed to elevation‐specific variation in vital rates, there is a need to study multiple traits in a single, controlled system, enabling one to observe inter‐related traits that co‐vary with elevation.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Breeding in high‐elevation habitat results in shift to slower life‐history strategy within a single species

Bears

Martin

White

2009

Journal of Animal Ecology

128

148

View full text Add to dashboard Cite

Summary 1.Elevational gradients create environmental variation that is hypothesized to promote variation in life-history strategies. We tested whether differences in life-history strategies were associated with elevation in a songbird, the dark-eyed junco ( Junco hyemalis; Aves; A.O.U. 1998). 2. We monitored birds in four replicated sites per elevation, at 2000 m a.s.l. (high elevation) and 1000 m a.s.l. (low elevation), in the Rocky Mountains of Canada. 3. Over 5 years, we measured the following traits and vital rates: egg-laying schedules, morphological indicators of reproductive stage, seasonal reproductive success, indicators of competitive class (age, size, arrival time), and survival rates. 4. We found two main patterns: with an increase in breeding elevation, dark-eyed juncos delayed the development of structures necessary for reproduction (e.g. cloacal protuberance in males) and reduced the duration of their reproductive period to less than half of the time used by low-elevation birds; and 5. Juncos at high-elevation sites had 55-61% lower annual reproductive success and 15 to 20% higher survival rates. While adult juncos at high elevations produced fewer offspring, those offspring were in better condition. Proportions of age and size classes in high-compared to low-elevation populations were similar, suggesting that a life-history trade-off is present, rather than competition forcing inferior competitors to breed in a peripheral habitat. The apparent trade-off between reproduction and survival corresponded to a shorter period of favourable weather and available food in high-compared to low-elevation habitats. 6. Thus, elevation had a strong influence on life-history characteristics of a single species over a short spatial distance, suggesting a shift in life history from a high reproductive strategy at lower elevations to a high survivor strategy at high elevations. 7. This is the first paper to show a shift in avian life-history strategies along an elevational gradient (in both genders, of multiple age classes) when region (latitude) and phylogenetic histories are controlled for.

show abstract

Section: Discussionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Breeding in high‐elevation habitat results in shift to slower life‐history strategy within a single species

Bears

Martin

White

2009

Journal of Animal Ecology

128

148

View full text Add to dashboard Cite

show abstract

“…Longer beaks have also been shown to benefit birds in preening to kill ectoparasites, which are common in young birds (Clayton et al 2005). If external parasites are higher in low‐elevation birds, similar to patterns seen in blood parasites (Bears 2004), there may be strong selective pressure for longer maxillary overhangs on the culmens of young birds. Maxillary overhangs are prone to breakage and wear over time, which may explain why beak lengths in older ASY age groups no longer differed between elevations (Clayton et al .…”

Section: Discussionmentioning

confidence: 96%

“…Pearson cross-correlation coefficients of eight morphological traits of wild-caught and captive dark-eyed juncos (Junco hyemalis) from Jasper National Park,Alberta, Canada, 2000, 2004. N 0298.…”

mentioning

confidence: 99%

“…habitats in the Canadian Rocky Mountains. The dark‐eyed junco is an emberizid commonly used in studies of morphological and life‐history variation along environmental gradients (Miles and Ricklefs 1984, Nolan and Ketterson 1990, Chandler and Mulvihill 1990, Bears 2002, 2004, Bears et al 2003). Jasper National Park was chosen as a study site because the habitat is unfragmented and juncos breed continuously along the elevational range, and therefore allopatric genetic differention due to habitat fragmentation preventing gene flow is unlikely.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Comparative morphology of dark-eyed juncosJunco hyemalisbreeding at two elevations: a common aviary experiment

Bears

Drever²,

Martin³

2008

Journal of Avian Biology

Self Cite

View full text Add to dashboard Cite

Morphologies of bird species often vary along elevation gradients, yet causes of the variation have not been examined experimentally. We investigated variation in morphological traits of the dark-eyed junco Junco hyemalis, breeding at 1,000 m a.s.l. (low-elevation; i.e. low) and 2,000 m asl (high-elevation; i.e. high) in the Rocky Mountains, Canada. Eight morphological traits were measured in free-living birds. We found two consistent differences in populations between elevations: at high-elevation sites, females had longer wings and males had longer tails than birds from low-elevation sites. Other age-and gender-specific results were observed in free-living birds between elevations: tarsi were shorter in high-elevation second year (SY) females and after second year (ASY) males, beak lengths were slightly longer in lowelevation SY females, and high-elevation ASY females tended to have lower fat than low-elevation ASY females. Morphological differences may result from genetic differences between elevations, or phenotypic flexibility resulting from exposure to the different environmental conditions. To identify which mechanism caused the difference in morphometrics, hand-reared birds from low-and high-elevation habitats were raised in identical conditions with unlimited access to high quality food until they had replaced all feathers. The traits measured in the lab (wing and rectrix length, weight and fat score) tended to increase in magnitude compared to field values. Juncos from high-and lowelevations had similar responses to the aviary environment, with one exception: males from high-elevation sites had greater weight gain relative to free-living juncos than males from low-elevation sites. Thus, morphological traits in darkeyed juncos were phenotypically flexible, capable of growing larger in the laboratory environment. However, there were also persistent genetic or perinatal/maternal differences underlying population responses that prevented traits from converging under aviary conditions. As a result, trait size differences between high-and low-elevation populations were maintained or exacerbated in the common aviary environment.

show abstract

Physiological impacts of chronic and experimental Plasmodium infection on breeding-condition male songbirds

Talbott

Ketterson

2023

Sci Rep

View full text Add to dashboard Cite

While Plasmodium parasitism is common in songbirds, its impact on avian reproduction is unclear owing to conflicting reports in the existing literature. Particularly understudied is the impact of phase of infection on variation in host reproductive physiology in wild, breeding-condition birds. However, assessing the full impact of Plasmodium on reproductive success in the wild can be difficult because individuals experiencing severe effects of parasitism may not enter the breeding population and may be less likely to be captured during field studies. To address these factors, we quantified metrics of health and reproductive physiology in wild-caught, breeding-condition male dark-eyed juncos (Junco hyemalis hyemalis) before and after experimental Plasmodium inoculation in a captive setting. Metrics of health and reproductive physiology included activity rate, hematocrit, scaled body mass, testosterone and sperm production. Individuals already infected at capture (i.e., chronically infected) had higher levels of hematocrit than males without chronic infections. Experimentally infected males showed a larger reduction in hematocrit and activity rate as compared to controls. However, chronic infection status did not influence the extent of metric decline. Testosterone production did not vary by treatment and most birds produced sperm following inoculation. Broadly, our results suggest that male juncos exposed to Plasmodium during the breeding season likely experience declines in general health, but Plasmodium infections do not negatively impact reproductive physiology. We conclude that physiological tradeoffs in males may favor maintenance of reproductive function despite infection.

show abstract

Parasite Prevalence in Dark-eyed Juncos, <em>Junco hyemalis</em>, Breeding at Different Elevations

Cited by 5 publications

References 17 publications

Breeding in high‐elevation habitat results in shift to slower life‐history strategy within a single species

Breeding in high‐elevation habitat results in shift to slower life‐history strategy within a single species

Comparative morphology of dark-eyed juncosJunco hyemalisbreeding at two elevations: a common aviary experiment

Physiological impacts of chronic and experimental Plasmodium infection on breeding-condition male songbirds

Contact Info

Product

Resources

About