Observation of Parental Behavior One plot was label for attendance recording. In this area, eleven pairs of parents were successfully caught and marked, along with their nests. One unpaired parent was also caught and labeled, but the partner was never tagged. For the 11 marked nests, at least one 48 hour continuous watch will be conducted to determine the duration of foraging trips and the number of times parents deliver food. Pairs of parents were banded and stained with picric acid. One parent was picric stained at the top of the breast and the other at the bottom. A record will be kept of each bird returning to the nest with a food load, leaving the nest with an empty gular pouch, and every time it is spotted leaving and arriving the colony. Along with the double labeled water energetic trials and corticosterone levels, these combined data will provide an indication of how hard parents are working to provide food for their chick. The teams at the different colonies are excited about using both the data from the time-depth-recorders and observations of forage trip durations to compare the feeding behavior of birds foraging in the contrasting areas.
Bird Observation Map
A sketch of a map showing bird locations.
Corticosterone Sampling: Blood sampling of Little Auks will give a lot of information. Corticosterone is a stress hormone produced in many animals. It is circulated in the blood and is delivered to the brain. It’s quantity in a body indicates the level of stress an animal is under. Levels of corticosterone, in some seabird species, have been shown to reflect food availability and body condition. So this hormone may be a sensitive indicator of the biological response to variation or change in local food abundance. Blood samples were collected several times during this breeding season to quantify levels of corticosterone in breeding Little Auks. The technique is as follows: random breeding birds are caught on noose carpets and as soon they begin to struggle, a stop watch is started. The adult is gathered, and held firmly, the brachial vein on the wing is found, and blood samples, < 100 micro liters, are collected within three minutes. After the nick has stopped bleeding, all other body measurements are taken and the bird is released back into its nest. Samples are taken at each stage from a random sampling of 30 birds from throughout the colony. Samples are taken in the following sequence; first during mid incubation, then later incubation, early chick rearing, mid chick rearing, and finally late chick rearing.
Sample sizes are large enough to compare seasonal levels of corticosterone between males and females. Female parents leave the colony at the end of chick rearing, leaving the males to escort the fledgling to sea. This behavior may be related to female body reserves being depleted after egg laying.
Comparisons between incubation, chick rearing, and fledging periods will be made among years at Kap Hoegh and between this colony and those at Spitsbergen. Levels of corticosterone measured throughout the season here and at each of the study sites will help understand the relationship between the physiological condition of breeding Little Auks and local food availability.
Vocabulary: Physiological condition
**Productivity Studies: How well do the chicks grow? ** This research hopes to answer this question. The goal of the productivity studies is to learn about the reproductive success of parents. There are two aspects of this; hatching success (number of chicks hatched compared with the number of eggs laid) and fledging success (number of fledglings compared with number of hatched chicks). Regular nest checks also allow the team to determine the time of hatch and fledge. Past research has shown that both of these parameters may indicate local foraging conditions.
Using a flashlight, possible nest crevices are peeked into. The majority of nests are too deep to observe or on unstable slopes so, several days were just dedicated to finding accessible nests. This is far less than one percent of total nests present. Any nest with eggs or birds incubating eggs are recorded along with the date. Sometimes Little auks are just heard within the nest. The nests are mapped and reexamined every other day for evidence of chick hatch. All eggs that successfully become chicks will be continuously monitored. At birth the chicks are unable to thermo-regulate (maintain their internal body temperature) so must be brooded continuously by a parent. Beginning at about five days after birth, when the chicks are old enough to be left unattended, basic morphometrics (mass, wing length, culmen, tarsus, headbill) are measured and recorded every other day until fledging. Seven or eight data points (days worth of data) are needed. Since the chicks fledge at 21-28 days, the collection attempts must be frequent.
On July 24, my narrower arms were used to reach into nesting crevices at three nests to gather the chick. For two of the nests a little black fluffball was recovered. In the last one, the chick skillfully hunkered down into an unreachable corner. That one would need to be tried again on the 25th. A typical growth curve of a Little Auk chick has a linear section between about five and fifteen days of age. Chicks then reach a peak mass (the heaviest the chick will get at about nineteen days old) and then lose mass prior to fledging. The age at fledging and mass at fledging are also sought after. Each of these gives information on the health of the chick, and therefore, the quality and quantity of food supply being delivered.
**Little Auks Growth Chart
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Survival Re-sighting: Do Little auks come back?
One research plot is designed to find out.
This is the third and final field season for the East Greenland portion of the Little Auk study. Little Auks have been banded in the 2005 and 2006 seasons, within one 10 X 10 meter plot. Survival re-sighting is done during two, three-day sessions with continuous observations recorded for a seven hour period, looking for birds banded in prior years. Two of the Spitsbergen sites are also collecting this information. With this data, overwinter survival can be determined at the different sites.