Is mass loss in Brünnich’s guillemots Uria lomvia an adaptation for improved flight performance or improved dive performance?

نویسندگان

  • Kyle H. Elliott
  • Shoshanah R. Jacobs
  • Julian Ringrose
  • Anthony J. Gaston
  • Gail K. Davoren
  • K. H. Elliott
چکیده

Breeding Brünnich’s guillemots Uria lomvia show stepwise mass loss at the time of hatch. This mass loss has usually been explained as an adaptation to reduce the cost of flight during the chick-rearing period because flight time increases during that period. It is possible, however, that mass loss also increases dive performance during the chick-rearing period because time spent diving also increases during that period. Reduced mass could reduce basal metabolic rate or costs associated with buoyancy and therefore increase aerobic dive limit. To examine the role of mass loss in dive behavior, we attached time-depth-temperature recorders for 24 48 h to chick-rearing and incubating Brünnich’s guillemots at Coats Island, Nunavut (2005: n 45, 2006: n 40), and recorded body mass before and after each deployment. There was no relationship between mass and dive duration during either incubation or chick-rearing. Seventeen of the birds we sampled during incubation were resampled during chick-rearing. For this group, dive duration increased with mass loss between incubation and chick-rearing (r 0.67 0.75). Mass loss occurred through reductions in metabolically-active tissues (liver, bladder) and buoyant tissues (lipids) although muscle and gut mass did not change. Despite the large change in lipids, buoyancy only changed by 0.1%, and mass loss therefore did not have much effect on costs associated with buoyancy. Nonetheless, surface pause duration for a given dive depth decreased during chick-rearing, supporting the idea that reduced mass led to increased aerobic dive limit through reduced metabolic rate and inertial costs; oxygen stores did not increase. We also attached neutrally (n 9) and negatively (n 11) buoyant handicaps to the legs of adults to assess the effect of artificial mass increases on time budgets. Artificially increasing mass decreased total time spent diving but did not change time spent flying. There was no change in shift length between incubation and chick-rearing, and therefore no support for the idea that mass loss reflected a change in fasting endurance requirements. An energetic model suggested that the observed mass reduction reduced dive costs by 5 8% and flight costs by 3%. We concluded that mass loss may be as important for increasing dive performance as increasing flight performance.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Body mass changes in Brünnich’s guillemots Uria lomvia with age and breeding stage

Body mass of Brünnich’s guillemots Uria lomvia breeding at Coats Island, Canada, was measured during incubation and chick-rearing in 1988 /2001. In most years, mass increased during incubation and fell after hatching, leveling off by the time chicks were 18 d old, close to the age at which chicks departed. Mass during incubation increased with age up to about 12 yr, but the mass of birds broodi...

متن کامل

Adult Brünnich’s Guillemots Uria lomvia balance body condition and investment in chick growth

To investigate the covariation of adult body condition and nestling growth, we weighed adult Brünnich’s Guillemots Uria lomvia rearing chicks at Coats Island, Nunavut, Canada, each year between 1988 and 2002. We estimated chick mass at 14 days for a sample of chicks reared in the same years. Adult mass and chick mass at 14 days were highly correlated, suggesting that, as feeding conditions dete...

متن کامل

Weakening of the subpolar gyre as a key driver of North Atlantic seabird demography: a case study with Brünnich’s guillemots in Svalbard

The Arctic is experiencing environmental changes at unprecedented rates. These changes are spreading throughout the entire food web, affecting apex predators such as seabirds. Brünnich’s guillemot Uria lomvia populations in Svalbard archipelago have significantly declined since the mid-1990s. For longlived species such as seabirds, population growth rate is highly sensitive to changes in adult ...

متن کامل

Individual specialization in diet by a generalist marine predator reflects specialization in foraging behaviour.

1. We studied chick diet in a known-age, sexed population of a long-lived seabird, the Brünnich's guillemot (Uria lomvia), over 15 years (N = 136; 1993-2007) and attached time-depth-temperature recorders to examine foraging behaviour in multiple years (N = 36; 2004-07). 2. Adults showed specialization in prey fed to offspring, described by multiple indices calculated over 15 years: 27% of diet ...

متن کامل

Swim speeds and stroke patterns in wing-propelled divers: a comparison among alcids and a penguin.

In diving birds, the volume and resulting buoyancy of air spaces changes with dive depth, and hydrodynamic drag varies with swim speed. These factors are important in the dive patterns and locomotion of alcids that use their wings both for aerial flight and underwater swimming and of penguins that use their wings only for swimming. Using small data-loggers on free-ranging birds diving to 20-30 ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2008