Learn Hardcore Croatian: Moja sestra volontira na Svjetski dan životinja i pomaže u azilu cijeli vikend. - My sister volunteers on World Animal Day and helps in the shelter the whole weekend.

If sestra were, for example, the direct object (“I see my sister”), then you’d say moju sestru (accusative).
Here, since it’s “My sister volunteers… and helps…”, nominative is required, so moja sestra is correct.

Why is the verb volontira used instead of something like je volonter?

Volontira is the verb “to volunteer” (she volunteers), while volonter is the noun “volunteer”.

Moja sestra volontira = “My sister volunteers” (focus on the activity).
Moja sestra je volonter = “My sister is a volunteer” (focus on her role/identity).

In this sentence we’re talking about what she is doing on that specific occasion (she volunteers on World Animal Day), so the verb volontira is more natural.

Why is it na Svjetski dan životinja and not za Svjetski dan životinja or na Svjetskom danu životinja?

Na Svjetski dan životinja (literally “on World Animal Day”) uses:

na
- accusative (Svjetski dan) to express “on (a specific day / occasion)”.
životinja is in the genitive plural (“of animals”) depending on dan (“Day of Animals”).

Compare:

Na Svjetski dan životinja pomaže… = On World Animal Day she helps…
Na Svjetskom danu životinja (locative) would sound like you are focusing on being at an event called “World Animal Day” (a bit more like “at the World Animal Day event”), but in everyday speech na Svjetski dan is the usual pattern for dates/occasions.

Za Svjetski dan životinja would more likely mean “for World Animal Day” in the sense of “in preparation for / in honor of” it, not “on that day”.

Why is Svjetski dan in that form and not Svjetski dani or Svjetskog dana?

Svjetski dan is:

singular (one day, not multiple days)
masculine gender
accusative case (because of na
- accusative to mean “on (that day)”)

Forms:

Nominative: Svjetski dan
Genitive: Svjetskog dana
Accusative: Svjetski dan (same form as nominative for masculine inanimate nouns)

So na Svjetski dan = “on World Day”.
You would use Svjetskog dana in a structure like tijekom Svjetskog dana (“during the World Day”).

Why is životinja in that form? Why not životinje?

Životinja here is genitive plural (of animals) after dan:

dan životinja = “day of animals” (genitive plural)
base form: životinja (sg.), životinje (pl. nominative)
genitive plural of many feminine nouns in -a is identical to the singular form: životinja.

So:

životinje (nominative plural) = animals (as the subject: Životinje su…)
životinja (genitive plural) = of animals (dan životinja – day of animals)

That’s why it’s Svjetski dan životinja.

What’s the difference between pomaže and pomaže se? Why is there no se here?

Pomaže is the simple form of the verb pomagati = “to help”.
Se is not needed here because pomaže is transitive and takes a direct/indirect object:

pomaže u azilu = she helps (out) at the shelter

Pomaže se can appear in other contexts with a reflexive/impersonal meaning (e.g. Tu se pomaže ljudima – “People are helped here”), but for “My sister helps…” you just use pomaže without se.

Why is it u azilu and not u azil?

With the preposition u, Croatian distinguishes:

u
- locative = “in/at” (location, where something is)
u
- accusative = “into” (movement, direction)

Here the meaning is “helps at the shelter”, a location, so we use u + locative:

u azilu (locative) = in/at the shelter
u azil (accusative) = into the shelter (movement: e.g. ulazi u azil – “she enters the shelter”)

Since she is doing volunteer work there, not moving into it, u azilu is correct.

Does azil always mean “animal shelter”? I’ve seen it used for refugees too.

Azil in Croatian can mean:

Asylum (political, refugee context):
- tražiti azil = to seek asylum
Animal shelter, especially in everyday speech:
- azil za životinje = animal shelter

In this sentence, because of Svjetski dan životinja and volunteering context, azil clearly means “animal shelter”. If that weren’t obvious, you could say u azilu za životinje to make it explicit.

Why is cijeli vikend at the end? Could I say cijeli vikend pomaže u azilu?

Word order in Croatian is flexible, and cijeli vikend (“the whole weekend”) can move for emphasis.

All of these are grammatically correct:

…i pomaže u azilu cijeli vikend.
Neutral; focuses first on location, then duration.
…i cijeli vikend pomaže u azilu.
Emphasizes “all weekend” more strongly at the beginning of the clause.
…cijeli vikend pomaže u azilu.
Also possible, context decides what sounds most natural.

The original order is very typical: place (u azilu) then time (cijeli vikend).

Why is it cijeli vikend and not cijelog vikenda?

Both exist, but they have different cases/roles:

cijeli vikend = accusative (duration: “for the whole weekend”)
cijelog vikenda = genitive (often “during the whole weekend / of the whole weekend”)

In expressions of how long something lasts, Croatian usually uses accusative of time:

radim cijeli dan = I work all day
učila je cijelu noć = she studied all night
pomaže u azilu cijeli vikend = she helps at the shelter all weekend

So cijeli vikend is the standard way to express duration here.

Why are the verbs volontira and pomaže both in the present tense if this seems to describe a specific event?

Croatian often uses the present tense for:

Regular/habitual actions:
- Moja sestra volontira… = She (regularly) volunteers…
A known, scheduled near-future event:
- e.g. Sutra volontira na… (“Tomorrow she volunteers at…” – present with future meaning)

From context alone, this sentence can be understood in two ways:

She regularly volunteers on World Animal Day and helps at the shelter all weekend (every year).
She is going to volunteer this year on World Animal Day and help all weekend (implied future, but grammatically present).

Croatian leaves that to context; using present is normal in both readings.

Could I replace cijeli vikend with vikendom? What would change?

Yes, but the meaning changes:

cijeli vikend = the whole weekend (one specific weekend or each time that particular weekend comes)
vikendom = on weekends (generally, every weekend, habitual action)

So:

…pomaže u azilu cijeli vikend.
She helps at the shelter throughout the weekend in question.
…pomaže u azilu vikendom.
She helps at the shelter on weekends (as a general habit, every weekend).

Is it necessary to repeat moja sestra before pomaže or is it clear without repetition?

It is clear without repetition. In Croatian, once the subject is established, you usually don’t repeat it, especially with i (“and”):

Moja sestra volontira… i pomaže…
= My sister volunteers… and (she) helps…

The subject moja sestra is understood for both verbs. Repeating it (Moja sestra volontira… i moja sestra pomaže…) would sound heavy and unnatural unless you had a specific stylistic reason to emphasize the subject again.