6 Potential actions in response to climate change: Terns (Laridae)

In this section we list and assess possible local conservation actions that could be carried out in response to identified climate change impacts on terns . This section is not grouped by species, but by identified impacts. If an impact or action is specific to one or a few species, this information is included in the action summary or in the footnotes.

6.1 Impact: Reduced prey availability during breeding season

Summary:
Several local actions may assist breeding populations on a small scale, but direct intervention on a large scale is likely to be extremely difficult. General conservation actions to protect fish stocks and local marine areas may be the most effective method. If a population is likely to suffer major losses, even with conservation help, then translocations could be considered

Intervention	Evidence of effectiveness	R	S	T
Artificially incubate or hand-rear chicks to support population	Known to be effective for some seabirds, though labour intensive and usually only appropriate for small populations. No examples of hand-rearing terns are currently available, it is unlikely to be a viable option, but more research is needed to verify this.	2	2	1
Make new colonies more attractive to encourage birds to translocate	Many species of tern have been successfully translocated using a variety of techniques to make new areas more attractive, in particular vocalisations and modification of habitat. While not every attempted translocation has been successful, there are numerous notable successes, including successful translocation of large populations containing thousands of individuals.	4	4	3
Provide supplementary food during the breeding season	Trialled on many seabird species, with mixed success. Few, if any, successful examples for terns, though some supplemental feeding has been attempted on a very local scale. Typically very labour intensive and difficult, especially as many tern species strongly prefer living prey and are unlikely to take dead prey. Unlikely to be effective for many terns, or only plausible for small populations.	2	4	3
Translocate the population to a more suitable breeding area	Known to be beneficial in other seabird groups, but few if any examples in terns. Attempts to move populations have typically used attractants to encourage movement, rather than manual translocation. If the target species has high site fidelity, manual translocation may be appropriate but little is known about methods and effectiveness of tern translocation.	2	4	4

Green = Likely to be beneficial. Red = Unlikely to be beneficial, may have negative impact. Orange = contradicting or uncertain evidence. Grey = Limited evidence.
R = relevance rating. S = strength rating. T = transparency rating. All ratings on a scale of 1 to 5, where 5 is the highest.

Detail:

Artificially incubate or hand-rear chicks to support population
Relevance (R): 0 studies in the evidence base focus on terns, 40 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 40 studies. Of these 9 were considered to have a good sample size, and 19 had a clear metric for effectiveness. Transparency (T): 26 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 17 had a published methodology, and 4 justified their rationale.

Make new colonies more attractive to encourage birds to translocate
Relevance (R): 22 studies in the evidence base focus on terns, 16 on other seabirds and 6 on other birds. Strength (S): The evidence base was comprised of 44 studies. Of these 31 were considered to have a good sample size, and 18 had a clear metric for effectiveness. Transparency (T): 44 studies included were published and peer-reviewed, of which 1 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 30 had a published methodology, and 22 justified their rationale.

Provide supplementary food during the breeding season
Relevance (R): 0 studies in the evidence base focus on terns, 16 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 16 studies. Of these 10 were considered to have a good sample size, and 14 had a clear metric for effectiveness. Transparency (T): 16 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 13 had a published methodology, and 4 justified their rationale.

Translocate the population to a more suitable breeding area
Relevance (R): 0 studies in the evidence base focus on terns, 15 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 15 studies. Of these 13 were considered to have a good sample size, and 9 had a clear metric for effectiveness. Transparency (T): 14 studies included were published and peer-reviewed, of which 1 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 11 had a published methodology, and 9 justified their rationale.

6.2 Impact: Increased frequency/severity of storms (including wind, rain and wave action) causes nest destruction

Summary:
While there are several local actions that may prevent or mitigate local nest destruction, they have not been trialled widely and wide-spread evidence to support their use is currently lacking. If changes in extreme weather threatens the viability of a population, then several actions are available to encourage translocation of populations to safer areas.

Intervention	Evidence of effectiveness	R	S	T
Alter habitat to encourage birds to leave an area	There are limited trials of this action, however there are a few successful examples of modifying habitat to encourage terns to leave, typically by encouraging vegetation to overgrow nesting areas. There are currently no available examples in other seabirds.	5	2	3
Artificially incubate or hand-rear chicks to support population	Known to be effective for some seabirds, though labour intensive and usually only appropriate for small populations. No examples of hand-rearing terns are currently available, it is unlikely to be a viable option, but more research is needed to verify this.	2	2	1
Install barriers to prevent flooding	This is a hypothetical action. There are no published studies assessing this action’s effectiveness	NA	NA	NA
Make new colonies more attractive to encourage birds to translocate	Many species of tern have been successfully translocated using a variety of techniques to make new areas more attractive, in particular vocalisations and modification of habitat. While not every attempted translocation has been successful, there are numerous notable successes, including successful translocation of large populations containing thousands of individuals.	4	4	3
Manually relocate nests	There is no published evidence regarding this action’s effectiveness. However, first-hand accounts from practitioners have reported that manually moving nests has been trialled, and with some success. Likely to only be viable for a few nests at the edge of colonies, as larger interventions are laborious, cause mass disturbance, and may result in terns abandoning nests.	NA	NA	NA
Provide additional shelter or protection from extreme weather (flooding)	There have been some attempts to provide shelter for tern populations to protect nests from flooding, however none so far have shown any significant benefit. Novel methods may provide more protection, but this requires further research.	2	3	5
Provide artificial nesting sites	Tried extensively on many seabird species with significant benefit to many species. Artificial nesting sites have been successfully used to support a variety of tern species, including the use of artificial islands, floating rafts and nest-boxes.	3	5	3
Repair/support nests to support breeding	There is limited evidence to support this action, as few trials have been carried out on any seabird species, and those that exist are on a very local scale. No attempts have been made on terns. More research needed to determine effectiveness of this action.	2	2	3
Translocate the population to a more suitable breeding area	Known to be beneficial in other seabird groups, but few if any examples in terns. Attempts to move populations have typically used attractants to encourage movement, rather than manual translocation. If the target species has high site fidelity, manual translocation may be appropriate but little is known about methods and effectiveness of tern translocation.	2	4	4

Detail:

Alter habitat to encourage birds to leave an area
Relevance (R): 2 studies in the evidence base focus on terns, 0 on other seabirds and 0 on other birds. Strength (S): The evidence base was comprised of 2 studies. Of these 2 were considered to have a good sample size, and 0 had a clear metric for effectiveness. Transparency (T): 2 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 2 had a published methodology, and 1 justified their rationale.

Provide additional shelter or protection from extreme weather (flooding)
Relevance (R): 1 study in the evidence base focus on terns, 0 on other seabirds and 2 on other birds. Strength (S): The evidence base was comprised of 3 studies. Of these 1 was considered to have a good sample size, and 2 had a clear metric for effectiveness. Transparency (T): 3 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 3 had a published methodology, and 3 justified their rationale.

Provide artificial nesting sites
Relevance (R): 17 studies in the evidence base focus on terns, 35 on other seabirds and 1 on other birds. Strength (S): The evidence base was comprised of 54 studies. Of these 50 were considered to have a good sample size, and 33 had a clear metric for effectiveness. Transparency (T): 53 studies included were published and peer-reviewed, of which 2 were literature reviews or meta-analyses, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 33 had a published methodology, and 27 justified their rationale.

Repair/support nests to support breeding
Relevance (R): 1 study in the evidence base focus on terns, 1 on other seabirds and 1 on other birds. Strength (S): The evidence base was comprised of 3 studies. Of these 1 was considered to have a good sample size, and 1 had a clear metric for effectiveness. Transparency (T): 3 studies included were published and peer-reviewed, 0 were from the grey literature, and 0 were anecdotal. Of the studies included, 1 had a published methodology, and 3 justified their rationale.