Reproduction

Reproduction is a major step in all organisms life cycles whether it is a zygotic, gametic, or alternation of generation life cycle. The little blue penguin goes through a gametic lifecycle were the major portion of its’ lifecycle is in a multicellular diploid stage.

Gametic lifecycle tree. Created by Dr. Tony Sanderfoot from the University of Wisconsin-La Crosse.

In the little blue penguin’s lifecycle, the gametes multiply by meiosis inside an individual adult. There are two types of gametes, eggs which are made in a female adult and sperm which are made in the male adult. In the little blue penguins case the sperm are motile and the egg is immotile. The sperm are released from the male penguin and travel in the female’s vagina to the ovaries where the egg is produced. One sperm will fertilize the egg and a little blue penguin’s life begins. The monogamous little blue penguin reproduces sexually and fertilizes on average 1 to 2 eggs (Nisbet and Dann 2009).  In an 18 year study from 1986-2004, the average clutch for the little blue penguins on Phillip Island was 1.94 (Nisbet and Dann 2009).

The little blue penguin is a unique seabird and goes through its’ life cycle stage of reproduction on land (Nisbet and Dann 2009, Saraux et al 2011, Ancel et al 2013). The geographical region where most of the little blue penguins reside is Australia, New Zealand and the surrounding islands (Saraux et al 2011).

Map of where little blue penguins are found to breed. The picture was created by Dr. Richard Roscoe.

On land the little blue penguin will create a burrow which acts as a shelter and a place to undergo reproduction (Braidwood et al 2011). The burrow that the penguin produces is usually underground in soft soil, but can be in rock crevices, under trees, caves (Waas 1990, Braidwood et al 2010), under driftwood (Heber et al. 2008, Braidwood et al. 2010), and even in urban areas (Giling et al. 2008). The little blue penguins find many different places to live due to the fact that they need to be close to the sea for foraging purposes (Williams 1995, Braidwood et al. 2010).

 

Once the little blue penguin establishes a nesting site they are most likely to return to the same site year after year (Roscoe 2013, Nisbet and Dann 2009). One reason that a little blue penguin would not return to the same nesting site from the previous year could be due to an unsuccessful breeding attempt (Johannesen et al. 2002, Braidwood et al. 2010).  Dr. Richard Roscoe states on his little blue penguin website that the little blue penguin reproduces around September in the New Zealand region. If the conditions are right and food is plentiful the penguins have been observed lying eggs from May to February. The time of the year when reproduction takes place is different in every nesting site. This is due to the fact of local climatic effects, such as abundance of food, playing a huge role in determining when a little blue penguin will reproduce. During the other remaining months of the year, the bird is out foraging in the sea to prepare itself to breed (Roscoe 2013).  The penguins prefer to breed and live in colonies that can range from ten pairs to a thousand pairs of birds (Waas 1990). The size of the colony can play a huge role in the success of an individual or also be a negative factor as well. Smaller populations can suffer from reduced amount of genetic diversity, and be more susceptible to environmental changes (Couvet 2002, Braidwood et al. 2010).  Larger populations may be safe from land predators due to the fact of numbers, but also make it easier for harmful diseases to spread due to close quarter living.

Baby blue penguin from a colony at Harris Bay, Banks Peninsula New Zealand. Photo was taken by Steve Attwood

A little blue penguin is mature to start breeding around the age of 2 or 3 (Nisbet and Dann 2009). As the penguin gets more experience with breeding, which comes with age, the more successful the pair will be with offspring survival (Nisbet and Dann 2009).  As the blue penguin reaches the age of about 8, the productivity of breeding starts to decrease till the bird’s death (Nisbet and Dann 2009).  Some other variables that could affect the productivity of a little blue penguin could be a change of mate, laying dates, and change of burrow (Nisbet and Dann 2009). All these variables play a huge role in the success of the little blue penguin population as a whole and raises questions to why the population is declining in areas of Australia and New Zealand (Braidwood et al. 2010, Dann et al. 2000). See Interactions for some reasons for the decline in the penguin population. Once the bird is at maturity the male penguin will start its journey to find a mate. Courtship begins when the male creates displays or acoustic calls for other females to see or hear (Chung 2011).  One of the displays the male penguin can do is get in an upright position with its flipper behind its back and outstretch its neck to sky and let out a loud braying sound to attract a possible mate (Chung 2011).  If a female is attracted to the male, the two birds will perform a “dance” together (Chung 2011).  Through observation, males and females tend to return to the same nesting site year after year (Roscoe 2013). There is a divorce rate amongst mates and could be due to an unsuccessful breeding attempt (Roscoe 2013, Williams 1995).

Little blue penguin eggs from a colony at Harris Bay, Banks Peninsula New Zealand. Photo was taken by Steve Attwood Baby little blue penguins from a colony at Harris Bay, Banks Peninsula New Zealand. Photo was taken by Steve Attwood

Once the egg(s) are laid the parents will take turns incubating the egg(s) while the other parent goes out to the sea to forage (Saraux et al. 2011). Depending on food density, foraging trips can last for a single day to weeks during the incubation stage (Roscoe 2013).  When the egg(s) are laid they are smooth and white in color and weigh on average 53 grams and have an average diameter of 53 mm (Chung 2011). The incubating period usually takes 30 to 40 days (Chung 2011 and Roscoe 2013). If the pair has two eggs both eggs usually hatch 1 to 3 days from each other (Roscoe 2013). Once the chicks have hatched, they are very vulnerable to the elements and rely on their parents for food, protection, and warmth (Chung 2011, Roscoe 2013, Saraux et al. 2011).  A little blue penguin usually weighs around 35 grams out of the egg and grows to 1 kilogram (Nisbet and Dann 2009, Chung 2011). The next three weeks the parents will again take turns guarding their young while the other goes out to get food to bring back to the chicks (Chung 2011, Roscoe 2013, Saraux et al. 2011).  Fledglings reach their independence when their parents teach them how to forage out at sea (Roscoe 2013). This process usually takes place 8 to 10 weeks after the birth of the fledglings, and the juveniles usually will not return to their parents’ burrow (Chung 2011 and Roscoe 2013).

Check out some of the interactions that the little blue penguin engages in everyday!

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