Seed passage trials
As part of my research I am also carrying out seed passage trials; basically to discover how long seeds of different plant species are held within a kererū’s gut. This information will help me estimate how long kererū can carry seeds for and this, combined with data on their movements, can provide insight into how far seeds can be moved.
From previous work, by Debra Wotton, Mick Clout and Dave Kelly on the passage times of several native plant species, larger seeds were found to have longer passage times*. Larger-seeded species, such as tawa (Beilschmiedia tawa), taraire (B. tarairi), and pūriri (Vitex lucens) were found to have average passage times that ranged from 109 minutes to 181 minutes, whereas the smaller seeded species fivefinger (Pseudopanax arboreus) and kahikatea (Dacrycarpus dacrydioides) had shorter average passage times of 37 to 45 minutes*.
This study will aim to expand on this previous work by trialling additional native plant species and by looking at several introduced ones, such as loquat (Eriobotrya japonica) and brush cherry (Syzygium australe). Do the passage times of introduced species follow the same patterns as native plant species?
The trials involve offering captive kererū (birds currently in rehabilitation) fruits of the plant species in question, waiting until they eat them and then waiting until the seeds are defecated and recording the time taken. The defecated seeds are then used in germination trials; more information on those to come later. Sounds simple enough, although it is proving harder than expected to get the birds to eat the offered fruit…turns out they can be quite fussy! So progress has been slower than anticipated, but we are getting there, watch this space for the results!
Many thanks to the Wild Bird Care Charitable Trust for providing us with the opportunity to carry out the seed passage trials at their centre. Check out their webpage (http://birdcare.org.nz/) to find out more about the Trust and what they are up to.
* Wotton, D.M., Clout, M.N. & Kelly, D. 2008. Seed retention times in the New Zealand pigeon (Hemiphaga novaeseelandiae novaeseelandiae). New Zealand Journal of Ecology 32(1): 1-6
From previous work, by Debra Wotton, Mick Clout and Dave Kelly on the passage times of several native plant species, larger seeds were found to have longer passage times*. Larger-seeded species, such as tawa (Beilschmiedia tawa), taraire (B. tarairi), and pūriri (Vitex lucens) were found to have average passage times that ranged from 109 minutes to 181 minutes, whereas the smaller seeded species fivefinger (Pseudopanax arboreus) and kahikatea (Dacrycarpus dacrydioides) had shorter average passage times of 37 to 45 minutes*.
This study will aim to expand on this previous work by trialling additional native plant species and by looking at several introduced ones, such as loquat (Eriobotrya japonica) and brush cherry (Syzygium australe). Do the passage times of introduced species follow the same patterns as native plant species?
The trials involve offering captive kererū (birds currently in rehabilitation) fruits of the plant species in question, waiting until they eat them and then waiting until the seeds are defecated and recording the time taken. The defecated seeds are then used in germination trials; more information on those to come later. Sounds simple enough, although it is proving harder than expected to get the birds to eat the offered fruit…turns out they can be quite fussy! So progress has been slower than anticipated, but we are getting there, watch this space for the results!
Many thanks to the Wild Bird Care Charitable Trust for providing us with the opportunity to carry out the seed passage trials at their centre. Check out their webpage (http://birdcare.org.nz/) to find out more about the Trust and what they are up to.
* Wotton, D.M., Clout, M.N. & Kelly, D. 2008. Seed retention times in the New Zealand pigeon (Hemiphaga novaeseelandiae novaeseelandiae). New Zealand Journal of Ecology 32(1): 1-6