Listen and Read 67 - Ecology

 Thẩm Tâm Vy, Oct. 31st, 2020 LISTEN AND READ 67 
LISTEN AND RAD 67 
Ecology 
Rats, palms and Palmyra Island 
The law of unintended consequences manifests itself on a Pacific atoll 
 IN THE HIERARCHY of conservationists’concerns, animals often seem to trump 
plants. For example, feral rats that live on islands after having been introduced 
accidentally by passing ships are excoriated because of the damage they do to local 
wildlife. More than 100 island-based animals have been exterminated or are imperilled 
by these rodents—birds being at particular risk through loss of eggs and nestlings. The 
effects of the interlopers on the local flora are, however, less well investigated. 
 Rats’ main source of nutrition being 
seeds and fruit, this is a surprising 
omission. But it has been rectified in 
part by a project undertaken by Ana 
Miller-ter Kuile of the University of 
California, Santa Barbara. The object 
of Ms Miller-ter Kuile’s attention was 
Palmyra, an atoll that is one of the 
most remote specks of land in the 
Pacific Ocean. And, as she describes in 
Biotropica, by focusing on the atoll’s 
plants she showed just how extensive 
an effect rats can have on an isolated 
island’s ecology. She also showed, 
though, that restoring matters to the 
status quo ante bellum is not as easy 
as might be hoped. 
 Palmyra, an American territory, is the 
northernmost of the Line Islands. At 
the moment it has no permanent human 
residents. But it does host a scientific 
base that is home, at any given time, to 
a couple of dozen researchers. During 
the Second World War, however, it was the site of a naval airbase—and along with the 
ships, planes and personnel that serviced this base came rats. 
 Because of the damage these rodents cause, the elimination of rats from small islands 
like this one has become something of a cottage industry in recent years. More than 400 
have been thus cleared of their infestations. Palmyra’s turn was scheduled for 2011, and 
Ms Miller-ter Kuile saw this as an opportunity to observe how the local plants would 
respond. 
 In 2007 she and her colleagues established seven vegetation-monitoring plots on the 
atoll, each 300 square metres in area. They observed the plants in these plots until the 
moment, four years later, when doom for Palmyra’s rats rained down from the skies in 
the form of bait stations loaded with poison. That this bombardment did for the rats 
successfully was confirmed the following year, by the setting up of further bait stations. 
Not a single station was touched. The animals were gone. Ms Miller-ter Kuile and her 
colleagues waited a further three years for things to settle down, and then got back to 
the task of monitoring their plots. They did so for four more years. 
 No good deed goes unpunished 
 The difference this second time around was palpable. During both periods of 
examination, the researchers concentrated their efforts on juvenile trees. Between 2007 
and 2011 they found that the mass of such trees remained unchanged. Between 2014 
and 2017 it rose 14-fold. Ironically, however, the main beneficiary of this expansion 
was the coconut palm. 
 Though coconut palms do grow wild on Pacific islands, those on Palmyra are, like the 
rats which once inhabited it, aliens. They are the descendants of palms imported to 
create copra plantations. In the 1850s, before people started taking an interest in the 
place, Palmyra’s coconut-palm population is reckoned to have been about 4,000 adult 
trees. Copra farming changed this and, though the last planation was abandoned many 
years ago, the consequence was that in 2005 the coconut-palm population exceeded 
53,000. Now that the rats are gone, Ms Miller-ter Kuile’s work suggests this population 
will grow yet bigger. 
 Even without its rats, then, Palmyra’s ecosystem looks unlikely to return to anything 
approaching its prelapsarian state without further human assistance. In 2019 the 
Nature Conservancy, an American charity that now owns most of the atoll, began a 
further project: uprooting coconutpalm sprouts to give other species, particularly the 
delightfully named grand devil’s claw, a chance. Whether culling the coconuts in this 
way will also have unintended consequences remains to be seen. 
 [The Economist US, October 31st, 2020] 
 Notes: 
 - to excoriate: làm tuột da; [nghĩa bóng] chỉ trích gay gắt 
 - interlopers: loại cây cỏ, thú vật xâm phạm 
 - atoll: đảo san hô vòng 
 - status quo ante bellum [Latin]: nguyên trạng trước chiến tranh 
 - palpable = clear to be seen; obvious 
 - copra plantations: trang trại trồng dừa 
 - prelapsarian state: tình trạng trước khi bị sa sút, sa ngã